diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 1cd5589..5adc128 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -104,6 +104,8 @@
     ssl_ticket.c
     ssl_tls.c
     ssl_tls13_keys.c
+    ssl_tls13_server.c
+    ssl_tls13_client.c
 )
 
 if(CMAKE_COMPILER_IS_GNUCC)
diff --git a/library/Makefile b/library/Makefile
index 0ee6e4f..8c58fb8 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -167,6 +167,8 @@
 	  ssl_ticket.o \
 	  ssl_tls.o \
 	  ssl_tls13_keys.o \
+	  ssl_tls13_client.o \
+	  ssl_tls13_server.o \
 	  # This line is intentionally left blank
 
 .SILENT:
diff --git a/library/aes.c b/library/aes.c
index a15a809..8e3358c 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -57,29 +57,6 @@
 #define AES_VALIDATE( cond )        \
     MBEDTLS_INTERNAL_VALIDATE( cond )
 
-/*
- * 32-bit integer manipulation macros (little endian)
- */
-#ifndef GET_UINT32_LE
-#define GET_UINT32_LE(n,b,i)                            \
-{                                                       \
-    (n) = ( (uint32_t) (b)[(i)    ]       )             \
-        | ( (uint32_t) (b)[(i) + 1] <<  8 )             \
-        | ( (uint32_t) (b)[(i) + 2] << 16 )             \
-        | ( (uint32_t) (b)[(i) + 3] << 24 );            \
-}
-#endif
-
-#ifndef PUT_UINT32_LE
-#define PUT_UINT32_LE(n,b,i)                                    \
-{                                                               \
-    (b)[(i)    ] = (unsigned char) ( ( (n)       ) & 0xFF );    \
-    (b)[(i) + 1] = (unsigned char) ( ( (n) >>  8 ) & 0xFF );    \
-    (b)[(i) + 2] = (unsigned char) ( ( (n) >> 16 ) & 0xFF );    \
-    (b)[(i) + 3] = (unsigned char) ( ( (n) >> 24 ) & 0xFF );    \
-}
-#endif
-
 #if defined(MBEDTLS_PADLOCK_C) &&                      \
     ( defined(MBEDTLS_HAVE_X86) || defined(MBEDTLS_PADLOCK_ALIGN16) )
 static int aes_padlock_ace = -1;
@@ -409,7 +386,7 @@
     {
         pow[i] = x;
         log[x] = i;
-        x = ( x ^ XTIME( x ) ) & 0xFF;
+        x = MBEDTLS_BYTE_0( x ^ XTIME( x ) );
     }
 
     /*
@@ -418,7 +395,7 @@
     for( i = 0, x = 1; i < 10; i++ )
     {
         RCON[i] = (uint32_t) x;
-        x = XTIME( x ) & 0xFF;
+        x = MBEDTLS_BYTE_0( XTIME( x ) );
     }
 
     /*
@@ -431,10 +408,10 @@
     {
         x = pow[255 - log[i]];
 
-        y  = x; y = ( ( y << 1 ) | ( y >> 7 ) ) & 0xFF;
-        x ^= y; y = ( ( y << 1 ) | ( y >> 7 ) ) & 0xFF;
-        x ^= y; y = ( ( y << 1 ) | ( y >> 7 ) ) & 0xFF;
-        x ^= y; y = ( ( y << 1 ) | ( y >> 7 ) ) & 0xFF;
+        y  = x; y = MBEDTLS_BYTE_0( ( y << 1 ) | ( y >> 7 ) );
+        x ^= y; y = MBEDTLS_BYTE_0( ( y << 1 ) | ( y >> 7 ) );
+        x ^= y; y = MBEDTLS_BYTE_0( ( y << 1 ) | ( y >> 7 ) );
+        x ^= y; y = MBEDTLS_BYTE_0( ( y << 1 ) | ( y >> 7 ) );
         x ^= y ^ 0x63;
 
         FSb[i] = (unsigned char) x;
@@ -447,8 +424,8 @@
     for( i = 0; i < 256; i++ )
     {
         x = FSb[i];
-        y = XTIME( x ) & 0xFF;
-        z =  ( y ^ x ) & 0xFF;
+        y = MBEDTLS_BYTE_0( XTIME( x ) );
+        z = MBEDTLS_BYTE_0( y ^ x );
 
         FT0[i] = ( (uint32_t) y       ) ^
                  ( (uint32_t) x <<  8 ) ^
@@ -590,7 +567,7 @@
 
     for( i = 0; i < ( keybits >> 5 ); i++ )
     {
-        GET_UINT32_LE( RK[i], key, i << 2 );
+        RK[i] = MBEDTLS_GET_UINT32_LE( key, i << 2 );
     }
 
     switch( ctx->nr )
@@ -600,10 +577,10 @@
             for( i = 0; i < 10; i++, RK += 4 )
             {
                 RK[4]  = RK[0] ^ RCON[i] ^
-                ( (uint32_t) FSb[ ( RK[3] >>  8 ) & 0xFF ]       ) ^
-                ( (uint32_t) FSb[ ( RK[3] >> 16 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) FSb[ ( RK[3] >> 24 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) FSb[ ( RK[3]       ) & 0xFF ] << 24 );
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_1( RK[3] ) ]       ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_2( RK[3] ) ] <<  8 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_3( RK[3] ) ] << 16 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_0( RK[3] ) ] << 24 );
 
                 RK[5]  = RK[1] ^ RK[4];
                 RK[6]  = RK[2] ^ RK[5];
@@ -616,10 +593,10 @@
             for( i = 0; i < 8; i++, RK += 6 )
             {
                 RK[6]  = RK[0] ^ RCON[i] ^
-                ( (uint32_t) FSb[ ( RK[5] >>  8 ) & 0xFF ]       ) ^
-                ( (uint32_t) FSb[ ( RK[5] >> 16 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) FSb[ ( RK[5] >> 24 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) FSb[ ( RK[5]       ) & 0xFF ] << 24 );
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_1( RK[5] ) ]       ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_2( RK[5] ) ] <<  8 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_3( RK[5] ) ] << 16 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_0( RK[5] ) ] << 24 );
 
                 RK[7]  = RK[1] ^ RK[6];
                 RK[8]  = RK[2] ^ RK[7];
@@ -634,20 +611,20 @@
             for( i = 0; i < 7; i++, RK += 8 )
             {
                 RK[8]  = RK[0] ^ RCON[i] ^
-                ( (uint32_t) FSb[ ( RK[7] >>  8 ) & 0xFF ]       ) ^
-                ( (uint32_t) FSb[ ( RK[7] >> 16 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) FSb[ ( RK[7] >> 24 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) FSb[ ( RK[7]       ) & 0xFF ] << 24 );
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_1( RK[7] ) ]       ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_2( RK[7] ) ] <<  8 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_3( RK[7] ) ] << 16 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_0( RK[7] ) ] << 24 );
 
                 RK[9]  = RK[1] ^ RK[8];
                 RK[10] = RK[2] ^ RK[9];
                 RK[11] = RK[3] ^ RK[10];
 
                 RK[12] = RK[4] ^
-                ( (uint32_t) FSb[ ( RK[11]       ) & 0xFF ]       ) ^
-                ( (uint32_t) FSb[ ( RK[11] >>  8 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) FSb[ ( RK[11] >> 16 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) FSb[ ( RK[11] >> 24 ) & 0xFF ] << 24 );
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_0( RK[11] ) ]       ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_1( RK[11] ) ] <<  8 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_2( RK[11] ) ] << 16 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_3( RK[11] ) ] << 24 );
 
                 RK[13] = RK[5] ^ RK[12];
                 RK[14] = RK[6] ^ RK[13];
@@ -713,10 +690,10 @@
     {
         for( j = 0; j < 4; j++, SK++ )
         {
-            *RK++ = AES_RT0( FSb[ ( *SK       ) & 0xFF ] ) ^
-                    AES_RT1( FSb[ ( *SK >>  8 ) & 0xFF ] ) ^
-                    AES_RT2( FSb[ ( *SK >> 16 ) & 0xFF ] ) ^
-                    AES_RT3( FSb[ ( *SK >> 24 ) & 0xFF ] );
+            *RK++ = AES_RT0( FSb[ MBEDTLS_BYTE_0( *SK ) ] ) ^
+                    AES_RT1( FSb[ MBEDTLS_BYTE_1( *SK ) ] ) ^
+                    AES_RT2( FSb[ MBEDTLS_BYTE_2( *SK ) ] ) ^
+                    AES_RT3( FSb[ MBEDTLS_BYTE_3( *SK ) ] );
         }
     }
 
@@ -809,52 +786,52 @@
 }
 #endif /* MBEDTLS_CIPHER_MODE_XTS */
 
-#define AES_FROUND(X0,X1,X2,X3,Y0,Y1,Y2,Y3)                     \
-    do                                                          \
-    {                                                           \
-        (X0) = *RK++ ^ AES_FT0( ( (Y0)       ) & 0xFF ) ^       \
-                       AES_FT1( ( (Y1) >>  8 ) & 0xFF ) ^       \
-                       AES_FT2( ( (Y2) >> 16 ) & 0xFF ) ^       \
-                       AES_FT3( ( (Y3) >> 24 ) & 0xFF );        \
-                                                                \
-        (X1) = *RK++ ^ AES_FT0( ( (Y1)       ) & 0xFF ) ^       \
-                       AES_FT1( ( (Y2) >>  8 ) & 0xFF ) ^       \
-                       AES_FT2( ( (Y3) >> 16 ) & 0xFF ) ^       \
-                       AES_FT3( ( (Y0) >> 24 ) & 0xFF );        \
-                                                                \
-        (X2) = *RK++ ^ AES_FT0( ( (Y2)       ) & 0xFF ) ^       \
-                       AES_FT1( ( (Y3) >>  8 ) & 0xFF ) ^       \
-                       AES_FT2( ( (Y0) >> 16 ) & 0xFF ) ^       \
-                       AES_FT3( ( (Y1) >> 24 ) & 0xFF );        \
-                                                                \
-        (X3) = *RK++ ^ AES_FT0( ( (Y3)       ) & 0xFF ) ^       \
-                       AES_FT1( ( (Y0) >>  8 ) & 0xFF ) ^       \
-                       AES_FT2( ( (Y1) >> 16 ) & 0xFF ) ^       \
-                       AES_FT3( ( (Y2) >> 24 ) & 0xFF );        \
+#define AES_FROUND(X0,X1,X2,X3,Y0,Y1,Y2,Y3)                 \
+    do                                                      \
+    {                                                       \
+        (X0) = *RK++ ^ AES_FT0( MBEDTLS_BYTE_0( Y0 ) ) ^    \
+                       AES_FT1( MBEDTLS_BYTE_1( Y1 ) ) ^    \
+                       AES_FT2( MBEDTLS_BYTE_2( Y2 ) ) ^    \
+                       AES_FT3( MBEDTLS_BYTE_3( Y3 ) );     \
+                                                            \
+        (X1) = *RK++ ^ AES_FT0( MBEDTLS_BYTE_0( Y1 ) ) ^    \
+                       AES_FT1( MBEDTLS_BYTE_1( Y2 ) ) ^    \
+                       AES_FT2( MBEDTLS_BYTE_2( Y3 ) ) ^    \
+                       AES_FT3( MBEDTLS_BYTE_3( Y0 ) );     \
+                                                            \
+        (X2) = *RK++ ^ AES_FT0( MBEDTLS_BYTE_0( Y2 ) ) ^    \
+                       AES_FT1( MBEDTLS_BYTE_1( Y3 ) ) ^    \
+                       AES_FT2( MBEDTLS_BYTE_2( Y0 ) ) ^    \
+                       AES_FT3( MBEDTLS_BYTE_3( Y1 ) );     \
+                                                            \
+        (X3) = *RK++ ^ AES_FT0( MBEDTLS_BYTE_0( Y3 ) ) ^    \
+                       AES_FT1( MBEDTLS_BYTE_1( Y0 ) ) ^    \
+                       AES_FT2( MBEDTLS_BYTE_2( Y1 ) ) ^    \
+                       AES_FT3( MBEDTLS_BYTE_3( Y2 ) );     \
     } while( 0 )
 
 #define AES_RROUND(X0,X1,X2,X3,Y0,Y1,Y2,Y3)                 \
     do                                                      \
     {                                                       \
-        (X0) = *RK++ ^ AES_RT0( ( (Y0)       ) & 0xFF ) ^   \
-                       AES_RT1( ( (Y3) >>  8 ) & 0xFF ) ^   \
-                       AES_RT2( ( (Y2) >> 16 ) & 0xFF ) ^   \
-                       AES_RT3( ( (Y1) >> 24 ) & 0xFF );    \
+        (X0) = *RK++ ^ AES_RT0( MBEDTLS_BYTE_0( Y0 ) ) ^    \
+                       AES_RT1( MBEDTLS_BYTE_1( Y3 ) ) ^    \
+                       AES_RT2( MBEDTLS_BYTE_2( Y2 ) ) ^    \
+                       AES_RT3( MBEDTLS_BYTE_3( Y1 ) );     \
                                                             \
-        (X1) = *RK++ ^ AES_RT0( ( (Y1)       ) & 0xFF ) ^   \
-                       AES_RT1( ( (Y0) >>  8 ) & 0xFF ) ^   \
-                       AES_RT2( ( (Y3) >> 16 ) & 0xFF ) ^   \
-                       AES_RT3( ( (Y2) >> 24 ) & 0xFF );    \
+        (X1) = *RK++ ^ AES_RT0( MBEDTLS_BYTE_0( Y1 ) ) ^    \
+                       AES_RT1( MBEDTLS_BYTE_1( Y0 ) ) ^    \
+                       AES_RT2( MBEDTLS_BYTE_2( Y3 ) ) ^    \
+                       AES_RT3( MBEDTLS_BYTE_3( Y2 ) );     \
                                                             \
-        (X2) = *RK++ ^ AES_RT0( ( (Y2)       ) & 0xFF ) ^   \
-                       AES_RT1( ( (Y1) >>  8 ) & 0xFF ) ^   \
-                       AES_RT2( ( (Y0) >> 16 ) & 0xFF ) ^   \
-                       AES_RT3( ( (Y3) >> 24 ) & 0xFF );    \
+        (X2) = *RK++ ^ AES_RT0( MBEDTLS_BYTE_0( Y2 ) ) ^    \
+                       AES_RT1( MBEDTLS_BYTE_1( Y1 ) ) ^    \
+                       AES_RT2( MBEDTLS_BYTE_2( Y0 ) ) ^    \
+                       AES_RT3( MBEDTLS_BYTE_3( Y3 ) );     \
                                                             \
-        (X3) = *RK++ ^ AES_RT0( ( (Y3)       ) & 0xFF ) ^   \
-                       AES_RT1( ( (Y2) >>  8 ) & 0xFF ) ^   \
-                       AES_RT2( ( (Y1) >> 16 ) & 0xFF ) ^   \
-                       AES_RT3( ( (Y0) >> 24 ) & 0xFF );    \
+        (X3) = *RK++ ^ AES_RT0( MBEDTLS_BYTE_0( Y3 ) ) ^    \
+                       AES_RT1( MBEDTLS_BYTE_1( Y2 ) ) ^    \
+                       AES_RT2( MBEDTLS_BYTE_2( Y1 ) ) ^    \
+                       AES_RT3( MBEDTLS_BYTE_3( Y0 ) );     \
     } while( 0 )
 
 /*
@@ -873,10 +850,10 @@
         uint32_t Y[4];
     } t;
 
-    GET_UINT32_LE( t.X[0], input,  0 ); t.X[0] ^= *RK++;
-    GET_UINT32_LE( t.X[1], input,  4 ); t.X[1] ^= *RK++;
-    GET_UINT32_LE( t.X[2], input,  8 ); t.X[2] ^= *RK++;
-    GET_UINT32_LE( t.X[3], input, 12 ); t.X[3] ^= *RK++;
+    t.X[0] = MBEDTLS_GET_UINT32_LE( input,  0 ); t.X[0] ^= *RK++;
+    t.X[1] = MBEDTLS_GET_UINT32_LE( input,  4 ); t.X[1] ^= *RK++;
+    t.X[2] = MBEDTLS_GET_UINT32_LE( input,  8 ); t.X[2] ^= *RK++;
+    t.X[3] = MBEDTLS_GET_UINT32_LE( input, 12 ); t.X[3] ^= *RK++;
 
     for( i = ( ctx->nr >> 1 ) - 1; i > 0; i-- )
     {
@@ -887,33 +864,33 @@
     AES_FROUND( t.Y[0], t.Y[1], t.Y[2], t.Y[3], t.X[0], t.X[1], t.X[2], t.X[3] );
 
     t.X[0] = *RK++ ^ \
-            ( (uint32_t) FSb[ ( t.Y[0]       ) & 0xFF ]       ) ^
-            ( (uint32_t) FSb[ ( t.Y[1] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) FSb[ ( t.Y[2] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) FSb[ ( t.Y[3] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_0( t.Y[0] ) ]       ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_1( t.Y[1] ) ] <<  8 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_2( t.Y[2] ) ] << 16 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_3( t.Y[3] ) ] << 24 );
 
     t.X[1] = *RK++ ^ \
-            ( (uint32_t) FSb[ ( t.Y[1]       ) & 0xFF ]       ) ^
-            ( (uint32_t) FSb[ ( t.Y[2] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) FSb[ ( t.Y[3] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) FSb[ ( t.Y[0] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_0( t.Y[1] ) ]       ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_1( t.Y[2] ) ] <<  8 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_2( t.Y[3] ) ] << 16 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_3( t.Y[0] ) ] << 24 );
 
     t.X[2] = *RK++ ^ \
-            ( (uint32_t) FSb[ ( t.Y[2]       ) & 0xFF ]       ) ^
-            ( (uint32_t) FSb[ ( t.Y[3] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) FSb[ ( t.Y[0] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) FSb[ ( t.Y[1] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_0( t.Y[2] ) ]       ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_1( t.Y[3] ) ] <<  8 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_2( t.Y[0] ) ] << 16 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_3( t.Y[1] ) ] << 24 );
 
     t.X[3] = *RK++ ^ \
-            ( (uint32_t) FSb[ ( t.Y[3]       ) & 0xFF ]       ) ^
-            ( (uint32_t) FSb[ ( t.Y[0] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) FSb[ ( t.Y[1] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) FSb[ ( t.Y[2] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_0( t.Y[3] ) ]       ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_1( t.Y[0] ) ] <<  8 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_2( t.Y[1] ) ] << 16 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_3( t.Y[2] ) ] << 24 );
 
-    PUT_UINT32_LE( t.X[0], output,  0 );
-    PUT_UINT32_LE( t.X[1], output,  4 );
-    PUT_UINT32_LE( t.X[2], output,  8 );
-    PUT_UINT32_LE( t.X[3], output, 12 );
+    MBEDTLS_PUT_UINT32_LE( t.X[0], output,  0 );
+    MBEDTLS_PUT_UINT32_LE( t.X[1], output,  4 );
+    MBEDTLS_PUT_UINT32_LE( t.X[2], output,  8 );
+    MBEDTLS_PUT_UINT32_LE( t.X[3], output, 12 );
 
     mbedtls_platform_zeroize( &t, sizeof( t ) );
 
@@ -937,10 +914,10 @@
         uint32_t Y[4];
     } t;
 
-    GET_UINT32_LE( t.X[0], input,  0 ); t.X[0] ^= *RK++;
-    GET_UINT32_LE( t.X[1], input,  4 ); t.X[1] ^= *RK++;
-    GET_UINT32_LE( t.X[2], input,  8 ); t.X[2] ^= *RK++;
-    GET_UINT32_LE( t.X[3], input, 12 ); t.X[3] ^= *RK++;
+    t.X[0] = MBEDTLS_GET_UINT32_LE( input,  0 ); t.X[0] ^= *RK++;
+    t.X[1] = MBEDTLS_GET_UINT32_LE( input,  4 ); t.X[1] ^= *RK++;
+    t.X[2] = MBEDTLS_GET_UINT32_LE( input,  8 ); t.X[2] ^= *RK++;
+    t.X[3] = MBEDTLS_GET_UINT32_LE( input, 12 ); t.X[3] ^= *RK++;
 
     for( i = ( ctx->nr >> 1 ) - 1; i > 0; i-- )
     {
@@ -951,33 +928,33 @@
     AES_RROUND( t.Y[0], t.Y[1], t.Y[2], t.Y[3], t.X[0], t.X[1], t.X[2], t.X[3] );
 
     t.X[0] = *RK++ ^ \
-            ( (uint32_t) RSb[ ( t.Y[0]       ) & 0xFF ]       ) ^
-            ( (uint32_t) RSb[ ( t.Y[3] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) RSb[ ( t.Y[2] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) RSb[ ( t.Y[1] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_0( t.Y[0] ) ]       ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_1( t.Y[3] ) ] <<  8 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_2( t.Y[2] ) ] << 16 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_3( t.Y[1] ) ] << 24 );
 
     t.X[1] = *RK++ ^ \
-            ( (uint32_t) RSb[ ( t.Y[1]       ) & 0xFF ]       ) ^
-            ( (uint32_t) RSb[ ( t.Y[0] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) RSb[ ( t.Y[3] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) RSb[ ( t.Y[2] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_0( t.Y[1] ) ]       ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_1( t.Y[0] ) ] <<  8 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_2( t.Y[3] ) ] << 16 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_3( t.Y[2] ) ] << 24 );
 
     t.X[2] = *RK++ ^ \
-            ( (uint32_t) RSb[ ( t.Y[2]       ) & 0xFF ]       ) ^
-            ( (uint32_t) RSb[ ( t.Y[1] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) RSb[ ( t.Y[0] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) RSb[ ( t.Y[3] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_0( t.Y[2] ) ]       ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_1( t.Y[1] ) ] <<  8 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_2( t.Y[0] ) ] << 16 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_3( t.Y[3] ) ] << 24 );
 
     t.X[3] = *RK++ ^ \
-            ( (uint32_t) RSb[ ( t.Y[3]       ) & 0xFF ]       ) ^
-            ( (uint32_t) RSb[ ( t.Y[2] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) RSb[ ( t.Y[1] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) RSb[ ( t.Y[0] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_0( t.Y[3] ) ]       ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_1( t.Y[2] ) ] <<  8 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_2( t.Y[1] ) ] << 16 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_3( t.Y[0] ) ] << 24 );
 
-    PUT_UINT32_LE( t.X[0], output,  0 );
-    PUT_UINT32_LE( t.X[1], output,  4 );
-    PUT_UINT32_LE( t.X[2], output,  8 );
-    PUT_UINT32_LE( t.X[3], output, 12 );
+    MBEDTLS_PUT_UINT32_LE( t.X[0], output,  0 );
+    MBEDTLS_PUT_UINT32_LE( t.X[1], output,  4 );
+    MBEDTLS_PUT_UINT32_LE( t.X[2], output,  8 );
+    MBEDTLS_PUT_UINT32_LE( t.X[3], output, 12 );
 
     mbedtls_platform_zeroize( &t, sizeof( t ) );
 
@@ -1097,35 +1074,6 @@
 
 #if defined(MBEDTLS_CIPHER_MODE_XTS)
 
-/* Endianess with 64 bits values */
-#ifndef GET_UINT64_LE
-#define GET_UINT64_LE(n,b,i)                            \
-{                                                       \
-    (n) = ( (uint64_t) (b)[(i) + 7] << 56 )             \
-        | ( (uint64_t) (b)[(i) + 6] << 48 )             \
-        | ( (uint64_t) (b)[(i) + 5] << 40 )             \
-        | ( (uint64_t) (b)[(i) + 4] << 32 )             \
-        | ( (uint64_t) (b)[(i) + 3] << 24 )             \
-        | ( (uint64_t) (b)[(i) + 2] << 16 )             \
-        | ( (uint64_t) (b)[(i) + 1] <<  8 )             \
-        | ( (uint64_t) (b)[(i)    ]       );            \
-}
-#endif
-
-#ifndef PUT_UINT64_LE
-#define PUT_UINT64_LE(n,b,i)                            \
-{                                                       \
-    (b)[(i) + 7] = (unsigned char) ( (n) >> 56 );       \
-    (b)[(i) + 6] = (unsigned char) ( (n) >> 48 );       \
-    (b)[(i) + 5] = (unsigned char) ( (n) >> 40 );       \
-    (b)[(i) + 4] = (unsigned char) ( (n) >> 32 );       \
-    (b)[(i) + 3] = (unsigned char) ( (n) >> 24 );       \
-    (b)[(i) + 2] = (unsigned char) ( (n) >> 16 );       \
-    (b)[(i) + 1] = (unsigned char) ( (n) >>  8 );       \
-    (b)[(i)    ] = (unsigned char) ( (n)       );       \
-}
-#endif
-
 typedef unsigned char mbedtls_be128[16];
 
 /*
@@ -1141,14 +1089,14 @@
 {
     uint64_t a, b, ra, rb;
 
-    GET_UINT64_LE( a, x, 0 );
-    GET_UINT64_LE( b, x, 8 );
+    a = MBEDTLS_GET_UINT64_LE( x, 0 );
+    b = MBEDTLS_GET_UINT64_LE( x, 8 );
 
     ra = ( a << 1 )  ^ 0x0087 >> ( 8 - ( ( b >> 63 ) << 3 ) );
     rb = ( a >> 63 ) | ( b << 1 );
 
-    PUT_UINT64_LE( ra, r, 0 );
-    PUT_UINT64_LE( rb, r, 8 );
+    MBEDTLS_PUT_UINT64_LE( ra, r, 0 );
+    MBEDTLS_PUT_UINT64_LE( rb, r, 8 );
 }
 
 /*
diff --git a/library/aria.c b/library/aria.c
index a5786b3..bc05c4a 100644
--- a/library/aria.c
+++ b/library/aria.c
@@ -56,29 +56,6 @@
     MBEDTLS_INTERNAL_VALIDATE( cond )
 
 /*
- * 32-bit integer manipulation macros (little endian)
- */
-#ifndef GET_UINT32_LE
-#define GET_UINT32_LE( n, b, i )                \
-{                                               \
-    (n) = ( (uint32_t) (b)[(i)    ]       )     \
-        | ( (uint32_t) (b)[(i) + 1] <<  8 )     \
-        | ( (uint32_t) (b)[(i) + 2] << 16 )     \
-        | ( (uint32_t) (b)[(i) + 3] << 24 );    \
-}
-#endif
-
-#ifndef PUT_UINT32_LE
-#define PUT_UINT32_LE( n, b, i )                                \
-{                                                               \
-    (b)[(i)    ] = (unsigned char) ( ( (n)       ) & 0xFF );    \
-    (b)[(i) + 1] = (unsigned char) ( ( (n) >>  8 ) & 0xFF );    \
-    (b)[(i) + 2] = (unsigned char) ( ( (n) >> 16 ) & 0xFF );    \
-    (b)[(i) + 3] = (unsigned char) ( ( (n) >> 24 ) & 0xFF );    \
-}
-#endif
-
-/*
  * modify byte order: ( A B C D ) -> ( B A D C ), i.e. swap pairs of bytes
  *
  * This is submatrix P1 in [1] Appendix B.1
@@ -235,22 +212,22 @@
                             const uint8_t sa[256], const uint8_t sb[256],
                             const uint8_t sc[256], const uint8_t sd[256] )
 {
-    *a = ( (uint32_t) sa[ *a        & 0xFF]       ) ^
-         (((uint32_t) sb[(*a >>  8) & 0xFF]) <<  8) ^
-         (((uint32_t) sc[(*a >> 16) & 0xFF]) << 16) ^
-         (((uint32_t) sd[ *a >> 24        ]) << 24);
-    *b = ( (uint32_t) sa[ *b        & 0xFF]       ) ^
-         (((uint32_t) sb[(*b >>  8) & 0xFF]) <<  8) ^
-         (((uint32_t) sc[(*b >> 16) & 0xFF]) << 16) ^
-         (((uint32_t) sd[ *b >> 24        ]) << 24);
-    *c = ( (uint32_t) sa[ *c        & 0xFF]       ) ^
-         (((uint32_t) sb[(*c >>  8) & 0xFF]) <<  8) ^
-         (((uint32_t) sc[(*c >> 16) & 0xFF]) << 16) ^
-         (((uint32_t) sd[ *c >> 24        ]) << 24);
-    *d = ( (uint32_t) sa[ *d        & 0xFF]       ) ^
-         (((uint32_t) sb[(*d >>  8) & 0xFF]) <<  8) ^
-         (((uint32_t) sc[(*d >> 16) & 0xFF]) << 16) ^
-         (((uint32_t) sd[ *d >> 24        ]) << 24);
+    *a = ( (uint32_t) sa[ MBEDTLS_BYTE_0( *a ) ]       ) ^
+         (((uint32_t) sb[ MBEDTLS_BYTE_1( *a ) ]) <<  8) ^
+         (((uint32_t) sc[ MBEDTLS_BYTE_2( *a ) ]) << 16) ^
+         (((uint32_t) sd[ MBEDTLS_BYTE_3( *a ) ]) << 24);
+    *b = ( (uint32_t) sa[ MBEDTLS_BYTE_0( *b ) ]       ) ^
+         (((uint32_t) sb[ MBEDTLS_BYTE_1( *b ) ]) <<  8) ^
+         (((uint32_t) sc[ MBEDTLS_BYTE_2( *b ) ]) << 16) ^
+         (((uint32_t) sd[ MBEDTLS_BYTE_3( *b ) ]) << 24);
+    *c = ( (uint32_t) sa[ MBEDTLS_BYTE_0( *c ) ]       ) ^
+         (((uint32_t) sb[ MBEDTLS_BYTE_1( *c ) ]) <<  8) ^
+         (((uint32_t) sc[ MBEDTLS_BYTE_2( *c ) ]) << 16) ^
+         (((uint32_t) sd[ MBEDTLS_BYTE_3( *c ) ]) << 24);
+    *d = ( (uint32_t) sa[ MBEDTLS_BYTE_0( *d ) ]       ) ^
+         (((uint32_t) sb[ MBEDTLS_BYTE_1( *d ) ]) <<  8) ^
+         (((uint32_t) sc[ MBEDTLS_BYTE_2( *d ) ]) << 16) ^
+         (((uint32_t) sd[ MBEDTLS_BYTE_3( *d ) ]) << 24);
 }
 
 /*
@@ -408,7 +385,8 @@
  * Big endian 128-bit rotation: r = a ^ (b <<< n), used only in key setup.
  *
  * We chose to store bytes into 32-bit words in little-endian format (see
- * GET/PUT_UINT32_LE) so we need to reverse bytes here.
+ * MBEDTLS_GET_UINT32_LE / MBEDTLS_PUT_UINT32_LE ) so we need to reverse
+ * bytes here.
  */
 static void aria_rot128( uint32_t r[4], const uint32_t a[4],
                          const uint32_t b[4], uint8_t n )
@@ -456,21 +434,21 @@
         return( MBEDTLS_ERR_ARIA_BAD_INPUT_DATA );
 
     /* Copy key to W0 (and potential remainder to W1) */
-    GET_UINT32_LE( w[0][0], key,  0 );
-    GET_UINT32_LE( w[0][1], key,  4 );
-    GET_UINT32_LE( w[0][2], key,  8 );
-    GET_UINT32_LE( w[0][3], key, 12 );
+    w[0][0] = MBEDTLS_GET_UINT32_LE( key,  0 );
+    w[0][1] = MBEDTLS_GET_UINT32_LE( key,  4 );
+    w[0][2] = MBEDTLS_GET_UINT32_LE( key,  8 );
+    w[0][3] = MBEDTLS_GET_UINT32_LE( key, 12 );
 
     memset( w[1], 0, 16 );
     if( keybits >= 192 )
     {
-        GET_UINT32_LE( w[1][0], key, 16 );  // 192 bit key
-        GET_UINT32_LE( w[1][1], key, 20 );
+        w[1][0] = MBEDTLS_GET_UINT32_LE( key, 16 );  // 192 bit key
+        w[1][1] = MBEDTLS_GET_UINT32_LE( key, 20 );
     }
     if( keybits == 256 )
     {
-        GET_UINT32_LE( w[1][2], key, 24 );  // 256 bit key
-        GET_UINT32_LE( w[1][3], key, 28 );
+        w[1][2] = MBEDTLS_GET_UINT32_LE( key, 24 );  // 256 bit key
+        w[1][3] = MBEDTLS_GET_UINT32_LE( key, 28 );
     }
 
     i = ( keybits - 128 ) >> 6;             // index: 0, 1, 2
@@ -547,10 +525,10 @@
     ARIA_VALIDATE_RET( input != NULL );
     ARIA_VALIDATE_RET( output != NULL );
 
-    GET_UINT32_LE( a, input,  0 );
-    GET_UINT32_LE( b, input,  4 );
-    GET_UINT32_LE( c, input,  8 );
-    GET_UINT32_LE( d, input, 12 );
+    a = MBEDTLS_GET_UINT32_LE( input,  0 );
+    b = MBEDTLS_GET_UINT32_LE( input,  4 );
+    c = MBEDTLS_GET_UINT32_LE( input,  8 );
+    d = MBEDTLS_GET_UINT32_LE( input, 12 );
 
     i = 0;
     while( 1 )
@@ -582,10 +560,10 @@
     c ^= ctx->rk[i][2];
     d ^= ctx->rk[i][3];
 
-    PUT_UINT32_LE( a, output,  0 );
-    PUT_UINT32_LE( b, output,  4 );
-    PUT_UINT32_LE( c, output,  8 );
-    PUT_UINT32_LE( d, output, 12 );
+    MBEDTLS_PUT_UINT32_LE( a, output,  0 );
+    MBEDTLS_PUT_UINT32_LE( b, output,  4 );
+    MBEDTLS_PUT_UINT32_LE( c, output,  8 );
+    MBEDTLS_PUT_UINT32_LE( d, output, 12 );
 
     return( 0 );
 }
diff --git a/library/asn1write.c b/library/asn1write.c
index 0289e89..dc61854 100644
--- a/library/asn1write.c
+++ b/library/asn1write.c
@@ -60,8 +60,8 @@
         if( *p - start < 3 )
             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
 
-        *--(*p) = ( len       ) & 0xFF;
-        *--(*p) = ( len >>  8 ) & 0xFF;
+        *--(*p) = MBEDTLS_BYTE_0( len );
+        *--(*p) = MBEDTLS_BYTE_1( len );
         *--(*p) = 0x82;
         return( 3 );
     }
@@ -71,9 +71,9 @@
         if( *p - start < 4 )
             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
 
-        *--(*p) = ( len       ) & 0xFF;
-        *--(*p) = ( len >>  8 ) & 0xFF;
-        *--(*p) = ( len >> 16 ) & 0xFF;
+        *--(*p) = MBEDTLS_BYTE_0( len );
+        *--(*p) = MBEDTLS_BYTE_1( len );
+        *--(*p) = MBEDTLS_BYTE_2( len );
         *--(*p) = 0x83;
         return( 4 );
     }
@@ -85,10 +85,10 @@
         if( *p - start < 5 )
             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
 
-        *--(*p) = ( len       ) & 0xFF;
-        *--(*p) = ( len >>  8 ) & 0xFF;
-        *--(*p) = ( len >> 16 ) & 0xFF;
-        *--(*p) = ( len >> 24 ) & 0xFF;
+        *--(*p) = MBEDTLS_BYTE_0( len );
+        *--(*p) = MBEDTLS_BYTE_1( len );
+        *--(*p) = MBEDTLS_BYTE_2( len );
+        *--(*p) = MBEDTLS_BYTE_3( len );
         *--(*p) = 0x84;
         return( 5 );
     }
diff --git a/library/base64.c b/library/base64.c
index 1a05226..9cf5dd4 100644
--- a/library/base64.c
+++ b/library/base64.c
@@ -319,9 +319,9 @@
         if( ++n == 4 )
         {
             n = 0;
-            if( j > 0 ) *p++ = (unsigned char)( x >> 16 );
-            if( j > 1 ) *p++ = (unsigned char)( x >>  8 );
-            if( j > 2 ) *p++ = (unsigned char)( x       );
+            if( j > 0 ) *p++ = MBEDTLS_BYTE_2( x );
+            if( j > 1 ) *p++ = MBEDTLS_BYTE_1( x );
+            if( j > 2 ) *p++ = MBEDTLS_BYTE_0( x );
         }
     }
 
diff --git a/library/camellia.c b/library/camellia.c
index f7e0136..29d730a 100644
--- a/library/camellia.c
+++ b/library/camellia.c
@@ -49,29 +49,6 @@
 #define CAMELLIA_VALIDATE( cond )                                           \
     MBEDTLS_INTERNAL_VALIDATE( cond )
 
-/*
- * 32-bit integer manipulation macros (big endian)
- */
-#ifndef GET_UINT32_BE
-#define GET_UINT32_BE(n,b,i)                            \
-{                                                       \
-    (n) = ( (uint32_t) (b)[(i)    ] << 24 )             \
-        | ( (uint32_t) (b)[(i) + 1] << 16 )             \
-        | ( (uint32_t) (b)[(i) + 2] <<  8 )             \
-        | ( (uint32_t) (b)[(i) + 3]       );            \
-}
-#endif
-
-#ifndef PUT_UINT32_BE
-#define PUT_UINT32_BE(n,b,i)                            \
-{                                                       \
-    (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
-    (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
-    (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
-    (b)[(i) + 3] = (unsigned char) ( (n)       );       \
-}
-#endif
-
 static const unsigned char SIGMA_CHARS[6][8] =
 {
     { 0xa0, 0x9e, 0x66, 0x7f, 0x3b, 0xcc, 0x90, 0x8b },
@@ -301,14 +278,14 @@
     I0 = x[0] ^ k[0];
     I1 = x[1] ^ k[1];
 
-    I0 = ((uint32_t) SBOX1((I0 >> 24) & 0xFF) << 24) |
-         ((uint32_t) SBOX2((I0 >> 16) & 0xFF) << 16) |
-         ((uint32_t) SBOX3((I0 >>  8) & 0xFF) <<  8) |
-         ((uint32_t) SBOX4((I0      ) & 0xFF)      );
-    I1 = ((uint32_t) SBOX2((I1 >> 24) & 0xFF) << 24) |
-         ((uint32_t) SBOX3((I1 >> 16) & 0xFF) << 16) |
-         ((uint32_t) SBOX4((I1 >>  8) & 0xFF) <<  8) |
-         ((uint32_t) SBOX1((I1      ) & 0xFF)      );
+    I0 = ((uint32_t) SBOX1( MBEDTLS_BYTE_3( I0 )) << 24) |
+         ((uint32_t) SBOX2( MBEDTLS_BYTE_2( I0 )) << 16) |
+         ((uint32_t) SBOX3( MBEDTLS_BYTE_1( I0 )) <<  8) |
+         ((uint32_t) SBOX4( MBEDTLS_BYTE_0( I0 ))      );
+    I1 = ((uint32_t) SBOX2( MBEDTLS_BYTE_3( I1 )) << 24) |
+         ((uint32_t) SBOX3( MBEDTLS_BYTE_2( I1 )) << 16) |
+         ((uint32_t) SBOX4( MBEDTLS_BYTE_1( I1 )) <<  8) |
+         ((uint32_t) SBOX1( MBEDTLS_BYTE_0( I1 ))      );
 
     I0 ^= (I1 << 8) | (I1 >> 24);
     I1 ^= (I0 << 16) | (I0 >> 16);
@@ -376,8 +353,8 @@
      * Prepare SIGMA values
      */
     for( i = 0; i < 6; i++ ) {
-        GET_UINT32_BE( SIGMA[i][0], SIGMA_CHARS[i], 0 );
-        GET_UINT32_BE( SIGMA[i][1], SIGMA_CHARS[i], 4 );
+        SIGMA[i][0] = MBEDTLS_GET_UINT32_BE( SIGMA_CHARS[i], 0 );
+        SIGMA[i][1] = MBEDTLS_GET_UINT32_BE( SIGMA_CHARS[i], 4 );
     }
 
     /*
@@ -388,7 +365,7 @@
 
     /* Store KL, KR */
     for( i = 0; i < 8; i++ )
-        GET_UINT32_BE( KC[i], t, i * 4 );
+        KC[i] = MBEDTLS_GET_UINT32_BE( t, i * 4 );
 
     /* Generate KA */
     for( i = 0; i < 4; ++i )
@@ -514,10 +491,10 @@
     NR = ctx->nr;
     RK = ctx->rk;
 
-    GET_UINT32_BE( X[0], input,  0 );
-    GET_UINT32_BE( X[1], input,  4 );
-    GET_UINT32_BE( X[2], input,  8 );
-    GET_UINT32_BE( X[3], input, 12 );
+    X[0] = MBEDTLS_GET_UINT32_BE( input,  0 );
+    X[1] = MBEDTLS_GET_UINT32_BE( input,  4 );
+    X[2] = MBEDTLS_GET_UINT32_BE( input,  8 );
+    X[3] = MBEDTLS_GET_UINT32_BE( input, 12 );
 
     X[0] ^= *RK++;
     X[1] ^= *RK++;
@@ -552,10 +529,10 @@
     X[0] ^= *RK++;
     X[1] ^= *RK++;
 
-    PUT_UINT32_BE( X[2], output,  0 );
-    PUT_UINT32_BE( X[3], output,  4 );
-    PUT_UINT32_BE( X[0], output,  8 );
-    PUT_UINT32_BE( X[1], output, 12 );
+    MBEDTLS_PUT_UINT32_BE( X[2], output,  0 );
+    MBEDTLS_PUT_UINT32_BE( X[3], output,  4 );
+    MBEDTLS_PUT_UINT32_BE( X[0], output,  8 );
+    MBEDTLS_PUT_UINT32_BE( X[1], output, 12 );
 
     return( 0 );
 }
diff --git a/library/ccm.c b/library/ccm.c
index 1e88f90..0a90461 100644
--- a/library/ccm.c
+++ b/library/ccm.c
@@ -171,7 +171,7 @@
     ctx->y[0] |= ctx->q - 1;
 
     for( i = 0, len_left = ctx->plaintext_len; i < ctx->q; i++, len_left >>= 8 )
-        ctx->y[15-i] = (unsigned char)( len_left & 0xFF );
+        ctx->y[15-i] = MBEDTLS_BYTE_0( len_left );
 
     if( len_left > 0 )
     {
diff --git a/library/chacha20.c b/library/chacha20.c
index 78467d3..658f046 100644
--- a/library/chacha20.c
+++ b/library/chacha20.c
@@ -54,13 +54,6 @@
 #define CHACHA20_VALIDATE( cond )                                           \
     MBEDTLS_INTERNAL_VALIDATE( cond )
 
-#define BYTES_TO_U32_LE( data, offset )                           \
-    ( (uint32_t) (data)[offset]                                   \
-      | (uint32_t) ( (uint32_t) (data)[( offset ) + 1] << 8 )     \
-      | (uint32_t) ( (uint32_t) (data)[( offset ) + 2] << 16 )    \
-      | (uint32_t) ( (uint32_t) (data)[( offset ) + 3] << 24 )    \
-    )
-
 #define ROTL32( value, amount ) \
     ( (uint32_t) ( (value) << (amount) ) | ( (value) >> ( 32 - (amount) ) ) )
 
@@ -171,10 +164,7 @@
     {
         size_t offset = i * 4U;
 
-        keystream[offset     ] = (unsigned char)( working_state[i]       );
-        keystream[offset + 1U] = (unsigned char)( working_state[i] >>  8 );
-        keystream[offset + 2U] = (unsigned char)( working_state[i] >> 16 );
-        keystream[offset + 3U] = (unsigned char)( working_state[i] >> 24 );
+        MBEDTLS_PUT_UINT32_LE(working_state[i], keystream, offset);
     }
 
     mbedtls_platform_zeroize( working_state, sizeof( working_state ) );
@@ -212,14 +202,14 @@
     ctx->state[3] = 0x6b206574;
 
     /* Set key */
-    ctx->state[4]  = BYTES_TO_U32_LE( key, 0 );
-    ctx->state[5]  = BYTES_TO_U32_LE( key, 4 );
-    ctx->state[6]  = BYTES_TO_U32_LE( key, 8 );
-    ctx->state[7]  = BYTES_TO_U32_LE( key, 12 );
-    ctx->state[8]  = BYTES_TO_U32_LE( key, 16 );
-    ctx->state[9]  = BYTES_TO_U32_LE( key, 20 );
-    ctx->state[10] = BYTES_TO_U32_LE( key, 24 );
-    ctx->state[11] = BYTES_TO_U32_LE( key, 28 );
+    ctx->state[4]  = MBEDTLS_GET_UINT32_LE( key, 0 );
+    ctx->state[5]  = MBEDTLS_GET_UINT32_LE( key, 4 );
+    ctx->state[6]  = MBEDTLS_GET_UINT32_LE( key, 8 );
+    ctx->state[7]  = MBEDTLS_GET_UINT32_LE( key, 12 );
+    ctx->state[8]  = MBEDTLS_GET_UINT32_LE( key, 16 );
+    ctx->state[9]  = MBEDTLS_GET_UINT32_LE( key, 20 );
+    ctx->state[10] = MBEDTLS_GET_UINT32_LE( key, 24 );
+    ctx->state[11] = MBEDTLS_GET_UINT32_LE( key, 28 );
 
     return( 0 );
 }
@@ -235,9 +225,9 @@
     ctx->state[12] = counter;
 
     /* Nonce */
-    ctx->state[13] = BYTES_TO_U32_LE( nonce, 0 );
-    ctx->state[14] = BYTES_TO_U32_LE( nonce, 4 );
-    ctx->state[15] = BYTES_TO_U32_LE( nonce, 8 );
+    ctx->state[13] = MBEDTLS_GET_UINT32_LE( nonce, 0 );
+    ctx->state[14] = MBEDTLS_GET_UINT32_LE( nonce, 4 );
+    ctx->state[15] = MBEDTLS_GET_UINT32_LE( nonce, 8 );
 
     mbedtls_platform_zeroize( ctx->keystream8, sizeof( ctx->keystream8 ) );
 
diff --git a/library/chachapoly.c b/library/chachapoly.c
index 77d5477..dc75b20 100644
--- a/library/chachapoly.c
+++ b/library/chachapoly.c
@@ -263,22 +263,8 @@
     /* The lengths of the AAD and ciphertext are processed by
      * Poly1305 as the final 128-bit block, encoded as little-endian integers.
      */
-    len_block[ 0] = (unsigned char)( ctx->aad_len       );
-    len_block[ 1] = (unsigned char)( ctx->aad_len >>  8 );
-    len_block[ 2] = (unsigned char)( ctx->aad_len >> 16 );
-    len_block[ 3] = (unsigned char)( ctx->aad_len >> 24 );
-    len_block[ 4] = (unsigned char)( ctx->aad_len >> 32 );
-    len_block[ 5] = (unsigned char)( ctx->aad_len >> 40 );
-    len_block[ 6] = (unsigned char)( ctx->aad_len >> 48 );
-    len_block[ 7] = (unsigned char)( ctx->aad_len >> 56 );
-    len_block[ 8] = (unsigned char)( ctx->ciphertext_len       );
-    len_block[ 9] = (unsigned char)( ctx->ciphertext_len >>  8 );
-    len_block[10] = (unsigned char)( ctx->ciphertext_len >> 16 );
-    len_block[11] = (unsigned char)( ctx->ciphertext_len >> 24 );
-    len_block[12] = (unsigned char)( ctx->ciphertext_len >> 32 );
-    len_block[13] = (unsigned char)( ctx->ciphertext_len >> 40 );
-    len_block[14] = (unsigned char)( ctx->ciphertext_len >> 48 );
-    len_block[15] = (unsigned char)( ctx->ciphertext_len >> 56 );
+    MBEDTLS_PUT_UINT64_LE(ctx->aad_len, len_block, 0);
+    MBEDTLS_PUT_UINT64_LE(ctx->ciphertext_len, len_block, 8);
 
     ret = mbedtls_poly1305_update( &ctx->poly1305_ctx, len_block, 16U );
     if( ret != 0 )
diff --git a/library/common.h b/library/common.h
index 9e4b031..780ce37 100644
--- a/library/common.h
+++ b/library/common.h
@@ -25,6 +25,8 @@
 
 #include "mbedtls/build_info.h"
 
+#include <stdint.h>
+
 /** Helper to define a function as static except when building invasive tests.
  *
  * If a function is only used inside its own source file and should be
@@ -66,4 +68,254 @@
  */
 #define MBEDTLS_ALLOW_PRIVATE_ACCESS
 
+/** Byte Reading Macros
+ *
+ * Given a multi-byte integer \p x, MBEDTLS_BYTE_n retrieves the n-th
+ * byte from x, where byte 0 is the least significant byte.
+ */
+#define MBEDTLS_BYTE_0( x ) ( (uint8_t) (   ( x )         & 0xff ) )
+#define MBEDTLS_BYTE_1( x ) ( (uint8_t) ( ( ( x ) >> 8  ) & 0xff ) )
+#define MBEDTLS_BYTE_2( x ) ( (uint8_t) ( ( ( x ) >> 16 ) & 0xff ) )
+#define MBEDTLS_BYTE_3( x ) ( (uint8_t) ( ( ( x ) >> 24 ) & 0xff ) )
+#define MBEDTLS_BYTE_4( x ) ( (uint8_t) ( ( ( x ) >> 32 ) & 0xff ) )
+#define MBEDTLS_BYTE_5( x ) ( (uint8_t) ( ( ( x ) >> 40 ) & 0xff ) )
+#define MBEDTLS_BYTE_6( x ) ( (uint8_t) ( ( ( x ) >> 48 ) & 0xff ) )
+#define MBEDTLS_BYTE_7( x ) ( (uint8_t) ( ( ( x ) >> 56 ) & 0xff ) )
+
+/**
+ * Get the unsigned 32 bits integer corresponding to four bytes in
+ * big-endian order (MSB first).
+ *
+ * \param   data    Base address of the memory to get the four bytes from.
+ * \param   offset  Offset from \p base of the first and most significant
+ *                  byte of the four bytes to build the 32 bits unsigned
+ *                  integer from.
+ */
+#ifndef MBEDTLS_GET_UINT32_BE
+#define MBEDTLS_GET_UINT32_BE( data , offset )                  \
+    (                                                           \
+          ( (uint32_t) ( data )[( offset )    ] << 24 )         \
+        | ( (uint32_t) ( data )[( offset ) + 1] << 16 )         \
+        | ( (uint32_t) ( data )[( offset ) + 2] <<  8 )         \
+        | ( (uint32_t) ( data )[( offset ) + 3]       )         \
+    )
+#endif
+
+/**
+ * Put in memory a 32 bits unsigned integer in big-endian order.
+ *
+ * \param   n       32 bits unsigned integer to put in memory.
+ * \param   data    Base address of the memory where to put the 32
+ *                  bits unsigned integer in.
+ * \param   offset  Offset from \p base where to put the most significant
+ *                  byte of the 32 bits unsigned integer \p n.
+ */
+#ifndef MBEDTLS_PUT_UINT32_BE
+#define MBEDTLS_PUT_UINT32_BE( n, data, offset )                \
+{                                                               \
+    ( data )[( offset )    ] = MBEDTLS_BYTE_3( n );             \
+    ( data )[( offset ) + 1] = MBEDTLS_BYTE_2( n );             \
+    ( data )[( offset ) + 2] = MBEDTLS_BYTE_1( n );             \
+    ( data )[( offset ) + 3] = MBEDTLS_BYTE_0( n );             \
+}
+#endif
+
+/**
+ * Get the unsigned 32 bits integer corresponding to four bytes in
+ * little-endian order (LSB first).
+ *
+ * \param   data    Base address of the memory to get the four bytes from.
+ * \param   offset  Offset from \p base of the first and least significant
+ *                  byte of the four bytes to build the 32 bits unsigned
+ *                  integer from.
+ */
+#ifndef MBEDTLS_GET_UINT32_LE
+#define MBEDTLS_GET_UINT32_LE( data, offset )                   \
+    (                                                           \
+          ( (uint32_t) ( data )[( offset )    ]       )         \
+        | ( (uint32_t) ( data )[( offset ) + 1] <<  8 )         \
+        | ( (uint32_t) ( data )[( offset ) + 2] << 16 )         \
+        | ( (uint32_t) ( data )[( offset ) + 3] << 24 )         \
+    )
+#endif
+
+/**
+ * Put in memory a 32 bits unsigned integer in little-endian order.
+ *
+ * \param   n       32 bits unsigned integer to put in memory.
+ * \param   data    Base address of the memory where to put the 32
+ *                  bits unsigned integer in.
+ * \param   offset  Offset from \p base where to put the least significant
+ *                  byte of the 32 bits unsigned integer \p n.
+ */
+#ifndef MBEDTLS_PUT_UINT32_LE
+#define MBEDTLS_PUT_UINT32_LE( n, data, offset )                \
+{                                                               \
+    ( data )[( offset )    ] = MBEDTLS_BYTE_0( n );             \
+    ( data )[( offset ) + 1] = MBEDTLS_BYTE_1( n );             \
+    ( data )[( offset ) + 2] = MBEDTLS_BYTE_2( n );             \
+    ( data )[( offset ) + 3] = MBEDTLS_BYTE_3( n );             \
+}
+#endif
+
+/**
+ * Get the unsigned 16 bits integer corresponding to two bytes in
+ * little-endian order (LSB first).
+ *
+ * \param   data    Base address of the memory to get the two bytes from.
+ * \param   offset  Offset from \p base of the first and least significant
+ *                  byte of the two bytes to build the 16 bits unsigned
+ *                  integer from.
+ */
+#ifndef MBEDTLS_GET_UINT16_LE
+#define MBEDTLS_GET_UINT16_LE( data, offset )                   \
+    (                                                           \
+          ( (uint16_t) ( data )[( offset )    ]       )         \
+        | ( (uint16_t) ( data )[( offset ) + 1] <<  8 )         \
+    )
+#endif
+
+/**
+ * Put in memory a 16 bits unsigned integer in little-endian order.
+ *
+ * \param   n       16 bits unsigned integer to put in memory.
+ * \param   data    Base address of the memory where to put the 16
+ *                  bits unsigned integer in.
+ * \param   offset  Offset from \p base where to put the least significant
+ *                  byte of the 16 bits unsigned integer \p n.
+ */
+#ifndef MBEDTLS_PUT_UINT16_LE
+#define MBEDTLS_PUT_UINT16_LE( n, data, offset )                \
+{                                                               \
+    ( data )[( offset )    ] = MBEDTLS_BYTE_0( n );             \
+    ( data )[( offset ) + 1] = MBEDTLS_BYTE_1( n );             \
+}
+#endif
+
+/**
+ * Get the unsigned 16 bits integer corresponding to two bytes in
+ * big-endian order (MSB first).
+ *
+ * \param   data    Base address of the memory to get the two bytes from.
+ * \param   offset  Offset from \p base of the first and most significant
+ *                  byte of the two bytes to build the 16 bits unsigned
+ *                  integer from.
+ */
+#ifndef MBEDTLS_GET_UINT16_BE
+#define MBEDTLS_GET_UINT16_BE( data, offset )                   \
+    (                                                           \
+          ( (uint16_t) ( data )[( offset )    ] << 8 )          \
+        | ( (uint16_t) ( data )[( offset ) + 1]      )          \
+    )
+#endif
+
+/**
+ * Put in memory a 16 bits unsigned integer in big-endian order.
+ *
+ * \param   n       16 bits unsigned integer to put in memory.
+ * \param   data    Base address of the memory where to put the 16
+ *                  bits unsigned integer in.
+ * \param   offset  Offset from \p base where to put the most significant
+ *                  byte of the 16 bits unsigned integer \p n.
+ */
+#ifndef MBEDTLS_PUT_UINT16_BE
+#define MBEDTLS_PUT_UINT16_BE( n, data, offset )                \
+{                                                               \
+    ( data )[( offset )    ] = MBEDTLS_BYTE_1( n );             \
+    ( data )[( offset ) + 1] = MBEDTLS_BYTE_0( n );             \
+}
+#endif
+
+/**
+ * Get the unsigned 64 bits integer corresponding to eight bytes in
+ * big-endian order (MSB first).
+ *
+ * \param   data    Base address of the memory to get the eight bytes from.
+ * \param   offset  Offset from \p base of the first and most significant
+ *                  byte of the eight bytes to build the 64 bits unsigned
+ *                  integer from.
+ */
+#ifndef MBEDTLS_GET_UINT64_BE
+#define MBEDTLS_GET_UINT64_BE( data, offset )                   \
+    (                                                           \
+          ( (uint64_t) ( data )[( offset )    ] << 56 )         \
+        | ( (uint64_t) ( data )[( offset ) + 1] << 48 )         \
+        | ( (uint64_t) ( data )[( offset ) + 2] << 40 )         \
+        | ( (uint64_t) ( data )[( offset ) + 3] << 32 )         \
+        | ( (uint64_t) ( data )[( offset ) + 4] << 24 )         \
+        | ( (uint64_t) ( data )[( offset ) + 5] << 16 )         \
+        | ( (uint64_t) ( data )[( offset ) + 6] <<  8 )         \
+        | ( (uint64_t) ( data )[( offset ) + 7]       )         \
+    )
+#endif
+
+/**
+ * Put in memory a 64 bits unsigned integer in big-endian order.
+ *
+ * \param   n       64 bits unsigned integer to put in memory.
+ * \param   data    Base address of the memory where to put the 64
+ *                  bits unsigned integer in.
+ * \param   offset  Offset from \p base where to put the most significant
+ *                  byte of the 64 bits unsigned integer \p n.
+ */
+#ifndef MBEDTLS_PUT_UINT64_BE
+#define MBEDTLS_PUT_UINT64_BE( n, data, offset )                \
+{                                                               \
+    ( data )[( offset )    ] = MBEDTLS_BYTE_7( n );             \
+    ( data )[( offset ) + 1] = MBEDTLS_BYTE_6( n );             \
+    ( data )[( offset ) + 2] = MBEDTLS_BYTE_5( n );             \
+    ( data )[( offset ) + 3] = MBEDTLS_BYTE_4( n );             \
+    ( data )[( offset ) + 4] = MBEDTLS_BYTE_3( n );             \
+    ( data )[( offset ) + 5] = MBEDTLS_BYTE_2( n );             \
+    ( data )[( offset ) + 6] = MBEDTLS_BYTE_1( n );             \
+    ( data )[( offset ) + 7] = MBEDTLS_BYTE_0( n );             \
+}
+#endif
+
+/**
+ * Get the unsigned 64 bits integer corresponding to eight bytes in
+ * little-endian order (LSB first).
+ *
+ * \param   data    Base address of the memory to get the eight bytes from.
+ * \param   offset  Offset from \p base of the first and least significant
+ *                  byte of the eight bytes to build the 64 bits unsigned
+ *                  integer from.
+ */
+#ifndef MBEDTLS_GET_UINT64_LE
+#define MBEDTLS_GET_UINT64_LE( data, offset )                   \
+    (                                                           \
+          ( (uint64_t) ( data )[( offset ) + 7] << 56 )         \
+        | ( (uint64_t) ( data )[( offset ) + 6] << 48 )         \
+        | ( (uint64_t) ( data )[( offset ) + 5] << 40 )         \
+        | ( (uint64_t) ( data )[( offset ) + 4] << 32 )         \
+        | ( (uint64_t) ( data )[( offset ) + 3] << 24 )         \
+        | ( (uint64_t) ( data )[( offset ) + 2] << 16 )         \
+        | ( (uint64_t) ( data )[( offset ) + 1] <<  8 )         \
+        | ( (uint64_t) ( data )[( offset )    ]       )         \
+    )
+#endif
+
+/**
+ * Put in memory a 64 bits unsigned integer in little-endian order.
+ *
+ * \param   n       64 bits unsigned integer to put in memory.
+ * \param   data    Base address of the memory where to put the 64
+ *                  bits unsigned integer in.
+ * \param   offset  Offset from \p base where to put the least significant
+ *                  byte of the 64 bits unsigned integer \p n.
+ */
+#ifndef MBEDTLS_PUT_UINT64_LE
+#define MBEDTLS_PUT_UINT64_LE( n, data, offset )                \
+{                                                               \
+    ( data )[( offset )    ] = MBEDTLS_BYTE_0( n );             \
+    ( data )[( offset ) + 1] = MBEDTLS_BYTE_1( n );             \
+    ( data )[( offset ) + 2] = MBEDTLS_BYTE_2( n );             \
+    ( data )[( offset ) + 3] = MBEDTLS_BYTE_3( n );             \
+    ( data )[( offset ) + 4] = MBEDTLS_BYTE_4( n );             \
+    ( data )[( offset ) + 5] = MBEDTLS_BYTE_5( n );             \
+    ( data )[( offset ) + 6] = MBEDTLS_BYTE_6( n );             \
+    ( data )[( offset ) + 7] = MBEDTLS_BYTE_7( n );             \
+}
+#endif
+
 #endif /* MBEDTLS_LIBRARY_COMMON_H */
diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index b664fb0..93a7cdc 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -152,11 +152,8 @@
      *     (Total is padded to a multiple of 16-bytes with zeroes)
      */
     p = buf + MBEDTLS_CTR_DRBG_BLOCKSIZE;
-    *p++ = ( data_len >> 24 ) & 0xff;
-    *p++ = ( data_len >> 16 ) & 0xff;
-    *p++ = ( data_len >> 8  ) & 0xff;
-    *p++ = ( data_len       ) & 0xff;
-    p += 3;
+    MBEDTLS_PUT_UINT32_BE( data_len, p, 0);
+    p += 4 + 3;
     *p++ = MBEDTLS_CTR_DRBG_SEEDLEN;
     memcpy( p, data, data_len );
     p[data_len] = 0x80;
diff --git a/library/des.c b/library/des.c
index eddf55e..7f90faa 100644
--- a/library/des.c
+++ b/library/des.c
@@ -44,29 +44,6 @@
 #if !defined(MBEDTLS_DES_ALT)
 
 /*
- * 32-bit integer manipulation macros (big endian)
- */
-#ifndef GET_UINT32_BE
-#define GET_UINT32_BE(n,b,i)                            \
-{                                                       \
-    (n) = ( (uint32_t) (b)[(i)    ] << 24 )             \
-        | ( (uint32_t) (b)[(i) + 1] << 16 )             \
-        | ( (uint32_t) (b)[(i) + 2] <<  8 )             \
-        | ( (uint32_t) (b)[(i) + 3]       );            \
-}
-#endif
-
-#ifndef PUT_UINT32_BE
-#define PUT_UINT32_BE(n,b,i)                            \
-{                                                       \
-    (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
-    (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
-    (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
-    (b)[(i) + 3] = (unsigned char) ( (n)       );       \
-}
-#endif
-
-/*
  * Expanded DES S-boxes
  */
 static const uint32_t SB1[64] =
@@ -423,8 +400,8 @@
     int i;
     uint32_t X, Y, T;
 
-    GET_UINT32_BE( X, key, 0 );
-    GET_UINT32_BE( Y, key, 4 );
+    X = MBEDTLS_GET_UINT32_BE( key, 0 );
+    Y = MBEDTLS_GET_UINT32_BE( key, 4 );
 
     /*
      * Permuted Choice 1
@@ -633,8 +610,8 @@
 
     SK = ctx->sk;
 
-    GET_UINT32_BE( X, input, 0 );
-    GET_UINT32_BE( Y, input, 4 );
+    X = MBEDTLS_GET_UINT32_BE( input, 0 );
+    Y = MBEDTLS_GET_UINT32_BE( input, 4 );
 
     DES_IP( X, Y );
 
@@ -646,8 +623,8 @@
 
     DES_FP( Y, X );
 
-    PUT_UINT32_BE( Y, output, 0 );
-    PUT_UINT32_BE( X, output, 4 );
+    MBEDTLS_PUT_UINT32_BE( Y, output, 0 );
+    MBEDTLS_PUT_UINT32_BE( X, output, 4 );
 
     return( 0 );
 }
@@ -720,8 +697,8 @@
 
     SK = ctx->sk;
 
-    GET_UINT32_BE( X, input, 0 );
-    GET_UINT32_BE( Y, input, 4 );
+    X = MBEDTLS_GET_UINT32_BE( input, 0 );
+    Y = MBEDTLS_GET_UINT32_BE( input, 4 );
 
     DES_IP( X, Y );
 
@@ -745,8 +722,8 @@
 
     DES_FP( Y, X );
 
-    PUT_UINT32_BE( Y, output, 0 );
-    PUT_UINT32_BE( X, output, 4 );
+    MBEDTLS_PUT_UINT32_BE( Y, output, 0 );
+    MBEDTLS_PUT_UINT32_BE( X, output, 4 );
 
     return( 0 );
 }
diff --git a/library/dhm.c b/library/dhm.c
index 29ce755..2ce0ed4 100644
--- a/library/dhm.c
+++ b/library/dhm.c
@@ -270,8 +270,8 @@
         MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( ( X ),               \
                                                    p + 2,               \
                                                    ( n ) ) );           \
-        *p++ = (unsigned char)( ( n ) >> 8 );                           \
-        *p++ = (unsigned char)( ( n )      );                           \
+        *p++ = MBEDTLS_BYTE_1( n );                                     \
+        *p++ = MBEDTLS_BYTE_0( n );                                     \
         p += ( n );                                                     \
     } while( 0 )
 
diff --git a/library/ecjpake.c b/library/ecjpake.c
index d229311..738a977 100644
--- a/library/ecjpake.c
+++ b/library/ecjpake.c
@@ -180,10 +180,7 @@
     if( ret != 0 )
         return( ret );
 
-    (*p)[0] = (unsigned char)( ( len >> 24 ) & 0xFF );
-    (*p)[1] = (unsigned char)( ( len >> 16 ) & 0xFF );
-    (*p)[2] = (unsigned char)( ( len >>  8 ) & 0xFF );
-    (*p)[3] = (unsigned char)( ( len       ) & 0xFF );
+    MBEDTLS_PUT_UINT32_BE( len, *p, 0 );
 
     *p += 4 + len;
 
@@ -223,10 +220,8 @@
     if( end - p < 4 )
         return( MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL );
 
-    *p++ = (unsigned char)( ( id_len >> 24 ) & 0xFF );
-    *p++ = (unsigned char)( ( id_len >> 16 ) & 0xFF );
-    *p++ = (unsigned char)( ( id_len >>  8 ) & 0xFF );
-    *p++ = (unsigned char)( ( id_len       ) & 0xFF );
+    MBEDTLS_PUT_UINT32_BE( id_len, p, 0 );
+    p += 4;
 
     if( end < p || (size_t)( end - p ) < id_len )
         return( MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL );
@@ -366,7 +361,7 @@
         goto cleanup;
     }
 
-    *(*p)++ = (unsigned char)( len & 0xFF );
+    *(*p)++ = MBEDTLS_BYTE_0( len );
     MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &h, *p, len ) ); /* r */
     *p += len;
 
diff --git a/library/ecp.c b/library/ecp.c
index b608ff1..0212069 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -1012,8 +1012,7 @@
     /*
      * Next two bytes are the namedcurve value
      */
-    buf[0] = curve_info->tls_id >> 8;
-    buf[1] = curve_info->tls_id & 0xFF;
+    MBEDTLS_PUT_UINT16_BE( curve_info->tls_id, buf, 0 );
 
     return( 0 );
 }
diff --git a/library/gcm.c b/library/gcm.c
index 835b1b2..910646b 100644
--- a/library/gcm.c
+++ b/library/gcm.c
@@ -59,29 +59,6 @@
     MBEDTLS_INTERNAL_VALIDATE( cond )
 
 /*
- * 32-bit integer manipulation macros (big endian)
- */
-#ifndef GET_UINT32_BE
-#define GET_UINT32_BE(n,b,i)                            \
-{                                                       \
-    (n) = ( (uint32_t) (b)[(i)    ] << 24 )             \
-        | ( (uint32_t) (b)[(i) + 1] << 16 )             \
-        | ( (uint32_t) (b)[(i) + 2] <<  8 )             \
-        | ( (uint32_t) (b)[(i) + 3]       );            \
-}
-#endif
-
-#ifndef PUT_UINT32_BE
-#define PUT_UINT32_BE(n,b,i)                            \
-{                                                       \
-    (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
-    (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
-    (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
-    (b)[(i) + 3] = (unsigned char) ( (n)       );       \
-}
-#endif
-
-/*
  * Initialize a context
  */
 void mbedtls_gcm_init( mbedtls_gcm_context *ctx )
@@ -111,12 +88,12 @@
         return( ret );
 
     /* pack h as two 64-bits ints, big-endian */
-    GET_UINT32_BE( hi, h,  0  );
-    GET_UINT32_BE( lo, h,  4  );
+    hi = MBEDTLS_GET_UINT32_BE( h,  0  );
+    lo = MBEDTLS_GET_UINT32_BE( h,  4  );
     vh = (uint64_t) hi << 32 | lo;
 
-    GET_UINT32_BE( hi, h,  8  );
-    GET_UINT32_BE( lo, h,  12 );
+    hi = MBEDTLS_GET_UINT32_BE( h,  8  );
+    lo = MBEDTLS_GET_UINT32_BE( h,  12 );
     vl = (uint64_t) hi << 32 | lo;
 
     /* 8 = 1000 corresponds to 1 in GF(2^128) */
@@ -223,10 +200,10 @@
     if( mbedtls_aesni_has_support( MBEDTLS_AESNI_CLMUL ) ) {
         unsigned char h[16];
 
-        PUT_UINT32_BE( ctx->HH[8] >> 32, h,  0 );
-        PUT_UINT32_BE( ctx->HH[8],       h,  4 );
-        PUT_UINT32_BE( ctx->HL[8] >> 32, h,  8 );
-        PUT_UINT32_BE( ctx->HL[8],       h, 12 );
+        MBEDTLS_PUT_UINT32_BE( ctx->HH[8] >> 32, h,  0 );
+        MBEDTLS_PUT_UINT32_BE( ctx->HH[8],       h,  4 );
+        MBEDTLS_PUT_UINT32_BE( ctx->HL[8] >> 32, h,  8 );
+        MBEDTLS_PUT_UINT32_BE( ctx->HL[8],       h, 12 );
 
         mbedtls_aesni_gcm_mult( output, x, h );
         return;
@@ -262,10 +239,10 @@
         zl ^= ctx->HL[hi];
     }
 
-    PUT_UINT32_BE( zh >> 32, output, 0 );
-    PUT_UINT32_BE( zh, output, 4 );
-    PUT_UINT32_BE( zl >> 32, output, 8 );
-    PUT_UINT32_BE( zl, output, 12 );
+    MBEDTLS_PUT_UINT32_BE( zh >> 32, output, 0 );
+    MBEDTLS_PUT_UINT32_BE( zh, output, 4 );
+    MBEDTLS_PUT_UINT32_BE( zl >> 32, output, 8 );
+    MBEDTLS_PUT_UINT32_BE( zl, output, 12 );
 }
 
 int mbedtls_gcm_starts( mbedtls_gcm_context *ctx,
@@ -301,7 +278,7 @@
     else
     {
         memset( work_buf, 0x00, 16 );
-        PUT_UINT32_BE( iv_len * 8, work_buf, 12 );
+        MBEDTLS_PUT_UINT32_BE( iv_len * 8, work_buf, 12 );
 
         p = iv;
         while( iv_len > 0 )
@@ -569,10 +546,10 @@
     {
         memset( work_buf, 0x00, 16 );
 
-        PUT_UINT32_BE( ( orig_add_len >> 32 ), work_buf, 0  );
-        PUT_UINT32_BE( ( orig_add_len       ), work_buf, 4  );
-        PUT_UINT32_BE( ( orig_len     >> 32 ), work_buf, 8  );
-        PUT_UINT32_BE( ( orig_len           ), work_buf, 12 );
+        MBEDTLS_PUT_UINT32_BE( ( orig_add_len >> 32 ), work_buf, 0  );
+        MBEDTLS_PUT_UINT32_BE( ( orig_add_len       ), work_buf, 4  );
+        MBEDTLS_PUT_UINT32_BE( ( orig_len     >> 32 ), work_buf, 8  );
+        MBEDTLS_PUT_UINT32_BE( ( orig_len           ), work_buf, 12 );
 
         for( i = 0; i < 16; i++ )
             ctx->buf[i] ^= work_buf[i];
diff --git a/library/md5.c b/library/md5.c
index d7f8cee..a9bbcb4 100644
--- a/library/md5.c
+++ b/library/md5.c
@@ -43,29 +43,6 @@
 
 #if !defined(MBEDTLS_MD5_ALT)
 
-/*
- * 32-bit integer manipulation macros (little endian)
- */
-#ifndef GET_UINT32_LE
-#define GET_UINT32_LE(n,b,i)                            \
-{                                                       \
-    (n) = ( (uint32_t) (b)[(i)    ]       )             \
-        | ( (uint32_t) (b)[(i) + 1] <<  8 )             \
-        | ( (uint32_t) (b)[(i) + 2] << 16 )             \
-        | ( (uint32_t) (b)[(i) + 3] << 24 );            \
-}
-#endif
-
-#ifndef PUT_UINT32_LE
-#define PUT_UINT32_LE(n,b,i)                                    \
-{                                                               \
-    (b)[(i)    ] = (unsigned char) ( ( (n)       ) & 0xFF );    \
-    (b)[(i) + 1] = (unsigned char) ( ( (n) >>  8 ) & 0xFF );    \
-    (b)[(i) + 2] = (unsigned char) ( ( (n) >> 16 ) & 0xFF );    \
-    (b)[(i) + 3] = (unsigned char) ( ( (n) >> 24 ) & 0xFF );    \
-}
-#endif
-
 void mbedtls_md5_init( mbedtls_md5_context *ctx )
 {
     memset( ctx, 0, sizeof( mbedtls_md5_context ) );
@@ -110,22 +87,22 @@
         uint32_t X[16], A, B, C, D;
     } local;
 
-    GET_UINT32_LE( local.X[ 0], data,  0 );
-    GET_UINT32_LE( local.X[ 1], data,  4 );
-    GET_UINT32_LE( local.X[ 2], data,  8 );
-    GET_UINT32_LE( local.X[ 3], data, 12 );
-    GET_UINT32_LE( local.X[ 4], data, 16 );
-    GET_UINT32_LE( local.X[ 5], data, 20 );
-    GET_UINT32_LE( local.X[ 6], data, 24 );
-    GET_UINT32_LE( local.X[ 7], data, 28 );
-    GET_UINT32_LE( local.X[ 8], data, 32 );
-    GET_UINT32_LE( local.X[ 9], data, 36 );
-    GET_UINT32_LE( local.X[10], data, 40 );
-    GET_UINT32_LE( local.X[11], data, 44 );
-    GET_UINT32_LE( local.X[12], data, 48 );
-    GET_UINT32_LE( local.X[13], data, 52 );
-    GET_UINT32_LE( local.X[14], data, 56 );
-    GET_UINT32_LE( local.X[15], data, 60 );
+    local.X[ 0] = MBEDTLS_GET_UINT32_LE( data,  0 );
+    local.X[ 1] = MBEDTLS_GET_UINT32_LE( data,  4 );
+    local.X[ 2] = MBEDTLS_GET_UINT32_LE( data,  8 );
+    local.X[ 3] = MBEDTLS_GET_UINT32_LE( data, 12 );
+    local.X[ 4] = MBEDTLS_GET_UINT32_LE( data, 16 );
+    local.X[ 5] = MBEDTLS_GET_UINT32_LE( data, 20 );
+    local.X[ 6] = MBEDTLS_GET_UINT32_LE( data, 24 );
+    local.X[ 7] = MBEDTLS_GET_UINT32_LE( data, 28 );
+    local.X[ 8] = MBEDTLS_GET_UINT32_LE( data, 32 );
+    local.X[ 9] = MBEDTLS_GET_UINT32_LE( data, 36 );
+    local.X[10] = MBEDTLS_GET_UINT32_LE( data, 40 );
+    local.X[11] = MBEDTLS_GET_UINT32_LE( data, 44 );
+    local.X[12] = MBEDTLS_GET_UINT32_LE( data, 48 );
+    local.X[13] = MBEDTLS_GET_UINT32_LE( data, 52 );
+    local.X[14] = MBEDTLS_GET_UINT32_LE( data, 56 );
+    local.X[15] = MBEDTLS_GET_UINT32_LE( data, 60 );
 
 #define S(x,n)                                                          \
     ( ( (x) << (n) ) | ( ( (x) & 0xFFFFFFFF) >> ( 32 - (n) ) ) )
@@ -330,8 +307,8 @@
          | ( ctx->total[1] <<  3 );
     low  = ( ctx->total[0] <<  3 );
 
-    PUT_UINT32_LE( low,  ctx->buffer, 56 );
-    PUT_UINT32_LE( high, ctx->buffer, 60 );
+    MBEDTLS_PUT_UINT32_LE( low,  ctx->buffer, 56 );
+    MBEDTLS_PUT_UINT32_LE( high, ctx->buffer, 60 );
 
     if( ( ret = mbedtls_internal_md5_process( ctx, ctx->buffer ) ) != 0 )
         return( ret );
@@ -339,10 +316,10 @@
     /*
      * Output final state
      */
-    PUT_UINT32_LE( ctx->state[0], output,  0 );
-    PUT_UINT32_LE( ctx->state[1], output,  4 );
-    PUT_UINT32_LE( ctx->state[2], output,  8 );
-    PUT_UINT32_LE( ctx->state[3], output, 12 );
+    MBEDTLS_PUT_UINT32_LE( ctx->state[0], output,  0 );
+    MBEDTLS_PUT_UINT32_LE( ctx->state[1], output,  4 );
+    MBEDTLS_PUT_UINT32_LE( ctx->state[2], output,  8 );
+    MBEDTLS_PUT_UINT32_LE( ctx->state[3], output, 12 );
 
     return( 0 );
 }
diff --git a/library/nist_kw.c b/library/nist_kw.c
index 5054ca2..e2ab256 100644
--- a/library/nist_kw.c
+++ b/library/nist_kw.c
@@ -77,26 +77,6 @@
 /*! The 32-bit default integrity check value (ICV) for KWP mode. */
 static const  unsigned char NIST_KW_ICV2[] = {0xA6, 0x59, 0x59, 0xA6};
 
-#ifndef GET_UINT32_BE
-#define GET_UINT32_BE(n,b,i)                            \
-do {                                                    \
-    (n) = ( (uint32_t) (b)[(i)    ] << 24 )             \
-        | ( (uint32_t) (b)[(i) + 1] << 16 )             \
-        | ( (uint32_t) (b)[(i) + 2] <<  8 )             \
-        | ( (uint32_t) (b)[(i) + 3]       );            \
-} while( 0 )
-#endif
-
-#ifndef PUT_UINT32_BE
-#define PUT_UINT32_BE(n,b,i)                            \
-do {                                                    \
-    (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
-    (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
-    (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
-    (b)[(i) + 3] = (unsigned char) ( (n)       );       \
-} while( 0 )
-#endif
-
 /*
  * Initialize context
  */
@@ -243,7 +223,7 @@
         }
 
         memcpy( output, NIST_KW_ICV2, KW_SEMIBLOCK_LENGTH / 2 );
-        PUT_UINT32_BE( ( in_len & 0xffffffff ), output,
+        MBEDTLS_PUT_UINT32_BE( ( in_len & 0xffffffff ), output,
                        KW_SEMIBLOCK_LENGTH / 2 );
 
         memcpy( output + KW_SEMIBLOCK_LENGTH, input, in_len );
@@ -474,7 +454,7 @@
             ret = MBEDTLS_ERR_CIPHER_AUTH_FAILED;
         }
 
-        GET_UINT32_BE( Plen, A, KW_SEMIBLOCK_LENGTH / 2 );
+        Plen = MBEDTLS_GET_UINT32_BE( A, KW_SEMIBLOCK_LENGTH / 2 );
 
         /*
          * Plen is the length of the plaintext, when the input is valid.
diff --git a/library/pkcs12.c b/library/pkcs12.c
index 04b1a6d..8f64bc6 100644
--- a/library/pkcs12.c
+++ b/library/pkcs12.c
@@ -285,8 +285,8 @@
         for( i = v; i > 0; i-- )
         {
             j = salt_block[i - 1] + hash_block[i - 1] + c;
-            c = (unsigned char) (j >> 8);
-            salt_block[i - 1] = j & 0xFF;
+            c = MBEDTLS_BYTE_1( j );
+            salt_block[i - 1] = MBEDTLS_BYTE_0( j );
         }
 
         // pwd_block  += B
@@ -294,8 +294,8 @@
         for( i = v; i > 0; i-- )
         {
             j = pwd_block[i - 1] + hash_block[i - 1] + c;
-            c = (unsigned char) (j >> 8);
-            pwd_block[i - 1] = j & 0xFF;
+            c = MBEDTLS_BYTE_1( j );
+            pwd_block[i - 1] = MBEDTLS_BYTE_0( j );
         }
     }
 
diff --git a/library/poly1305.c b/library/poly1305.c
index 492d145..7375a0c 100644
--- a/library/poly1305.c
+++ b/library/poly1305.c
@@ -52,13 +52,6 @@
 
 #define POLY1305_BLOCK_SIZE_BYTES ( 16U )
 
-#define BYTES_TO_U32_LE( data, offset )                           \
-    ( (uint32_t) (data)[offset]                                     \
-          | (uint32_t) ( (uint32_t) (data)[( offset ) + 1] << 8 )   \
-          | (uint32_t) ( (uint32_t) (data)[( offset ) + 2] << 16 )  \
-          | (uint32_t) ( (uint32_t) (data)[( offset ) + 3] << 24 )  \
-    )
-
 /*
  * Our implementation is tuned for 32-bit platforms with a 64-bit multiplier.
  * However we provided an alternative for platforms without such a multiplier.
@@ -129,10 +122,10 @@
     for( i = 0U; i < nblocks; i++ )
     {
         /* The input block is treated as a 128-bit little-endian integer */
-        d0   = BYTES_TO_U32_LE( input, offset + 0  );
-        d1   = BYTES_TO_U32_LE( input, offset + 4  );
-        d2   = BYTES_TO_U32_LE( input, offset + 8  );
-        d3   = BYTES_TO_U32_LE( input, offset + 12 );
+        d0   = MBEDTLS_GET_UINT32_LE( input, offset + 0  );
+        d1   = MBEDTLS_GET_UINT32_LE( input, offset + 4  );
+        d2   = MBEDTLS_GET_UINT32_LE( input, offset + 8  );
+        d3   = MBEDTLS_GET_UINT32_LE( input, offset + 12 );
 
         /* Compute: acc += (padded) block as a 130-bit integer */
         d0  += (uint64_t) acc0;
@@ -257,22 +250,10 @@
     acc3 += ctx->s[3] + (uint32_t) ( d >> 32U );
 
     /* Compute MAC (128 least significant bits of the accumulator) */
-    mac[ 0] = (unsigned char)( acc0       );
-    mac[ 1] = (unsigned char)( acc0 >>  8 );
-    mac[ 2] = (unsigned char)( acc0 >> 16 );
-    mac[ 3] = (unsigned char)( acc0 >> 24 );
-    mac[ 4] = (unsigned char)( acc1       );
-    mac[ 5] = (unsigned char)( acc1 >>  8 );
-    mac[ 6] = (unsigned char)( acc1 >> 16 );
-    mac[ 7] = (unsigned char)( acc1 >> 24 );
-    mac[ 8] = (unsigned char)( acc2       );
-    mac[ 9] = (unsigned char)( acc2 >>  8 );
-    mac[10] = (unsigned char)( acc2 >> 16 );
-    mac[11] = (unsigned char)( acc2 >> 24 );
-    mac[12] = (unsigned char)( acc3       );
-    mac[13] = (unsigned char)( acc3 >>  8 );
-    mac[14] = (unsigned char)( acc3 >> 16 );
-    mac[15] = (unsigned char)( acc3 >> 24 );
+    MBEDTLS_PUT_UINT32_LE( acc0, mac,  0 );
+    MBEDTLS_PUT_UINT32_LE( acc1, mac,  4 );
+    MBEDTLS_PUT_UINT32_LE( acc2, mac,  8 );
+    MBEDTLS_PUT_UINT32_LE( acc3, mac, 12 );
 }
 
 void mbedtls_poly1305_init( mbedtls_poly1305_context *ctx )
@@ -297,15 +278,15 @@
     POLY1305_VALIDATE_RET( key != NULL );
 
     /* r &= 0x0ffffffc0ffffffc0ffffffc0fffffff */
-    ctx->r[0] = BYTES_TO_U32_LE( key, 0 )  & 0x0FFFFFFFU;
-    ctx->r[1] = BYTES_TO_U32_LE( key, 4 )  & 0x0FFFFFFCU;
-    ctx->r[2] = BYTES_TO_U32_LE( key, 8 )  & 0x0FFFFFFCU;
-    ctx->r[3] = BYTES_TO_U32_LE( key, 12 ) & 0x0FFFFFFCU;
+    ctx->r[0] = MBEDTLS_GET_UINT32_LE( key, 0 )  & 0x0FFFFFFFU;
+    ctx->r[1] = MBEDTLS_GET_UINT32_LE( key, 4 )  & 0x0FFFFFFCU;
+    ctx->r[2] = MBEDTLS_GET_UINT32_LE( key, 8 )  & 0x0FFFFFFCU;
+    ctx->r[3] = MBEDTLS_GET_UINT32_LE( key, 12 ) & 0x0FFFFFFCU;
 
-    ctx->s[0] = BYTES_TO_U32_LE( key, 16 );
-    ctx->s[1] = BYTES_TO_U32_LE( key, 20 );
-    ctx->s[2] = BYTES_TO_U32_LE( key, 24 );
-    ctx->s[3] = BYTES_TO_U32_LE( key, 28 );
+    ctx->s[0] = MBEDTLS_GET_UINT32_LE( key, 16 );
+    ctx->s[1] = MBEDTLS_GET_UINT32_LE( key, 20 );
+    ctx->s[2] = MBEDTLS_GET_UINT32_LE( key, 24 );
+    ctx->s[3] = MBEDTLS_GET_UINT32_LE( key, 28 );
 
     /* Initial accumulator state */
     ctx->acc[0] = 0U;
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 3574b98..95aa0d5 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -4506,8 +4506,8 @@
      * uint16 with the value N, and the PSK itself.
      */
 
-    *cur++ = ( data_length >> 8 ) & 0xff;
-    *cur++ = ( data_length >> 0 ) & 0xff;
+    *cur++ = MBEDTLS_BYTE_1( data_length );
+    *cur++ = MBEDTLS_BYTE_0( data_length );
     memset( cur, 0, data_length );
     cur += data_length;
     *cur++ = pms[0];
diff --git a/library/psa_crypto_storage.c b/library/psa_crypto_storage.c
index 09cbab4..c6660b9 100644
--- a/library/psa_crypto_storage.c
+++ b/library/psa_crypto_storage.c
@@ -230,48 +230,6 @@
     return( PSA_SUCCESS );
 }
 
-/*
- * 32-bit integer manipulation macros (little endian)
- */
-#ifndef GET_UINT32_LE
-#define GET_UINT32_LE( n, b, i )                        \
-{                                                       \
-    (n) = ( (uint32_t) (b)[(i)    ]       )             \
-        | ( (uint32_t) (b)[(i) + 1] <<  8 )             \
-        | ( (uint32_t) (b)[(i) + 2] << 16 )             \
-        | ( (uint32_t) (b)[(i) + 3] << 24 );            \
-}
-#endif
-
-#ifndef PUT_UINT32_LE
-#define PUT_UINT32_LE( n, b, i )                                \
-{                                                               \
-    (b)[(i)    ] = (unsigned char) ( ( (n)       ) & 0xFF );    \
-    (b)[(i) + 1] = (unsigned char) ( ( (n) >>  8 ) & 0xFF );    \
-    (b)[(i) + 2] = (unsigned char) ( ( (n) >> 16 ) & 0xFF );    \
-    (b)[(i) + 3] = (unsigned char) ( ( (n) >> 24 ) & 0xFF );    \
-}
-#endif
-
-/*
- * 16-bit integer manipulation macros (little endian)
- */
-#ifndef GET_UINT16_LE
-#define GET_UINT16_LE( n, b, i )                        \
-{                                                       \
-    (n) = ( (uint16_t) (b)[(i)    ]       )             \
-        | ( (uint16_t) (b)[(i) + 1] <<  8 );            \
-}
-#endif
-
-#ifndef PUT_UINT16_LE
-#define PUT_UINT16_LE( n, b, i )                                \
-{                                                               \
-    (b)[(i)    ] = (unsigned char) ( ( (n)       ) & 0xFF );    \
-    (b)[(i) + 1] = (unsigned char) ( ( (n) >>  8 ) & 0xFF );    \
-}
-#endif
-
 /**
  * Persistent key storage magic header.
  */
@@ -298,14 +256,14 @@
         (psa_persistent_key_storage_format *) storage_data;
 
     memcpy( storage_format->magic, PSA_KEY_STORAGE_MAGIC_HEADER, PSA_KEY_STORAGE_MAGIC_HEADER_LENGTH );
-    PUT_UINT32_LE( 0, storage_format->version, 0 );
-    PUT_UINT32_LE( attr->lifetime, storage_format->lifetime, 0 );
-    PUT_UINT16_LE( (uint16_t) attr->type, storage_format->type, 0 );
-    PUT_UINT16_LE( (uint16_t) attr->bits, storage_format->bits, 0 );
-    PUT_UINT32_LE( attr->policy.usage, storage_format->policy, 0 );
-    PUT_UINT32_LE( attr->policy.alg, storage_format->policy, sizeof( uint32_t ) );
-    PUT_UINT32_LE( attr->policy.alg2, storage_format->policy, 2 * sizeof( uint32_t ) );
-    PUT_UINT32_LE( data_length, storage_format->data_len, 0 );
+    MBEDTLS_PUT_UINT32_LE( 0, storage_format->version, 0 );
+    MBEDTLS_PUT_UINT32_LE( attr->lifetime, storage_format->lifetime, 0 );
+    MBEDTLS_PUT_UINT16_LE( (uint16_t) attr->type, storage_format->type, 0 );
+    MBEDTLS_PUT_UINT16_LE( (uint16_t) attr->bits, storage_format->bits, 0 );
+    MBEDTLS_PUT_UINT32_LE( attr->policy.usage, storage_format->policy, 0 );
+    MBEDTLS_PUT_UINT32_LE( attr->policy.alg, storage_format->policy, sizeof( uint32_t ) );
+    MBEDTLS_PUT_UINT32_LE( attr->policy.alg2, storage_format->policy, 2 * sizeof( uint32_t ) );
+    MBEDTLS_PUT_UINT32_LE( data_length, storage_format->data_len, 0 );
     memcpy( storage_format->key_data, data, data_length );
 }
 
@@ -335,11 +293,11 @@
     if( status != PSA_SUCCESS )
         return( status );
 
-    GET_UINT32_LE( version, storage_format->version, 0 );
+    version = MBEDTLS_GET_UINT32_LE( storage_format->version, 0 );
     if( version != 0 )
         return( PSA_ERROR_DATA_INVALID );
 
-    GET_UINT32_LE( *key_data_length, storage_format->data_len, 0 );
+    *key_data_length = MBEDTLS_GET_UINT32_LE( storage_format->data_len, 0 );
     if( *key_data_length > ( storage_data_length - sizeof(*storage_format) ) ||
         *key_data_length > PSA_CRYPTO_MAX_STORAGE_SIZE )
         return( PSA_ERROR_DATA_INVALID );
@@ -356,12 +314,12 @@
         memcpy( *key_data, storage_format->key_data, *key_data_length );
     }
 
-    GET_UINT32_LE( attr->lifetime, storage_format->lifetime, 0 );
-    GET_UINT16_LE( attr->type, storage_format->type, 0 );
-    GET_UINT16_LE( attr->bits, storage_format->bits, 0 );
-    GET_UINT32_LE( attr->policy.usage, storage_format->policy, 0 );
-    GET_UINT32_LE( attr->policy.alg, storage_format->policy, sizeof( uint32_t ) );
-    GET_UINT32_LE( attr->policy.alg2, storage_format->policy, 2 * sizeof( uint32_t ) );
+    attr->lifetime = MBEDTLS_GET_UINT32_LE( storage_format->lifetime, 0 );
+    attr->type = MBEDTLS_GET_UINT16_LE( storage_format->type, 0 );
+    attr->bits = MBEDTLS_GET_UINT16_LE( storage_format->bits, 0 );
+    attr->policy.usage = MBEDTLS_GET_UINT32_LE( storage_format->policy, 0 );
+    attr->policy.alg = MBEDTLS_GET_UINT32_LE( storage_format->policy, sizeof( uint32_t ) );
+    attr->policy.alg2 = MBEDTLS_GET_UINT32_LE( storage_format->policy, 2 * sizeof( uint32_t ) );
 
     return( PSA_SUCCESS );
 }
diff --git a/library/psa_its_file.c b/library/psa_its_file.c
index 492be1c..c4782cd 100644
--- a/library/psa_its_file.c
+++ b/library/psa_its_file.c
@@ -191,14 +191,8 @@
     size_t n;
 
     memcpy( header.magic, PSA_ITS_MAGIC_STRING, PSA_ITS_MAGIC_LENGTH );
-    header.size[0] = data_length & 0xff;
-    header.size[1] = ( data_length >> 8 ) & 0xff;
-    header.size[2] = ( data_length >> 16 ) & 0xff;
-    header.size[3] = ( data_length >> 24 ) & 0xff;
-    header.flags[0] = create_flags & 0xff;
-    header.flags[1] = ( create_flags >> 8 ) & 0xff;
-    header.flags[2] = ( create_flags >> 16 ) & 0xff;
-    header.flags[3] = ( create_flags >> 24 ) & 0xff;
+    MBEDTLS_PUT_UINT32_LE( data_length, header.size, 0 );
+    MBEDTLS_PUT_UINT32_LE( create_flags, header.flags, 0 );
 
     psa_its_fill_filename( uid, filename );
     stream = fopen( PSA_ITS_STORAGE_TEMP, "wb" );
diff --git a/library/ripemd160.c b/library/ripemd160.c
index d2ccbbe..41d8387 100644
--- a/library/ripemd160.c
+++ b/library/ripemd160.c
@@ -44,29 +44,6 @@
 
 #if !defined(MBEDTLS_RIPEMD160_ALT)
 
-/*
- * 32-bit integer manipulation macros (little endian)
- */
-#ifndef GET_UINT32_LE
-#define GET_UINT32_LE(n,b,i)                            \
-{                                                       \
-    (n) = ( (uint32_t) (b)[(i)    ]       )             \
-        | ( (uint32_t) (b)[(i) + 1] <<  8 )             \
-        | ( (uint32_t) (b)[(i) + 2] << 16 )             \
-        | ( (uint32_t) (b)[(i) + 3] << 24 );            \
-}
-#endif
-
-#ifndef PUT_UINT32_LE
-#define PUT_UINT32_LE(n,b,i)                                    \
-{                                                               \
-    (b)[(i)    ] = (unsigned char) ( ( (n)       ) & 0xFF );    \
-    (b)[(i) + 1] = (unsigned char) ( ( (n) >>  8 ) & 0xFF );    \
-    (b)[(i) + 2] = (unsigned char) ( ( (n) >> 16 ) & 0xFF );    \
-    (b)[(i) + 3] = (unsigned char) ( ( (n) >> 24 ) & 0xFF );    \
-}
-#endif
-
 void mbedtls_ripemd160_init( mbedtls_ripemd160_context *ctx )
 {
     memset( ctx, 0, sizeof( mbedtls_ripemd160_context ) );
@@ -115,22 +92,22 @@
         uint32_t A, B, C, D, E, Ap, Bp, Cp, Dp, Ep, X[16];
     } local;
 
-    GET_UINT32_LE( local.X[ 0], data,  0 );
-    GET_UINT32_LE( local.X[ 1], data,  4 );
-    GET_UINT32_LE( local.X[ 2], data,  8 );
-    GET_UINT32_LE( local.X[ 3], data, 12 );
-    GET_UINT32_LE( local.X[ 4], data, 16 );
-    GET_UINT32_LE( local.X[ 5], data, 20 );
-    GET_UINT32_LE( local.X[ 6], data, 24 );
-    GET_UINT32_LE( local.X[ 7], data, 28 );
-    GET_UINT32_LE( local.X[ 8], data, 32 );
-    GET_UINT32_LE( local.X[ 9], data, 36 );
-    GET_UINT32_LE( local.X[10], data, 40 );
-    GET_UINT32_LE( local.X[11], data, 44 );
-    GET_UINT32_LE( local.X[12], data, 48 );
-    GET_UINT32_LE( local.X[13], data, 52 );
-    GET_UINT32_LE( local.X[14], data, 56 );
-    GET_UINT32_LE( local.X[15], data, 60 );
+    local.X[ 0] = MBEDTLS_GET_UINT32_LE( data,  0 );
+    local.X[ 1] = MBEDTLS_GET_UINT32_LE( data,  4 );
+    local.X[ 2] = MBEDTLS_GET_UINT32_LE( data,  8 );
+    local.X[ 3] = MBEDTLS_GET_UINT32_LE( data, 12 );
+    local.X[ 4] = MBEDTLS_GET_UINT32_LE( data, 16 );
+    local.X[ 5] = MBEDTLS_GET_UINT32_LE( data, 20 );
+    local.X[ 6] = MBEDTLS_GET_UINT32_LE( data, 24 );
+    local.X[ 7] = MBEDTLS_GET_UINT32_LE( data, 28 );
+    local.X[ 8] = MBEDTLS_GET_UINT32_LE( data, 32 );
+    local.X[ 9] = MBEDTLS_GET_UINT32_LE( data, 36 );
+    local.X[10] = MBEDTLS_GET_UINT32_LE( data, 40 );
+    local.X[11] = MBEDTLS_GET_UINT32_LE( data, 44 );
+    local.X[12] = MBEDTLS_GET_UINT32_LE( data, 48 );
+    local.X[13] = MBEDTLS_GET_UINT32_LE( data, 52 );
+    local.X[14] = MBEDTLS_GET_UINT32_LE( data, 56 );
+    local.X[15] = MBEDTLS_GET_UINT32_LE( data, 60 );
 
     local.A = local.Ap = ctx->state[0];
     local.B = local.Bp = ctx->state[1];
@@ -377,8 +354,8 @@
          | ( ctx->total[1] <<  3 );
     low  = ( ctx->total[0] <<  3 );
 
-    PUT_UINT32_LE( low,  msglen, 0 );
-    PUT_UINT32_LE( high, msglen, 4 );
+    MBEDTLS_PUT_UINT32_LE( low,  msglen, 0 );
+    MBEDTLS_PUT_UINT32_LE( high, msglen, 4 );
 
     last = ctx->total[0] & 0x3F;
     padn = ( last < 56 ) ? ( 56 - last ) : ( 120 - last );
@@ -391,11 +368,11 @@
     if( ret != 0 )
         return( ret );
 
-    PUT_UINT32_LE( ctx->state[0], output,  0 );
-    PUT_UINT32_LE( ctx->state[1], output,  4 );
-    PUT_UINT32_LE( ctx->state[2], output,  8 );
-    PUT_UINT32_LE( ctx->state[3], output, 12 );
-    PUT_UINT32_LE( ctx->state[4], output, 16 );
+    MBEDTLS_PUT_UINT32_LE( ctx->state[0], output,  0 );
+    MBEDTLS_PUT_UINT32_LE( ctx->state[1], output,  4 );
+    MBEDTLS_PUT_UINT32_LE( ctx->state[2], output,  8 );
+    MBEDTLS_PUT_UINT32_LE( ctx->state[3], output, 12 );
+    MBEDTLS_PUT_UINT32_LE( ctx->state[4], output, 16 );
 
     return( 0 );
 }
diff --git a/library/sha1.c b/library/sha1.c
index 545d093..6fc9371 100644
--- a/library/sha1.c
+++ b/library/sha1.c
@@ -48,29 +48,6 @@
 
 #if !defined(MBEDTLS_SHA1_ALT)
 
-/*
- * 32-bit integer manipulation macros (big endian)
- */
-#ifndef GET_UINT32_BE
-#define GET_UINT32_BE(n,b,i)                            \
-{                                                       \
-    (n) = ( (uint32_t) (b)[(i)    ] << 24 )             \
-        | ( (uint32_t) (b)[(i) + 1] << 16 )             \
-        | ( (uint32_t) (b)[(i) + 2] <<  8 )             \
-        | ( (uint32_t) (b)[(i) + 3]       );            \
-}
-#endif
-
-#ifndef PUT_UINT32_BE
-#define PUT_UINT32_BE(n,b,i)                            \
-{                                                       \
-    (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
-    (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
-    (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
-    (b)[(i) + 3] = (unsigned char) ( (n)       );       \
-}
-#endif
-
 void mbedtls_sha1_init( mbedtls_sha1_context *ctx )
 {
     SHA1_VALIDATE( ctx != NULL );
@@ -126,22 +103,22 @@
     SHA1_VALIDATE_RET( ctx != NULL );
     SHA1_VALIDATE_RET( (const unsigned char *)data != NULL );
 
-    GET_UINT32_BE( local.W[ 0], data,  0 );
-    GET_UINT32_BE( local.W[ 1], data,  4 );
-    GET_UINT32_BE( local.W[ 2], data,  8 );
-    GET_UINT32_BE( local.W[ 3], data, 12 );
-    GET_UINT32_BE( local.W[ 4], data, 16 );
-    GET_UINT32_BE( local.W[ 5], data, 20 );
-    GET_UINT32_BE( local.W[ 6], data, 24 );
-    GET_UINT32_BE( local.W[ 7], data, 28 );
-    GET_UINT32_BE( local.W[ 8], data, 32 );
-    GET_UINT32_BE( local.W[ 9], data, 36 );
-    GET_UINT32_BE( local.W[10], data, 40 );
-    GET_UINT32_BE( local.W[11], data, 44 );
-    GET_UINT32_BE( local.W[12], data, 48 );
-    GET_UINT32_BE( local.W[13], data, 52 );
-    GET_UINT32_BE( local.W[14], data, 56 );
-    GET_UINT32_BE( local.W[15], data, 60 );
+    local.W[ 0] = MBEDTLS_GET_UINT32_BE( data,  0 );
+    local.W[ 1] = MBEDTLS_GET_UINT32_BE( data,  4 );
+    local.W[ 2] = MBEDTLS_GET_UINT32_BE( data,  8 );
+    local.W[ 3] = MBEDTLS_GET_UINT32_BE( data, 12 );
+    local.W[ 4] = MBEDTLS_GET_UINT32_BE( data, 16 );
+    local.W[ 5] = MBEDTLS_GET_UINT32_BE( data, 20 );
+    local.W[ 6] = MBEDTLS_GET_UINT32_BE( data, 24 );
+    local.W[ 7] = MBEDTLS_GET_UINT32_BE( data, 28 );
+    local.W[ 8] = MBEDTLS_GET_UINT32_BE( data, 32 );
+    local.W[ 9] = MBEDTLS_GET_UINT32_BE( data, 36 );
+    local.W[10] = MBEDTLS_GET_UINT32_BE( data, 40 );
+    local.W[11] = MBEDTLS_GET_UINT32_BE( data, 44 );
+    local.W[12] = MBEDTLS_GET_UINT32_BE( data, 48 );
+    local.W[13] = MBEDTLS_GET_UINT32_BE( data, 52 );
+    local.W[14] = MBEDTLS_GET_UINT32_BE( data, 56 );
+    local.W[15] = MBEDTLS_GET_UINT32_BE( data, 60 );
 
 #define S(x,n) (((x) << (n)) | (((x) & 0xFFFFFFFF) >> (32 - (n))))
 
@@ -385,8 +362,8 @@
          | ( ctx->total[1] <<  3 );
     low  = ( ctx->total[0] <<  3 );
 
-    PUT_UINT32_BE( high, ctx->buffer, 56 );
-    PUT_UINT32_BE( low,  ctx->buffer, 60 );
+    MBEDTLS_PUT_UINT32_BE( high, ctx->buffer, 56 );
+    MBEDTLS_PUT_UINT32_BE( low,  ctx->buffer, 60 );
 
     if( ( ret = mbedtls_internal_sha1_process( ctx, ctx->buffer ) ) != 0 )
         return( ret );
@@ -394,11 +371,11 @@
     /*
      * Output final state
      */
-    PUT_UINT32_BE( ctx->state[0], output,  0 );
-    PUT_UINT32_BE( ctx->state[1], output,  4 );
-    PUT_UINT32_BE( ctx->state[2], output,  8 );
-    PUT_UINT32_BE( ctx->state[3], output, 12 );
-    PUT_UINT32_BE( ctx->state[4], output, 16 );
+    MBEDTLS_PUT_UINT32_BE( ctx->state[0], output,  0 );
+    MBEDTLS_PUT_UINT32_BE( ctx->state[1], output,  4 );
+    MBEDTLS_PUT_UINT32_BE( ctx->state[2], output,  8 );
+    MBEDTLS_PUT_UINT32_BE( ctx->state[3], output, 12 );
+    MBEDTLS_PUT_UINT32_BE( ctx->state[4], output, 16 );
 
     return( 0 );
 }
diff --git a/library/sha256.c b/library/sha256.c
index 6ec6da2..c3573f8 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -50,29 +50,6 @@
 
 #if !defined(MBEDTLS_SHA256_ALT)
 
-/*
- * 32-bit integer manipulation macros (big endian)
- */
-#ifndef GET_UINT32_BE
-#define GET_UINT32_BE(n,b,i)                            \
-do {                                                    \
-    (n) = ( (uint32_t) (b)[(i)    ] << 24 )             \
-        | ( (uint32_t) (b)[(i) + 1] << 16 )             \
-        | ( (uint32_t) (b)[(i) + 2] <<  8 )             \
-        | ( (uint32_t) (b)[(i) + 3]       );            \
-} while( 0 )
-#endif
-
-#ifndef PUT_UINT32_BE
-#define PUT_UINT32_BE(n,b,i)                            \
-do {                                                    \
-    (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
-    (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
-    (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
-    (b)[(i) + 3] = (unsigned char) ( (n)       );       \
-} while( 0 )
-#endif
-
 void mbedtls_sha256_init( mbedtls_sha256_context *ctx )
 {
     SHA256_VALIDATE( ctx != NULL );
@@ -213,7 +190,7 @@
     for( i = 0; i < 64; i++ )
     {
         if( i < 16 )
-            GET_UINT32_BE( local.W[i], data, 4 * i );
+            local.W[i] = MBEDTLS_GET_UINT32_BE( data, 4 * i );
         else
             R( i );
 
@@ -228,7 +205,7 @@
     }
 #else /* MBEDTLS_SHA256_SMALLER */
     for( i = 0; i < 16; i++ )
-        GET_UINT32_BE( local.W[i], data, 4 * i );
+        local.W[i] = MBEDTLS_GET_UINT32_BE( data, 4 * i );
 
     for( i = 0; i < 16; i += 8 )
     {
@@ -378,8 +355,8 @@
          | ( ctx->total[1] <<  3 );
     low  = ( ctx->total[0] <<  3 );
 
-    PUT_UINT32_BE( high, ctx->buffer, 56 );
-    PUT_UINT32_BE( low,  ctx->buffer, 60 );
+    MBEDTLS_PUT_UINT32_BE( high, ctx->buffer, 56 );
+    MBEDTLS_PUT_UINT32_BE( low,  ctx->buffer, 60 );
 
     if( ( ret = mbedtls_internal_sha256_process( ctx, ctx->buffer ) ) != 0 )
         return( ret );
@@ -387,18 +364,18 @@
     /*
      * Output final state
      */
-    PUT_UINT32_BE( ctx->state[0], output,  0 );
-    PUT_UINT32_BE( ctx->state[1], output,  4 );
-    PUT_UINT32_BE( ctx->state[2], output,  8 );
-    PUT_UINT32_BE( ctx->state[3], output, 12 );
-    PUT_UINT32_BE( ctx->state[4], output, 16 );
-    PUT_UINT32_BE( ctx->state[5], output, 20 );
-    PUT_UINT32_BE( ctx->state[6], output, 24 );
+    MBEDTLS_PUT_UINT32_BE( ctx->state[0], output,  0 );
+    MBEDTLS_PUT_UINT32_BE( ctx->state[1], output,  4 );
+    MBEDTLS_PUT_UINT32_BE( ctx->state[2], output,  8 );
+    MBEDTLS_PUT_UINT32_BE( ctx->state[3], output, 12 );
+    MBEDTLS_PUT_UINT32_BE( ctx->state[4], output, 16 );
+    MBEDTLS_PUT_UINT32_BE( ctx->state[5], output, 20 );
+    MBEDTLS_PUT_UINT32_BE( ctx->state[6], output, 24 );
 
 #if defined(MBEDTLS_SHA224_C)
     if( ctx->is224 == 0 )
 #endif
-        PUT_UINT32_BE( ctx->state[7], output, 28 );
+        MBEDTLS_PUT_UINT32_BE( ctx->state[7], output, 28 );
 
     return( 0 );
 }
diff --git a/library/sha512.c b/library/sha512.c
index 6511c6e..2b4cc54 100644
--- a/library/sha512.c
+++ b/library/sha512.c
@@ -56,44 +56,13 @@
 
 #if !defined(MBEDTLS_SHA512_ALT)
 
-/*
- * 64-bit integer manipulation macros (big endian)
- */
-#ifndef GET_UINT64_BE
-#define GET_UINT64_BE(n,b,i)                            \
-{                                                       \
-    (n) = ( (uint64_t) (b)[(i)    ] << 56 )       \
-        | ( (uint64_t) (b)[(i) + 1] << 48 )       \
-        | ( (uint64_t) (b)[(i) + 2] << 40 )       \
-        | ( (uint64_t) (b)[(i) + 3] << 32 )       \
-        | ( (uint64_t) (b)[(i) + 4] << 24 )       \
-        | ( (uint64_t) (b)[(i) + 5] << 16 )       \
-        | ( (uint64_t) (b)[(i) + 6] <<  8 )       \
-        | ( (uint64_t) (b)[(i) + 7]       );      \
-}
-#endif /* GET_UINT64_BE */
-
-#ifndef PUT_UINT64_BE
-#define PUT_UINT64_BE(n,b,i)                            \
-{                                                       \
-    (b)[(i)    ] = (unsigned char) ( (n) >> 56 );       \
-    (b)[(i) + 1] = (unsigned char) ( (n) >> 48 );       \
-    (b)[(i) + 2] = (unsigned char) ( (n) >> 40 );       \
-    (b)[(i) + 3] = (unsigned char) ( (n) >> 32 );       \
-    (b)[(i) + 4] = (unsigned char) ( (n) >> 24 );       \
-    (b)[(i) + 5] = (unsigned char) ( (n) >> 16 );       \
-    (b)[(i) + 6] = (unsigned char) ( (n) >>  8 );       \
-    (b)[(i) + 7] = (unsigned char) ( (n)       );       \
-}
-#endif /* PUT_UINT64_BE */
-
 #if defined(MBEDTLS_SHA512_SMALLER)
 static void sha512_put_uint64_be( uint64_t n, unsigned char *b, uint8_t i )
 {
-    PUT_UINT64_BE(n, b, i);
+    MBEDTLS_PUT_UINT64_BE(n, b, i);
 }
 #else
-#define sha512_put_uint64_be    PUT_UINT64_BE
+#define sha512_put_uint64_be    MBEDTLS_PUT_UINT64_BE
 #endif /* MBEDTLS_SHA512_SMALLER */
 
 void mbedtls_sha512_init( mbedtls_sha512_context *ctx )
@@ -261,7 +230,7 @@
     {
         if( i < 16 )
         {
-            GET_UINT64_BE( local.W[i], data, i << 3 );
+            local.W[i] = MBEDTLS_GET_UINT64_BE( data, i << 3 );
         }
         else
         {
@@ -281,7 +250,7 @@
 #else /* MBEDTLS_SHA512_SMALLER */
     for( i = 0; i < 16; i++ )
     {
-        GET_UINT64_BE( local.W[i], data, i << 3 );
+        local.W[i] = MBEDTLS_GET_UINT64_BE( data, i << 3 );
     }
 
     for( ; i < 80; i++ )
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index e0a1c24..9120aa2 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -136,18 +136,19 @@
      * } ServerNameList;
      *
      */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SERVERNAME, p, 0 );
+    p += 2;
 
-    *p++ = (unsigned char)( ( (hostname_len + 5) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( (hostname_len + 5)      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( hostname_len + 5, p, 0 );
+    p += 2;
 
-    *p++ = (unsigned char)( ( (hostname_len + 3) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( (hostname_len + 3)      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( hostname_len + 3, p, 0 );
+    p += 2;
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME_HOSTNAME ) & 0xFF );
-    *p++ = (unsigned char)( ( hostname_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( hostname_len      ) & 0xFF );
+    *p++ = MBEDTLS_BYTE_0( MBEDTLS_TLS_EXT_SERVERNAME_HOSTNAME );
+
+    MBEDTLS_PUT_UINT16_BE( hostname_len, p, 0 );
+    p += 2;
 
     memcpy( p, ssl->hostname, hostname_len );
 
@@ -181,14 +182,12 @@
     /*
      * Secure renegotiation
      */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO      )
-                            & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO, p, 0 );
+    p += 2;
 
     *p++ = 0x00;
-    *p++ = ( ssl->verify_data_len + 1 ) & 0xFF;
-    *p++ = ssl->verify_data_len & 0xFF;
+    *p++ = MBEDTLS_BYTE_0( ssl->verify_data_len + 1 );
+    *p++ = MBEDTLS_BYTE_0( ssl->verify_data_len );
 
     memcpy( p, ssl->own_verify_data, ssl->verify_data_len );
 
@@ -283,14 +282,14 @@
      * SignatureAndHashAlgorithm
      *   supported_signature_algorithms<2..2^16-2>;
      */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SIG_ALG >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SIG_ALG      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SIG_ALG, p, 0 );
+    p += 2;
 
-    *p++ = (unsigned char)( ( ( sig_alg_len + 2 ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ( sig_alg_len + 2 )      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( sig_alg_len + 2, p, 0 );
+    p += 2;
 
-    *p++ = (unsigned char)( ( sig_alg_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( sig_alg_len      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( sig_alg_len, p, 0 );
+    p += 2;
 
     *olen = 6 + sig_alg_len;
 
@@ -354,20 +353,18 @@
          grp_id++ )
     {
         info = mbedtls_ecp_curve_info_from_grp_id( *grp_id );
-        elliptic_curve_list[elliptic_curve_len++] = info->tls_id >> 8;
-        elliptic_curve_list[elliptic_curve_len++] = info->tls_id & 0xFF;
+        elliptic_curve_list[elliptic_curve_len++] = MBEDTLS_BYTE_1( info->tls_id );
+        elliptic_curve_list[elliptic_curve_len++] = MBEDTLS_BYTE_0( info->tls_id );
     }
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES      )
-                            & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES, p, 0 );
+    p += 2;
 
-    *p++ = (unsigned char)( ( ( elliptic_curve_len + 2 ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ( elliptic_curve_len + 2 )      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( elliptic_curve_len + 2, p, 0 );
+    p += 2;
 
-    *p++ = (unsigned char)( ( ( elliptic_curve_len     ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ( elliptic_curve_len     )      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( elliptic_curve_len, p, 0 );
+    p += 2;
 
     *olen = 6 + elliptic_curve_len;
 
@@ -388,10 +385,8 @@
         ( "client hello, adding supported_point_formats extension" ) );
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS      )
-                            & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS, p, 0 );
+    p += 2;
 
     *p++ = 0x00;
     *p++ = 2;
@@ -427,8 +422,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ECJPAKE_KKPP >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ECJPAKE_KKPP      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_ECJPAKE_KKPP, p, 0 );
+    p += 2;
 
     /*
      * We may need to send ClientHello multiple times for Hello verification.
@@ -470,8 +465,8 @@
         memcpy( p + 2, ssl->handshake->ecjpake_cache, kkpp_len );
     }
 
-    *p++ = (unsigned char)( ( kkpp_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( kkpp_len      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( kkpp_len, p, 0 );
+    p += 2;
 
     *olen = kkpp_len + 4;
 
@@ -510,11 +505,11 @@
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, (unsigned)( ssl->own_cid_len + 5 ) );
 
     /* Add extension ID + size */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_CID, p, 0 );
+    p += 2;
     ext_len = (size_t) ssl->own_cid_len + 1;
-    *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( ext_len, p, 0 );
+    p += 2;
 
     *p++ = (uint8_t) ssl->own_cid_len;
     memcpy( p, ssl->own_cid, ssl->own_cid_len );
@@ -543,10 +538,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 5 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH      )
-                            & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH, p, 0 );
+    p += 2;
 
     *p++ = 0x00;
     *p++ = 1;
@@ -577,8 +570,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC, p, 0 );
+    p += 2;
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -607,10 +600,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET      )
-                            & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET, p, 0 );
+    p += 2;
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -641,11 +632,11 @@
     /* The addition is safe here since the ticket length is 16 bit. */
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 + tlen );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SESSION_TICKET, p, 0 );
+    p += 2;
 
-    *p++ = (unsigned char)( ( tlen >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( tlen      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( tlen, p, 0 );
+    p += 2;
 
     *olen = 4;
 
@@ -685,8 +676,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 + alpnlen );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_ALPN, p, 0 );
+    p += 2;
 
     /*
      * opaque ProtocolName<1..2^8-1>;
@@ -713,12 +704,10 @@
     *olen = p - buf;
 
     /* List length = olen - 2 (ext_type) - 2 (ext_len) - 2 (list_len) */
-    buf[4] = (unsigned char)( ( ( *olen - 6 ) >> 8 ) & 0xFF );
-    buf[5] = (unsigned char)( ( ( *olen - 6 )      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( *olen - 6, buf, 4 );
 
     /* Extension length = olen - 2 (ext_type) - 2 (ext_len) */
-    buf[2] = (unsigned char)( ( ( *olen - 4 ) >> 8 ) & 0xFF );
-    buf[3] = (unsigned char)( ( ( *olen - 4 )      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( *olen - 4, buf, 2 );
 
     return( 0 );
 }
@@ -770,12 +759,11 @@
      */
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, ext_len + 4 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_USE_SRTP, p, 0 );
+    p += 2;
 
-
-    *p++ = (unsigned char)( ( ( ext_len & 0xFF00 ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ext_len & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( ext_len, p, 0 );
+    p += 2;
 
     /* protection profile length: 2*(ssl->conf->dtls_srtp_profile_list_len) */
     /* micro-optimization:
@@ -786,8 +774,7 @@
      *                        >> 8 ) & 0xFF );
      */
     *p++ = 0;
-    *p++ = (unsigned char)( ( 2 * ssl->conf->dtls_srtp_profile_list_len )
-                            & 0xFF );
+    *p++ = MBEDTLS_BYTE_0( 2 * ssl->conf->dtls_srtp_profile_list_len );
 
     for( protection_profiles_index=0;
          protection_profiles_index < ssl->conf->dtls_srtp_profile_list_len;
@@ -799,8 +786,8 @@
         {
             MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_write_use_srtp_ext, add profile: %04x",
                                         profile_value ) );
-            *p++ = ( ( profile_value >> 8 ) & 0xFF );
-            *p++ = ( profile_value & 0xFF );
+            MBEDTLS_PUT_UINT16_BE( profile_value, p, 0 );
+            p += 2;
         }
         else
         {
@@ -868,10 +855,8 @@
 
 #if defined(MBEDTLS_HAVE_TIME)
     t = mbedtls_time( NULL );
-    *p++ = (unsigned char)( t >> 24 );
-    *p++ = (unsigned char)( t >> 16 );
-    *p++ = (unsigned char)( t >>  8 );
-    *p++ = (unsigned char)( t       );
+    MBEDTLS_PUT_UINT32_BE( t, p, 0 );
+    p += 4;
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, current time: %" MBEDTLS_PRINTF_LONGLONG,
                                 (long long) t ) );
@@ -1154,8 +1139,8 @@
         MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
 
         n++;
-        *p++ = (unsigned char)( ciphersuites[i] >> 8 );
-        *p++ = (unsigned char)( ciphersuites[i]      );
+        MBEDTLS_PUT_UINT16_BE( ciphersuites[i], p, 0 );
+        p += 2;
     }
 
     MBEDTLS_SSL_DEBUG_MSG( 3,
@@ -1170,8 +1155,8 @@
     {
         MBEDTLS_SSL_DEBUG_MSG( 3, ( "adding EMPTY_RENEGOTIATION_INFO_SCSV" ) );
         MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
-        *p++ = (unsigned char)( MBEDTLS_SSL_EMPTY_RENEGOTIATION_INFO >> 8 );
-        *p++ = (unsigned char)( MBEDTLS_SSL_EMPTY_RENEGOTIATION_INFO      );
+        MBEDTLS_PUT_UINT16_BE( MBEDTLS_SSL_EMPTY_RENEGOTIATION_INFO, p, 0 );
+        p += 2;
         n++;
     }
 
@@ -1334,9 +1319,8 @@
     {
         /* No need to check for space here, because the extension
          * writing functions already took care of that. */
-        *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
-        p += ext_len;
+        MBEDTLS_PUT_UINT16_BE( ext_len, p, 0 );
+        p += 2 + ext_len;
     }
 
     ssl->out_msglen  = p - buf;
@@ -2756,8 +2740,7 @@
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
     if( len_bytes == 2 )
     {
-        ssl->out_msg[offset+0] = (unsigned char)( *olen >> 8 );
-        ssl->out_msg[offset+1] = (unsigned char)( *olen      );
+        MBEDTLS_PUT_UINT16_BE( *olen, ssl->out_msg, offset );
         *olen += 2;
     }
 #endif
@@ -3514,8 +3497,7 @@
          */
         content_len = mbedtls_dhm_get_len( &ssl->handshake->dhm_ctx );
 
-        ssl->out_msg[4] = (unsigned char)( content_len >> 8 );
-        ssl->out_msg[5] = (unsigned char)( content_len      );
+        MBEDTLS_PUT_UINT16_BE( content_len, ssl->out_msg, 4 );
         header_len = 6;
 
         ret = mbedtls_dhm_make_public( &ssl->handshake->dhm_ctx,
@@ -3730,8 +3712,8 @@
             return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
         }
 
-        ssl->out_msg[header_len++] = (unsigned char)( content_len >> 8 );
-        ssl->out_msg[header_len++] = (unsigned char)( content_len      );
+        ssl->out_msg[header_len++] = MBEDTLS_BYTE_1( content_len );
+        ssl->out_msg[header_len++] = MBEDTLS_BYTE_0( content_len );
 
         memcpy( ssl->out_msg + header_len,
                 ssl->conf->psk_identity,
@@ -3782,8 +3764,8 @@
                 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
             }
 
-            ssl->out_msg[header_len++] = (unsigned char)( content_len >> 8 );
-            ssl->out_msg[header_len++] = (unsigned char)( content_len      );
+            ssl->out_msg[header_len++] = MBEDTLS_BYTE_1( content_len );
+            ssl->out_msg[header_len++] = MBEDTLS_BYTE_0( content_len );
 
             ret = mbedtls_dhm_make_public( &ssl->handshake->dhm_ctx,
                     (int) mbedtls_dhm_get_len( &ssl->handshake->dhm_ctx ),
@@ -4065,8 +4047,7 @@
         return( ret );
     }
 
-    ssl->out_msg[4 + offset] = (unsigned char)( n >> 8 );
-    ssl->out_msg[5 + offset] = (unsigned char)( n      );
+    MBEDTLS_PUT_UINT16_BE( n, ssl->out_msg, offset + 4 );
 
     ssl->out_msglen  = 6 + n + offset;
     ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
@@ -4210,23 +4191,8 @@
 {
     int ret = 0;
 
-    if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER || ssl->handshake == NULL )
-        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
-
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "client state: %d", ssl->state ) );
 
-    if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
-        return( ret );
-
-#if defined(MBEDTLS_SSL_PROTO_DTLS)
-    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
-        ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING )
-    {
-        if( ( ret = mbedtls_ssl_flight_transmit( ssl ) ) != 0 )
-            return( ret );
-    }
-#endif /* MBEDTLS_SSL_PROTO_DTLS */
-
     /* Change state now, so that it is right in mbedtls_ssl_read_record(), used
      * by DTLS for dropping out-of-sequence ChangeCipherSpec records */
 #if defined(MBEDTLS_SSL_SESSION_TICKETS)
diff --git a/library/ssl_cookie.c b/library/ssl_cookie.c
index 40b8913..986b141 100644
--- a/library/ssl_cookie.c
+++ b/library/ssl_cookie.c
@@ -165,10 +165,7 @@
     t = ctx->serial++;
 #endif
 
-    (*p)[0] = (unsigned char)( t >> 24 );
-    (*p)[1] = (unsigned char)( t >> 16 );
-    (*p)[2] = (unsigned char)( t >>  8 );
-    (*p)[3] = (unsigned char)( t       );
+    MBEDTLS_PUT_UINT32_BE(t, *p, 0);
     *p += 4;
 
 #if defined(MBEDTLS_THREADING_C)
diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index cc19f47..b4f841a 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -562,6 +562,13 @@
     uint16_t mtu;                       /*!<  Handshake mtu, used to fragment outgoing messages */
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
 
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+    /*! TLS 1.3 transforms for 0-RTT and encrypted handshake messages.
+     *  Those pointers own the transforms they reference. */
+    mbedtls_ssl_transform *transform_handshake;
+    mbedtls_ssl_transform *transform_earlydata;
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
+
     /*
      * Checksum contexts
      */
@@ -740,7 +747,8 @@
 
 #if defined(MBEDTLS_SSL_CONTEXT_SERIALIZATION)
     /* We need the Hello random bytes in order to re-derive keys from the
-     * Master Secret and other session info, see ssl_populate_transform() */
+     * Master Secret and other session info,
+     * see ssl_tls12_populate_transform() */
     unsigned char randbytes[64]; /*!< ServerHello.random+ClientHello.random */
 #endif /* MBEDTLS_SSL_CONTEXT_SERIALIZATION */
 };
@@ -881,6 +889,10 @@
 int mbedtls_ssl_handshake_client_step( mbedtls_ssl_context *ssl );
 int mbedtls_ssl_handshake_server_step( mbedtls_ssl_context *ssl );
 void mbedtls_ssl_handshake_wrapup( mbedtls_ssl_context *ssl );
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+int mbedtls_ssl_handshake_client_step_tls1_3( mbedtls_ssl_context *ssl );
+int mbedtls_ssl_handshake_server_step_tls1_3( mbedtls_ssl_context *ssl );
+#endif
 
 int mbedtls_ssl_send_fatal_handshake_failure( mbedtls_ssl_context *ssl );
 
@@ -971,7 +983,13 @@
                              unsigned update_hs_digest );
 int mbedtls_ssl_fetch_input( mbedtls_ssl_context *ssl, size_t nb_want );
 
-int mbedtls_ssl_write_handshake_msg( mbedtls_ssl_context *ssl );
+int mbedtls_ssl_write_handshake_msg_ext( mbedtls_ssl_context *ssl,
+                                         int update_checksum );
+static inline int mbedtls_ssl_write_handshake_msg( mbedtls_ssl_context *ssl )
+{
+    return( mbedtls_ssl_write_handshake_msg_ext( ssl, 1 /* update checksum */ ) );
+}
+
 int mbedtls_ssl_write_record( mbedtls_ssl_context *ssl, uint8_t force_flush );
 int mbedtls_ssl_flush_output( mbedtls_ssl_context *ssl );
 
@@ -1259,4 +1277,50 @@
 void mbedtls_ssl_flight_free( mbedtls_ssl_flight_item *flight );
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
 
+/**
+ * ssl utils functions for checking configuration.
+ */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+static inline int mbedtls_ssl_conf_is_tls13_only( const mbedtls_ssl_config *conf )
+{
+    if( conf->min_major_ver == MBEDTLS_SSL_MAJOR_VERSION_3 &&
+        conf->max_major_ver == MBEDTLS_SSL_MAJOR_VERSION_3 &&
+        conf->min_minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 &&
+        conf->max_minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
+    {
+        return( 1 );
+    }
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+static inline int mbedtls_ssl_conf_is_tls12_only( const mbedtls_ssl_config *conf )
+{
+    if( conf->min_major_ver == MBEDTLS_SSL_MAJOR_VERSION_3 &&
+        conf->max_major_ver == MBEDTLS_SSL_MAJOR_VERSION_3 &&
+        conf->min_minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 &&
+        conf->max_minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 )
+    {
+        return( 1 );
+    }
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+static inline int mbedtls_ssl_conf_is_hybrid_tls12_tls13( const mbedtls_ssl_config *conf )
+{
+    if( conf->min_major_ver == MBEDTLS_SSL_MAJOR_VERSION_3 &&
+        conf->max_major_ver == MBEDTLS_SSL_MAJOR_VERSION_3 &&
+        conf->min_minor_ver == MBEDTLS_SSL_MINOR_VERSION_3 &&
+        conf->max_minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
+    {
+        return( 1 );
+    }
+    return( 0 );
+}
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 && MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL*/
+
 #endif /* ssl_misc.h */
diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index 76cc2b1..2fe801a 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -384,7 +384,8 @@
 static void ssl_extract_add_data_from_record( unsigned char* add_data,
                                               size_t *add_data_len,
                                               mbedtls_record *rec,
-                                              unsigned minor_ver )
+                                              unsigned minor_ver,
+                                              size_t taglen )
 {
     /* Quoting RFC 5246 (TLS 1.2):
      *
@@ -403,15 +404,37 @@
      *
      * For TLS 1.3, the record sequence number is dropped from the AAD
      * and encoded within the nonce of the AEAD operation instead.
+     * Moreover, the additional data involves the length of the TLS
+     * ciphertext, not the TLS plaintext as in earlier versions.
+     * Quoting RFC 8446 (TLS 1.3):
+     *
+     *      additional_data = TLSCiphertext.opaque_type ||
+     *                        TLSCiphertext.legacy_record_version ||
+     *                        TLSCiphertext.length
+     *
+     * We pass the tag length to this function in order to compute the
+     * ciphertext length from the inner plaintext length rec->data_len via
+     *
+     *     TLSCiphertext.length = TLSInnerPlaintext.length + taglen.
+     *
      */
 
     unsigned char *cur = add_data;
+    size_t ad_len_field = rec->data_len;
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
-    if( minor_ver != MBEDTLS_SSL_MINOR_VERSION_4 )
+    if( minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
+    {
+        /* In TLS 1.3, the AAD contains the length of the TLSCiphertext,
+         * which differs from the length of the TLSInnerPlaintext
+         * by the length of the authentication tag. */
+        ad_len_field += taglen;
+    }
+    else
 #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
     {
         ((void) minor_ver);
+        ((void) taglen);
         memcpy( cur, rec->ctr, sizeof( rec->ctr ) );
         cur += sizeof( rec->ctr );
     }
@@ -431,15 +454,13 @@
         *cur = rec->cid_len;
         cur++;
 
-        cur[0] = ( rec->data_len >> 8 ) & 0xFF;
-        cur[1] = ( rec->data_len >> 0 ) & 0xFF;
+        MBEDTLS_PUT_UINT16_BE( ad_len_field, cur, 0 );
         cur += 2;
     }
     else
 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
     {
-        cur[0] = ( rec->data_len >> 8 ) & 0xFF;
-        cur[1] = ( rec->data_len >> 0 ) & 0xFF;
+        MBEDTLS_PUT_UINT16_BE( ad_len_field, cur, 0 );
         cur += 2;
     }
 
@@ -646,7 +667,8 @@
         unsigned char mac[MBEDTLS_SSL_MAC_ADD];
 
         ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
-                                          transform->minor_ver );
+                                          transform->minor_ver,
+                                          transform->taglen );
 
         mbedtls_md_hmac_update( &transform->md_ctx_enc, add_data,
                                 add_data_len );
@@ -743,7 +765,8 @@
          * This depends on the TLS version.
          */
         ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
-                                          transform->minor_ver );
+                                          transform->minor_ver,
+                                          transform->taglen );
 
         MBEDTLS_SSL_DEBUG_BUF( 4, "IV used (internal)",
                                iv, transform->ivlen );
@@ -897,7 +920,8 @@
             }
 
             ssl_extract_add_data_from_record( add_data, &add_data_len,
-                                              rec, transform->minor_ver );
+                                              rec, transform->minor_ver,
+                                              transform->taglen );
 
             MBEDTLS_SSL_DEBUG_MSG( 3, ( "using encrypt then mac" ) );
             MBEDTLS_SSL_DEBUG_BUF( 4, "MAC'd meta-data", add_data,
@@ -1304,7 +1328,8 @@
          * This depends on the TLS version.
          */
         ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
-                                          transform->minor_ver );
+                                          transform->minor_ver,
+                                          transform->taglen );
         MBEDTLS_SSL_DEBUG_BUF( 4, "additional data used for AEAD",
                                add_data, add_data_len );
 
@@ -1414,7 +1439,8 @@
              * Further, we still know that data_len > minlen */
             rec->data_len -= transform->maclen;
             ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
-                                              transform->minor_ver );
+                                              transform->minor_ver,
+                                              transform->taglen );
 
             /* Calculate expected MAC. */
             MBEDTLS_SSL_DEBUG_BUF( 4, "MAC'd meta-data", add_data,
@@ -1606,7 +1632,8 @@
          */
         rec->data_len -= transform->maclen;
         ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
-                                          transform->minor_ver );
+                                          transform->minor_ver,
+                                          transform->taglen );
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
         /*
@@ -2226,13 +2253,13 @@
              * Handshake headers: type(1) len(3) seq(2) f_off(3) f_len(3) */
             memcpy( ssl->out_msg, cur->p, 6 );
 
-            ssl->out_msg[6] = ( ( frag_off >> 16 ) & 0xff );
-            ssl->out_msg[7] = ( ( frag_off >>  8 ) & 0xff );
-            ssl->out_msg[8] = ( ( frag_off       ) & 0xff );
+            ssl->out_msg[6] = MBEDTLS_BYTE_2( frag_off );
+            ssl->out_msg[7] = MBEDTLS_BYTE_1( frag_off );
+            ssl->out_msg[8] = MBEDTLS_BYTE_0( frag_off );
 
-            ssl->out_msg[ 9] = ( ( cur_hs_frag_len >> 16 ) & 0xff );
-            ssl->out_msg[10] = ( ( cur_hs_frag_len >>  8 ) & 0xff );
-            ssl->out_msg[11] = ( ( cur_hs_frag_len       ) & 0xff );
+            ssl->out_msg[ 9] = MBEDTLS_BYTE_2( cur_hs_frag_len );
+            ssl->out_msg[10] = MBEDTLS_BYTE_1( cur_hs_frag_len );
+            ssl->out_msg[11] = MBEDTLS_BYTE_0( cur_hs_frag_len );
 
             MBEDTLS_SSL_DEBUG_BUF( 3, "handshake header", ssl->out_msg, 12 );
 
@@ -2360,7 +2387,8 @@
  *      (including handshake headers but excluding record headers)
  *   - ssl->out_msg: the record contents (handshake headers + content)
  */
-int mbedtls_ssl_write_handshake_msg( mbedtls_ssl_context *ssl )
+int mbedtls_ssl_write_handshake_msg_ext( mbedtls_ssl_context *ssl,
+                                         int update_checksum )
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     const size_t hs_len = ssl->out_msglen - 4;
@@ -2421,9 +2449,9 @@
      */
     if( ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
     {
-        ssl->out_msg[1] = (unsigned char)( hs_len >> 16 );
-        ssl->out_msg[2] = (unsigned char)( hs_len >>  8 );
-        ssl->out_msg[3] = (unsigned char)( hs_len       );
+        ssl->out_msg[1] = MBEDTLS_BYTE_2( hs_len );
+        ssl->out_msg[2] = MBEDTLS_BYTE_1( hs_len );
+        ssl->out_msg[3] = MBEDTLS_BYTE_0( hs_len );
 
         /*
          * DTLS has additional fields in the Handshake layer,
@@ -2451,8 +2479,7 @@
             /* Write message_seq and update it, except for HelloRequest */
             if( hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
             {
-                ssl->out_msg[4] = ( ssl->handshake->out_msg_seq >> 8 ) & 0xFF;
-                ssl->out_msg[5] = ( ssl->handshake->out_msg_seq      ) & 0xFF;
+                MBEDTLS_PUT_UINT16_BE( ssl->handshake->out_msg_seq, ssl->out_msg, 4 );
                 ++( ssl->handshake->out_msg_seq );
             }
             else
@@ -2469,7 +2496,7 @@
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
 
         /* Update running hashes of handshake messages seen */
-        if( hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
+        if( hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST && update_checksum != 0 )
             ssl->handshake->update_checksum( ssl, ssl->out_msg, ssl->out_msglen );
     }
 
@@ -2536,8 +2563,7 @@
                            ssl->conf->transport, ssl->out_hdr + 1 );
 
         memcpy( ssl->out_ctr, ssl->cur_out_ctr, 8 );
-        ssl->out_len[0] = (unsigned char)( len >> 8 );
-        ssl->out_len[1] = (unsigned char)( len      );
+        MBEDTLS_PUT_UINT16_BE( len, ssl->out_len, 0);
 
         if( ssl->transform_out != NULL )
         {
@@ -2577,8 +2603,7 @@
             memcpy( ssl->out_cid, rec.cid, rec.cid_len );
 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
             ssl->out_msglen = len = rec.data_len;
-            ssl->out_len[0] = (unsigned char)( rec.data_len >> 8 );
-            ssl->out_len[1] = (unsigned char)( rec.data_len      );
+            MBEDTLS_PUT_UINT16_BE( rec.data_len, ssl->out_len, 0 );
         }
 
         protected_record_size = len + mbedtls_ssl_out_hdr_len( ssl );
@@ -3150,12 +3175,11 @@
     /* Go back and fill length fields */
     obuf[27] = (unsigned char)( *olen - 28 );
 
-    obuf[14] = obuf[22] = (unsigned char)( ( *olen - 25 ) >> 16 );
-    obuf[15] = obuf[23] = (unsigned char)( ( *olen - 25 ) >>  8 );
-    obuf[16] = obuf[24] = (unsigned char)( ( *olen - 25 )       );
+    obuf[14] = obuf[22] = MBEDTLS_BYTE_2( *olen - 25 );
+    obuf[15] = obuf[23] = MBEDTLS_BYTE_1( *olen - 25 );
+    obuf[16] = obuf[24] = MBEDTLS_BYTE_0( *olen - 25 );
 
-    obuf[11] = (unsigned char)( ( *olen - 13 ) >>  8 );
-    obuf[12] = (unsigned char)( ( *olen - 13 )       );
+    MBEDTLS_PUT_UINT16_BE( *olen - 13, obuf, 11 );
 
     return( MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED );
 }
@@ -4535,8 +4559,7 @@
     ssl->in_hdr[0] = rec.type;
     ssl->in_msg    = rec.buf + rec.data_offset;
     ssl->in_msglen = rec.data_len;
-    ssl->in_len[0] = (unsigned char)( rec.data_len >> 8 );
-    ssl->in_len[1] = (unsigned char)( rec.data_len      );
+    MBEDTLS_PUT_UINT16_BE( rec.data_len, ssl->in_len, 0 );
 
     return( 0 );
 }
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index d82ec04..b8c4314 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -1848,8 +1848,7 @@
         for( j = 0, p = buf + ciph_offset + 2; j < ciph_len; j += 2, p += 2 )
             for( i = 0; ciphersuites[i] != 0; i++ )
             {
-                if( p[0] != ( ( ciphersuites[i] >> 8 ) & 0xFF ) ||
-                    p[1] != ( ( ciphersuites[i]      ) & 0xFF ) )
+                if( MBEDTLS_GET_UINT16_BE(p, 0) != ciphersuites[i] )
                     continue;
 
                 got_common_suite = 1;
@@ -1865,8 +1864,7 @@
         for( i = 0; ciphersuites[i] != 0; i++ )
             for( j = 0, p = buf + ciph_offset + 2; j < ciph_len; j += 2, p += 2 )
             {
-                if( p[0] != ( ( ciphersuites[i] >> 8 ) & 0xFF ) ||
-                    p[1] != ( ( ciphersuites[i]      ) & 0xFF ) )
+                if( MBEDTLS_GET_UINT16_BE(p, 0) != ciphersuites[i] )
                     continue;
 
                 got_common_suite = 1;
@@ -1970,12 +1968,11 @@
      *      opaque cid<0..2^8-1>;
      *   } ConnectionId;
     */
-
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_CID, p, 0 );
+    p += 2;
     ext_len = (size_t) ssl->own_cid_len + 1;
-    *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( ext_len, p, 0 );
+    p += 2;
 
     *p++ = (uint8_t) ssl->own_cid_len;
     memcpy( p, ssl->own_cid, ssl->own_cid_len );
@@ -2016,8 +2013,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding encrypt then mac extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC, p, 0 );
+    p += 2;
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -2042,8 +2039,8 @@
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding extended master secret "
                         "extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET, p, 0 );
+    p += 2;
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -2067,8 +2064,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding session ticket extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SESSION_TICKET, p, 0 );
+    p += 2;
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -2091,8 +2088,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, secure renegotiation extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO, p, 0 );
+    p += 2;
 
 #if defined(MBEDTLS_SSL_RENEGOTIATION)
     if( ssl->renego_status != MBEDTLS_SSL_INITIAL_HANDSHAKE )
@@ -2132,8 +2129,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, max_fragment_length extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH, p, 0 );
+    p += 2;
 
     *p++ = 0x00;
     *p++ = 1;
@@ -2162,8 +2159,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, supported_point_formats extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS, p, 0 );
+    p += 2;
 
     *p++ = 0x00;
     *p++ = 2;
@@ -2200,8 +2197,8 @@
         return;
     }
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ECJPAKE_KKPP >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ECJPAKE_KKPP      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_ECJPAKE_KKPP, p, 0 );
+    p += 2;
 
     ret = mbedtls_ecjpake_write_round_one( &ssl->handshake->ecjpake_ctx,
                                         p + 2, end - p - 2, &kkpp_len,
@@ -2212,8 +2209,8 @@
         return;
     }
 
-    *p++ = (unsigned char)( ( kkpp_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( kkpp_len      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( kkpp_len, p, 0 );
+    p += 2;
 
     *olen = kkpp_len + 4;
 }
@@ -2238,18 +2235,15 @@
      * 6 . 6    protocol name length
      * 7 . 7+n  protocol name
      */
-    buf[0] = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN >> 8 ) & 0xFF );
-    buf[1] = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_ALPN, buf, 0);
 
     *olen = 7 + strlen( ssl->alpn_chosen );
 
-    buf[2] = (unsigned char)( ( ( *olen - 4 ) >> 8 ) & 0xFF );
-    buf[3] = (unsigned char)( ( ( *olen - 4 )      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( *olen - 4, buf, 2 );
 
-    buf[4] = (unsigned char)( ( ( *olen - 6 ) >> 8 ) & 0xFF );
-    buf[5] = (unsigned char)( ( ( *olen - 6 )      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( *olen - 6, buf, 4 );
 
-    buf[6] = (unsigned char)( ( ( *olen - 7 )      ) & 0xFF );
+    buf[6] = MBEDTLS_BYTE_0( *olen - 7 );
 
     memcpy( buf + 7, ssl->alpn_chosen, *olen - 7 );
 }
@@ -2294,15 +2288,13 @@
     }
 
     /* extension */
-    buf[0] = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP >> 8 ) & 0xFF );
-    buf[1] = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP      ) & 0xFF );
+    MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_USE_SRTP, buf, 0 );
     /*
      * total length 5 and mki value: only one profile(2 bytes)
      *              and length(2 bytes) and srtp_mki  )
      */
     ext_len = 5 + mki_len;
-    buf[2] = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-    buf[3] = (unsigned char)( ext_len & 0xFF );
+    MBEDTLS_PUT_UINT16_BE( ext_len, buf, 2 );
 
     /* protection profile length: 2 */
     buf[4] = 0x00;
@@ -2311,8 +2303,7 @@
                                 ssl->dtls_srtp_info.chosen_dtls_srtp_profile );
     if( profile_value != MBEDTLS_TLS_SRTP_UNSET )
     {
-        buf[6] = (unsigned char)( ( profile_value >> 8 ) & 0xFF );
-        buf[7] = (unsigned char)( profile_value & 0xFF );
+        MBEDTLS_PUT_UINT16_BE( profile_value, buf, 6 );
     }
     else
     {
@@ -2494,10 +2485,8 @@
 
 #if defined(MBEDTLS_HAVE_TIME)
     t = mbedtls_time( NULL );
-    *p++ = (unsigned char)( t >> 24 );
-    *p++ = (unsigned char)( t >> 16 );
-    *p++ = (unsigned char)( t >>  8 );
-    *p++ = (unsigned char)( t       );
+    MBEDTLS_PUT_UINT32_BE( t, p, 0 );
+    p += 4;
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, current time: %" MBEDTLS_PRINTF_LONGLONG,
                                 (long long) t ) );
@@ -2578,9 +2567,9 @@
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "%s session has been resumed",
                    ssl->handshake->resume ? "a" : "no" ) );
 
-    *p++ = (unsigned char)( ssl->session_negotiate->ciphersuite >> 8 );
-    *p++ = (unsigned char)( ssl->session_negotiate->ciphersuite      );
-    *p++ = (unsigned char)( ssl->session_negotiate->compression      );
+    MBEDTLS_PUT_UINT16_BE( ssl->session_negotiate->ciphersuite, p, 0 );
+    p += 2;
+    *p++ = MBEDTLS_BYTE_0( ssl->session_negotiate->compression );
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, chosen ciphersuite: %s",
            mbedtls_ssl_get_ciphersuite_name( ssl->session_negotiate->ciphersuite ) ) );
@@ -2648,9 +2637,8 @@
 
     if( ext_len > 0 )
     {
-        *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
-        p += ext_len;
+        MBEDTLS_PUT_UINT16_BE( ext_len, p, 0 );
+        p += 2 + ext_len;
     }
 
     ssl->out_msglen  = p - buf;
@@ -2785,8 +2773,7 @@
 #endif
         }
 
-        p[0] = (unsigned char)( sa_len >> 8 );
-        p[1] = (unsigned char)( sa_len      );
+        MBEDTLS_PUT_UINT16_BE( sa_len, p, 0 );
         sa_len += 2;
         p += sa_len;
     }
@@ -2826,8 +2813,8 @@
                 break;
             }
 
-            *p++ = (unsigned char)( dn_size >> 8 );
-            *p++ = (unsigned char)( dn_size      );
+            MBEDTLS_PUT_UINT16_BE( dn_size, p, 0 );
+            p += 2;
             memcpy( p, crt->subject_raw.p, dn_size );
             p += dn_size;
 
@@ -2841,8 +2828,7 @@
     ssl->out_msglen  = p - buf;
     ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
     ssl->out_msg[0]  = MBEDTLS_SSL_HS_CERTIFICATE_REQUEST;
-    ssl->out_msg[4 + ct_len + sa_len] = (unsigned char)( total_dn_size  >> 8 );
-    ssl->out_msg[5 + ct_len + sa_len] = (unsigned char)( total_dn_size       );
+    MBEDTLS_PUT_UINT16_BE( total_dn_size, ssl->out_msg, 4 + ct_len + sa_len );
 
     ret = mbedtls_ssl_write_handshake_msg( ssl );
 
@@ -3320,8 +3306,8 @@
 #if defined(MBEDTLS_KEY_EXCHANGE_WITH_SERVER_SIGNATURE_ENABLED)
     if( signature_len != 0 )
     {
-        ssl->out_msg[ssl->out_msglen++] = (unsigned char)( signature_len >> 8 );
-        ssl->out_msg[ssl->out_msglen++] = (unsigned char)( signature_len      );
+        ssl->out_msg[ssl->out_msglen++] = MBEDTLS_BYTE_1( signature_len );
+        ssl->out_msg[ssl->out_msglen++] = MBEDTLS_BYTE_0( signature_len );
 
         MBEDTLS_SSL_DEBUG_BUF( 3, "my signature",
                                ssl->out_msg + ssl->out_msglen,
@@ -3478,8 +3464,8 @@
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
         return( MBEDTLS_ERR_SSL_DECODE_ERROR );
     }
-    if( *p++ != ( ( len >> 8 ) & 0xFF ) ||
-        *p++ != ( ( len      ) & 0xFF ) )
+    if( *p++ != MBEDTLS_BYTE_1( len ) ||
+        *p++ != MBEDTLS_BYTE_0( len ) )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
         return( MBEDTLS_ERR_SSL_DECODE_ERROR );
@@ -4223,14 +4209,8 @@
         tlen = 0;
     }
 
-    ssl->out_msg[4] = ( lifetime >> 24 ) & 0xFF;
-    ssl->out_msg[5] = ( lifetime >> 16 ) & 0xFF;
-    ssl->out_msg[6] = ( lifetime >>  8 ) & 0xFF;
-    ssl->out_msg[7] = ( lifetime       ) & 0xFF;
-
-    ssl->out_msg[8] = (unsigned char)( ( tlen >> 8 ) & 0xFF );
-    ssl->out_msg[9] = (unsigned char)( ( tlen      ) & 0xFF );
-
+    MBEDTLS_PUT_UINT32_BE( lifetime, ssl->out_msg, 4 );
+    MBEDTLS_PUT_UINT16_BE( tlen, ssl->out_msg, 8 );
     ssl->out_msglen = 10 + tlen;
 
     /*
@@ -4258,23 +4238,8 @@
 {
     int ret = 0;
 
-    if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER || ssl->handshake == NULL )
-        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
-
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "server state: %d", ssl->state ) );
 
-    if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
-        return( ret );
-
-#if defined(MBEDTLS_SSL_PROTO_DTLS)
-    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
-        ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING )
-    {
-        if( ( ret = mbedtls_ssl_flight_transmit( ssl ) ) != 0 )
-            return( ret );
-    }
-#endif /* MBEDTLS_SSL_PROTO_DTLS */
-
     switch( ssl->state )
     {
         case MBEDTLS_SSL_HELLO_REQUEST:
diff --git a/library/ssl_ticket.c b/library/ssl_ticket.c
index 940e1a6..bce9a1c 100644
--- a/library/ssl_ticket.c
+++ b/library/ssl_ticket.c
@@ -245,8 +245,7 @@
     {
          goto cleanup;
     }
-    state_len_bytes[0] = ( clear_len >> 8 ) & 0xff;
-    state_len_bytes[1] = ( clear_len      ) & 0xff;
+    MBEDTLS_PUT_UINT16_BE( clear_len, state_len_bytes, 0 );
 
     /* Encrypt and authenticate */
     if( ( ret = mbedtls_cipher_auth_encrypt_ext( &key->ctx,
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index bb5ddc4..5cd47e6 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -664,14 +664,14 @@
  *        - MBEDTLS_SSL_EXPORT_KEYS: ssl->conf->{f,p}_export_keys
  *        - MBEDTLS_DEBUG_C: ssl->conf->{f,p}_dbg
  */
-static int ssl_populate_transform( mbedtls_ssl_transform *transform,
+static int ssl_tls12_populate_transform( mbedtls_ssl_transform *transform,
                                    int ciphersuite,
                                    const unsigned char master[48],
-#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
-#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC) && \
+    defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
                                    int encrypt_then_mac,
-#endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
-#endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */
+#endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC &&
+          MBEDTLS_SSL_SOME_SUITES_USE_MAC */
                                    ssl_tls_prf_t tls_prf,
                                    const unsigned char randbytes[64],
                                    int minor_ver,
@@ -713,6 +713,15 @@
     memcpy( transform->randbytes, randbytes, sizeof( transform->randbytes ) );
 #endif
 
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+    if( minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
+    {
+        /* At the moment, we keep TLS <= 1.2 and TLS 1.3 transform
+         * generation separate. This should never happen. */
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
+
     /*
      * Get various info structures
      */
@@ -805,19 +814,10 @@
          *   sequence number).
          */
         transform->ivlen = 12;
-#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
-        if( minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
-        {
+        if( cipher_info->mode == MBEDTLS_MODE_CHACHAPOLY )
             transform->fixed_ivlen = 12;
-        }
         else
-#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
-        {
-            if( cipher_info->mode == MBEDTLS_MODE_CHACHAPOLY )
-                transform->fixed_ivlen = 12;
-            else
-                transform->fixed_ivlen = 4;
-        }
+            transform->fixed_ivlen = 4;
 
         /* Minimum length of encrypted record */
         explicit_ivlen = transform->ivlen - transform->fixed_ivlen;
@@ -1327,22 +1327,22 @@
     }
 
     /* Populate transform structure */
-    ret = ssl_populate_transform( ssl->transform_negotiate,
-                                  ssl->session_negotiate->ciphersuite,
-                                  ssl->session_negotiate->master,
-#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
-#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
-                                  ssl->session_negotiate->encrypt_then_mac,
-#endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
-#endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */
-                                  ssl->handshake->tls_prf,
-                                  ssl->handshake->randbytes,
-                                  ssl->minor_ver,
-                                  ssl->conf->endpoint,
-                                  ssl );
+    ret = ssl_tls12_populate_transform( ssl->transform_negotiate,
+                                        ssl->session_negotiate->ciphersuite,
+                                        ssl->session_negotiate->master,
+#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC) && \
+    defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+                                        ssl->session_negotiate->encrypt_then_mac,
+#endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC &&
+          MBEDTLS_SSL_SOME_SUITES_USE_MAC */
+                                        ssl->handshake->tls_prf,
+                                        ssl->handshake->randbytes,
+                                        ssl->minor_ver,
+                                        ssl->conf->endpoint,
+                                        ssl );
     if( ret != 0 )
     {
-        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_populate_transform", ret );
+        MBEDTLS_SSL_DEBUG_RET( 1, "ssl_tls12_populate_transform", ret );
         return( ret );
     }
 
@@ -1487,8 +1487,8 @@
         if( end - p < 2 )
             return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
 
-        *(p++) = (unsigned char)( psk_len >> 8 );
-        *(p++) = (unsigned char)( psk_len      );
+        MBEDTLS_PUT_UINT16_BE( psk_len, p, 0 );
+        p += 2;
 
         if( end < p || (size_t)( end - p ) < psk_len )
             return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
@@ -1528,9 +1528,8 @@
             MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_dhm_calc_secret", ret );
             return( ret );
         }
-        *(p++) = (unsigned char)( len >> 8 );
-        *(p++) = (unsigned char)( len );
-        p += len;
+        MBEDTLS_PUT_UINT16_BE( len, p, 0 );
+        p += 2 + len;
 
         MBEDTLS_SSL_DEBUG_MPI( 3, "DHM: K ", &ssl->handshake->dhm_ctx.K  );
     }
@@ -1550,9 +1549,8 @@
             return( ret );
         }
 
-        *(p++) = (unsigned char)( zlen >> 8 );
-        *(p++) = (unsigned char)( zlen      );
-        p += zlen;
+        MBEDTLS_PUT_UINT16_BE( zlen, p, 0 );
+        p += 2 + zlen;
 
         MBEDTLS_SSL_DEBUG_ECDH( 3, &ssl->handshake->ecdh_ctx,
                                 MBEDTLS_DEBUG_ECDH_Z );
@@ -1568,8 +1566,8 @@
     if( end - p < 2 )
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
 
-    *(p++) = (unsigned char)( psk_len >> 8 );
-    *(p++) = (unsigned char)( psk_len      );
+    MBEDTLS_PUT_UINT16_BE( psk_len, p, 0 );
+    p += 2;
 
     if( end < p || (size_t)( end - p ) < psk_len )
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
@@ -1746,17 +1744,17 @@
             return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
         }
 
-        ssl->out_msg[i    ] = (unsigned char)( n >> 16 );
-        ssl->out_msg[i + 1] = (unsigned char)( n >>  8 );
-        ssl->out_msg[i + 2] = (unsigned char)( n       );
+        ssl->out_msg[i    ] = MBEDTLS_BYTE_2( n );
+        ssl->out_msg[i + 1] = MBEDTLS_BYTE_1( n );
+        ssl->out_msg[i + 2] = MBEDTLS_BYTE_0( n );
 
         i += 3; memcpy( ssl->out_msg + i, crt->raw.p, n );
         i += n; crt = crt->next;
     }
 
-    ssl->out_msg[4]  = (unsigned char)( ( i - 7 ) >> 16 );
-    ssl->out_msg[5]  = (unsigned char)( ( i - 7 ) >>  8 );
-    ssl->out_msg[6]  = (unsigned char)( ( i - 7 )       );
+    ssl->out_msg[4]  = MBEDTLS_BYTE_2( i - 7 );
+    ssl->out_msg[5]  = MBEDTLS_BYTE_1( i - 7 );
+    ssl->out_msg[6]  = MBEDTLS_BYTE_0( i - 7 );
 
     ssl->out_msglen  = i;
     ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
@@ -3142,6 +3140,53 @@
     memset( ssl, 0, sizeof( mbedtls_ssl_context ) );
 }
 
+static int ssl_conf_version_check( const mbedtls_ssl_context *ssl )
+{
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+    if( mbedtls_ssl_conf_is_tls13_only( ssl->conf ) )
+    {
+        if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
+        {
+             MBEDTLS_SSL_DEBUG_MSG( 1, ( "DTLS 1.3 is not yet supported" ) );
+             return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+        }
+        MBEDTLS_SSL_DEBUG_MSG( 4, ( "The SSL configuration is tls13 only." ) );
+        return( 0 );
+    }
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+    if( mbedtls_ssl_conf_is_tls12_only( ssl->conf ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 4, ( "The SSL configuration is tls12 only." ) );
+        return( 0 );
+    }
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+    if( mbedtls_ssl_conf_is_hybrid_tls12_tls13( ssl->conf ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "Hybrid TLS 1.2 + TLS 1.3 configurations are not yet supported" ) );
+        return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+    }
+#endif
+
+    MBEDTLS_SSL_DEBUG_MSG( 1, ( "The SSL configuration is invalid." ) );
+    return( MBEDTLS_ERR_SSL_BAD_CONFIG );
+}
+
+static int ssl_conf_check(const mbedtls_ssl_context *ssl)
+{
+    int ret;
+    ret = ssl_conf_version_check( ssl );
+    if( ret != 0 )
+        return( ret );
+
+    /* Space for further checks */
+
+    return( 0 );
+}
+
 /*
  * Setup an SSL context
  */
@@ -3155,6 +3200,9 @@
 
     ssl->conf = conf;
 
+    if( ( ret = ssl_conf_check( ssl ) ) != 0 )
+        return( ret );
+
     /*
      * Prepare base structures
      */
@@ -3230,9 +3278,9 @@
  * If partial is non-zero, keep data in the input buffer and client ID.
  * (Use when a DTLS client reconnects from the same port.)
  */
-int mbedtls_ssl_session_reset_int( mbedtls_ssl_context *ssl, int partial )
+static void ssl_session_reset_msg_layer( mbedtls_ssl_context *ssl,
+                                         int partial )
 {
-    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
     size_t in_buf_len = ssl->in_buf_len;
     size_t out_buf_len = ssl->out_buf_len;
@@ -3241,16 +3289,65 @@
     size_t out_buf_len = MBEDTLS_SSL_OUT_BUFFER_LEN;
 #endif
 
-#if !defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) ||     \
-    !defined(MBEDTLS_SSL_SRV_C)
-    ((void) partial);
+#if !defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) || !defined(MBEDTLS_SSL_SRV_C)
+    partial = 0;
 #endif
 
-    ssl->state = MBEDTLS_SSL_HELLO_REQUEST;
-
     /* Cancel any possibly running timer */
     mbedtls_ssl_set_timer( ssl, 0 );
 
+    mbedtls_ssl_reset_in_out_pointers( ssl );
+
+    /* Reset incoming message parsing */
+    ssl->in_offt    = NULL;
+    ssl->nb_zero    = 0;
+    ssl->in_msgtype = 0;
+    ssl->in_msglen  = 0;
+    ssl->in_hslen   = 0;
+    ssl->keep_current_message = 0;
+    ssl->transform_in  = NULL;
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    ssl->next_record_offset = 0;
+    ssl->in_epoch = 0;
+#endif
+
+    /* Keep current datagram if partial == 1 */
+    if( partial == 0 )
+    {
+        ssl->in_left = 0;
+        memset( ssl->in_buf, 0, in_buf_len );
+    }
+
+    /* Reset outgoing message writing */
+    ssl->out_msgtype = 0;
+    ssl->out_msglen  = 0;
+    ssl->out_left    = 0;
+    memset( ssl->out_buf, 0, out_buf_len );
+    memset( ssl->cur_out_ctr, 0, sizeof( ssl->cur_out_ctr ) );
+    ssl->transform_out = NULL;
+
+#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
+    mbedtls_ssl_dtls_replay_reset( ssl );
+#endif
+
+    if( ssl->transform )
+    {
+        mbedtls_ssl_transform_free( ssl->transform );
+        mbedtls_free( ssl->transform );
+        ssl->transform = NULL;
+    }
+}
+
+int mbedtls_ssl_session_reset_int( mbedtls_ssl_context *ssl, int partial )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    ssl->state = MBEDTLS_SSL_HELLO_REQUEST;
+
+    ssl_session_reset_msg_layer( ssl, partial );
+
+    /* Reset renegotiation state */
 #if defined(MBEDTLS_SSL_RENEGOTIATION)
     ssl->renego_status = MBEDTLS_SSL_INITIAL_HANDSHAKE;
     ssl->renego_records_seen = 0;
@@ -3261,53 +3358,8 @@
 #endif
     ssl->secure_renegotiation = MBEDTLS_SSL_LEGACY_RENEGOTIATION;
 
-    ssl->in_offt = NULL;
-    mbedtls_ssl_reset_in_out_pointers( ssl );
-
-    ssl->in_msgtype = 0;
-    ssl->in_msglen = 0;
-#if defined(MBEDTLS_SSL_PROTO_DTLS)
-    ssl->next_record_offset = 0;
-    ssl->in_epoch = 0;
-#endif
-#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
-    mbedtls_ssl_dtls_replay_reset( ssl );
-#endif
-
-    ssl->in_hslen = 0;
-    ssl->nb_zero = 0;
-
-    ssl->keep_current_message = 0;
-
-    ssl->out_msgtype = 0;
-    ssl->out_msglen = 0;
-    ssl->out_left = 0;
-
-    memset( ssl->cur_out_ctr, 0, sizeof( ssl->cur_out_ctr ) );
-
-    ssl->transform_in = NULL;
-    ssl->transform_out = NULL;
-
-    ssl->session_in = NULL;
+    ssl->session_in  = NULL;
     ssl->session_out = NULL;
-
-    memset( ssl->out_buf, 0, out_buf_len );
-
-#if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
-    if( partial == 0 )
-#endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */
-    {
-        ssl->in_left = 0;
-        memset( ssl->in_buf, 0, in_buf_len );
-    }
-
-    if( ssl->transform )
-    {
-        mbedtls_ssl_transform_free( ssl->transform );
-        mbedtls_free( ssl->transform );
-        ssl->transform = NULL;
-    }
-
     if( ssl->session )
     {
         mbedtls_ssl_session_free( ssl->session );
@@ -3883,6 +3935,15 @@
 {
     conf->sig_hashes = hashes;
 }
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+/* Configure allowed signature algorithms for use in TLS 1.3 */
+void mbedtls_ssl_conf_sig_algs( mbedtls_ssl_config *conf,
+                                const uint16_t* sig_algs )
+{
+    conf->tls13_sig_algs = sig_algs;
+}
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
 #endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
 
 #if defined(MBEDTLS_ECP_C)
@@ -4519,8 +4580,8 @@
     MBEDTLS_VERSION_MAJOR,
     MBEDTLS_VERSION_MINOR,
     MBEDTLS_VERSION_PATCH,
-    ( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG >> 8 ) & 0xFF,
-    ( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG >> 0 ) & 0xFF,
+    MBEDTLS_BYTE_1( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
+    MBEDTLS_BYTE_0( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
 };
 
 /*
@@ -4601,14 +4662,8 @@
     {
         start = (uint64_t) session->start;
 
-        *p++ = (unsigned char)( ( start >> 56 ) & 0xFF );
-        *p++ = (unsigned char)( ( start >> 48 ) & 0xFF );
-        *p++ = (unsigned char)( ( start >> 40 ) & 0xFF );
-        *p++ = (unsigned char)( ( start >> 32 ) & 0xFF );
-        *p++ = (unsigned char)( ( start >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( start >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( start >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( start       ) & 0xFF );
+        MBEDTLS_PUT_UINT64_BE( start, p, 0 );
+        p += 8;
     }
 #endif /* MBEDTLS_HAVE_TIME */
 
@@ -4624,22 +4679,20 @@
 
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( session->ciphersuite >> 8 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ciphersuite      ) & 0xFF );
+        MBEDTLS_PUT_UINT16_BE( session->ciphersuite, p, 0 );
+        p += 2;
 
-        *p++ = (unsigned char)( session->compression & 0xFF );
+        *p++ = MBEDTLS_BYTE_0( session->compression );
 
-        *p++ = (unsigned char)( session->id_len & 0xFF );
+        *p++ = MBEDTLS_BYTE_0( session->id_len );
         memcpy( p, session->id, 32 );
         p += 32;
 
         memcpy( p, session->master, 48 );
         p += 48;
 
-        *p++ = (unsigned char)( ( session->verify_result >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->verify_result >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->verify_result >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->verify_result       ) & 0xFF );
+        MBEDTLS_PUT_UINT32_BE( session->verify_result, p, 0 );
+        p += 4;
     }
 
     /*
@@ -4656,9 +4709,9 @@
 
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( cert_len >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( cert_len >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( cert_len       ) & 0xFF );
+        *p++ = MBEDTLS_BYTE_2( cert_len );
+        *p++ = MBEDTLS_BYTE_1( cert_len );
+        *p++ = MBEDTLS_BYTE_0( cert_len );
 
         if( session->peer_cert != NULL )
         {
@@ -4699,9 +4752,9 @@
 
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( session->ticket_len >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_len >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_len       ) & 0xFF );
+        *p++ = MBEDTLS_BYTE_2( session->ticket_len );
+        *p++ = MBEDTLS_BYTE_1( session->ticket_len );
+        *p++ = MBEDTLS_BYTE_0( session->ticket_len );
 
         if( session->ticket != NULL )
         {
@@ -4709,10 +4762,8 @@
             p += session->ticket_len;
         }
 
-        *p++ = (unsigned char)( ( session->ticket_lifetime >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_lifetime >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_lifetime >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_lifetime       ) & 0xFF );
+        MBEDTLS_PUT_UINT32_BE( session->ticket_lifetime, p, 0 );
+        p += 4;
     }
 #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
 
@@ -4730,7 +4781,7 @@
     used += 1;
 
     if( used <= buf_len )
-        *p++ = (unsigned char)( ( session->encrypt_then_mac ) & 0xFF );
+        *p++ = MBEDTLS_BYTE_0( session->encrypt_then_mac );
 #endif
 
     return( used );
@@ -5076,20 +5127,68 @@
 /*
  * Perform a single step of the SSL handshake
  */
+static int ssl_prepare_handshake_step( mbedtls_ssl_context *ssl )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
+        return( ret );
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+    if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
+        ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING )
+    {
+        if( ( ret = mbedtls_ssl_flight_transmit( ssl ) ) != 0 )
+            return( ret );
+    }
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+
+    return( ret );
+}
+
 int mbedtls_ssl_handshake_step( mbedtls_ssl_context *ssl )
 {
-    int ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
-    if( ssl == NULL || ssl->conf == NULL )
+    if( ssl            == NULL                       ||
+        ssl->conf      == NULL                       ||
+        ssl->handshake == NULL                       ||
+        ssl->state     == MBEDTLS_SSL_HANDSHAKE_OVER )
+    {
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    ret = ssl_prepare_handshake_step( ssl );
+    if( ret != 0 )
+        return( ret );
 
 #if defined(MBEDTLS_SSL_CLI_C)
     if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
-        ret = mbedtls_ssl_handshake_client_step( ssl );
+    {
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+        if( mbedtls_ssl_conf_is_tls13_only( ssl->conf ) )
+            ret = mbedtls_ssl_handshake_client_step_tls1_3( ssl );
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        if( mbedtls_ssl_conf_is_tls12_only( ssl->conf ) )
+            ret = mbedtls_ssl_handshake_client_step( ssl );
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+    }
 #endif
 #if defined(MBEDTLS_SSL_SRV_C)
     if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER )
-        ret = mbedtls_ssl_handshake_server_step( ssl );
+    {
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+        if( mbedtls_ssl_conf_is_tls13_only( ssl->conf ) )
+            ret = mbedtls_ssl_handshake_server_step_tls1_3( ssl );
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        if( mbedtls_ssl_conf_is_tls12_only( ssl->conf ) )
+            ret = mbedtls_ssl_handshake_server_step( ssl );
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+    }
 #endif
 
     return( ret );
@@ -5393,6 +5492,13 @@
     handle_buffer_resizing( ssl, 1, mbedtls_ssl_get_input_buflen( ssl ),
                                     mbedtls_ssl_get_output_buflen( ssl ) );
 #endif
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+    mbedtls_free( handshake->transform_earlydata );
+    mbedtls_free( handshake->transform_handshake );
+    handshake->transform_earlydata = NULL;
+    handshake->transform_handshake = NULL;
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
 }
 
 void mbedtls_ssl_session_free( mbedtls_ssl_session *session )
@@ -5450,11 +5556,11 @@
     MBEDTLS_VERSION_MAJOR,
     MBEDTLS_VERSION_MINOR,
     MBEDTLS_VERSION_PATCH,
-    ( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG >> 8 ) & 0xFF,
-    ( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG >> 0 ) & 0xFF,
-    ( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG >> 16 ) & 0xFF,
-    ( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG >>  8 ) & 0xFF,
-    ( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG >>  0 ) & 0xFF,
+    MBEDTLS_BYTE_1( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
+    MBEDTLS_BYTE_0( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
+    MBEDTLS_BYTE_2( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG ),
+    MBEDTLS_BYTE_1( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG ),
+    MBEDTLS_BYTE_0( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG ),
 };
 
 /*
@@ -5595,10 +5701,8 @@
     used += 4 + session_len;
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( session_len >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( session_len >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( session_len >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( session_len       ) & 0xFF );
+        MBEDTLS_PUT_UINT32_BE( session_len, p, 0 );
+        p += 4;
 
         ret = ssl_session_save( ssl->session, 1,
                                 p, session_len, &session_len );
@@ -5639,33 +5743,19 @@
     used += 4;
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( ssl->badmac_seen >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->badmac_seen >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->badmac_seen >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->badmac_seen       ) & 0xFF );
+        MBEDTLS_PUT_UINT32_BE( ssl->badmac_seen, p, 0 );
+        p += 4;
     }
 
 #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
     used += 16;
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( ssl->in_window_top >> 56 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window_top >> 48 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window_top >> 40 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window_top >> 32 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window_top >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window_top >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window_top >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window_top       ) & 0xFF );
+        MBEDTLS_PUT_UINT64_BE( ssl->in_window_top, p, 0 );
+        p += 8;
 
-        *p++ = (unsigned char)( ( ssl->in_window >> 56 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window >> 48 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window >> 40 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window >> 32 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window       ) & 0xFF );
+        MBEDTLS_PUT_UINT64_BE( ssl->in_window, p, 0 );
+        p += 8;
     }
 #endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */
 
@@ -5688,8 +5778,8 @@
     used += 2;
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( ssl->mtu >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->mtu       ) & 0xFF );
+        MBEDTLS_PUT_UINT16_BE( ssl->mtu, p, 0 );
+        p += 2;
     }
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
 
@@ -5853,14 +5943,14 @@
     if( (size_t)( end - p ) < sizeof( ssl->transform->randbytes ) )
         return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
 
-    ret = ssl_populate_transform( ssl->transform,
+    ret = ssl_tls12_populate_transform( ssl->transform,
                   ssl->session->ciphersuite,
                   ssl->session->master,
-#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
-#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
+#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC) && \
+    defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
                   ssl->session->encrypt_then_mac,
-#endif
-#endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */
+#endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC &&
+          MBEDTLS_SSL_SOME_SUITES_USE_MAC */
                   ssl_tls12prf_from_cs( ssl->session->ciphersuite ),
                   p, /* currently pointing to randbytes */
                   MBEDTLS_SSL_MINOR_VERSION_3, /* (D)TLS 1.2 is forced */
@@ -6091,6 +6181,11 @@
         mbedtls_free( ssl->session_negotiate );
     }
 
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+    mbedtls_ssl_transform_free( ssl->transform_application );
+    mbedtls_free( ssl->transform_application );
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
+
     if( ssl->session )
     {
         mbedtls_ssl_session_free( ssl->session );
@@ -6191,6 +6286,37 @@
     MBEDTLS_MD_SHA384,
     MBEDTLS_MD_NONE
 };
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+static uint16_t ssl_preset_default_sig_algs[] = {
+    /* ECDSA algorithms */
+#if defined(MBEDTLS_ECDSA_C)
+#if defined(MBEDTLS_SHA256_C) && defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED)
+    MBEDTLS_TLS13_SIG_ECDSA_SECP256R1_SHA256,
+#endif /* MBEDTLS_SHA256_C && MBEDTLS_ECP_DP_SECP256R1_ENABLED */
+#if defined(MBEDTLS_SHA512_C) && defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED)
+    MBEDTLS_TLS13_SIG_ECDSA_SECP384R1_SHA384,
+#endif /* MBEDTLS_SHA512_C && MBEDTLS_ECP_DP_SECP384R1_ENABLED */
+#if defined(MBEDTLS_SHA512_C) && defined(MBEDTLS_ECP_DP_SECP521R1_ENABLED)
+    MBEDTLS_TLS13_SIG_ECDSA_SECP521R1_SHA512,
+#endif /* MBEDTLS_SHA512_C && MBEDTLS_ECP_DP_SECP521R1_ENABLED */
+#endif /* MBEDTLS_ECDSA_C */
+    MBEDTLS_TLS13_SIG_NONE
+};
+
+static uint16_t ssl_preset_suiteb_sig_algs[] = {
+    /* ECDSA algorithms */
+#if defined(MBEDTLS_ECDSA_C)
+#if defined(MBEDTLS_SHA256_C) && defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED)
+    MBEDTLS_TLS13_SIG_ECDSA_SECP256R1_SHA256,
+#endif /* MBEDTLS_SHA256_C && MBEDTLS_ECP_DP_SECP256R1_ENABLED */
+#if defined(MBEDTLS_SHA512_C) && defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED)
+    MBEDTLS_TLS13_SIG_ECDSA_SECP384R1_SHA384,
+#endif /* MBEDTLS_SHA512_C && MBEDTLS_ECP_DP_SECP384R1_ENABLED */
+#endif /* MBEDTLS_ECDSA_C */
+    MBEDTLS_TLS13_SIG_NONE
+};
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
 #endif
 
 #if defined(MBEDTLS_ECP_C)
@@ -6305,6 +6431,9 @@
 
 #if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
             conf->sig_hashes = ssl_preset_suiteb_hashes;
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+            conf->tls13_sig_algs = ssl_preset_suiteb_sig_algs;
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
 #endif
 
 #if defined(MBEDTLS_ECP_C)
@@ -6339,7 +6468,10 @@
 
 #if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
             conf->sig_hashes = ssl_preset_default_hashes;
-#endif
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+            conf->tls13_sig_algs = ssl_preset_default_sig_algs;
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
+#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
 
 #if defined(MBEDTLS_ECP_C)
             conf->curve_list = ssl_preset_default_curves;
diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
new file mode 100644
index 0000000..368b557
--- /dev/null
+++ b/library/ssl_tls13_client.c
@@ -0,0 +1,38 @@
+/*
+ *  TLS 1.3 client-side functions
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of mbed TLS ( https://tls.mbed.org )
+ */
+
+#include "common.h"
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+
+#if defined(MBEDTLS_SSL_CLI_C)
+
+#include "ssl_misc.h"
+
+int mbedtls_ssl_handshake_client_step_tls1_3( mbedtls_ssl_context *ssl )
+{
+    ((void) ssl);
+    return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+}
+
+#endif /* MBEDTLS_SSL_CLI_C */
+
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
diff --git a/library/ssl_tls13_keys.c b/library/ssl_tls13_keys.c
index f1c8a12..7aec21d 100644
--- a/library/ssl_tls13_keys.c
+++ b/library/ssl_tls13_keys.c
@@ -113,17 +113,17 @@
 #endif
 
     *p++ = 0;
-    *p++ = (unsigned char)( ( desired_length >> 0 ) & 0xFF );
+    *p++ = MBEDTLS_BYTE_0( desired_length );
 
     /* Add label incl. prefix */
-    *p++ = (unsigned char)( total_label_len & 0xFF );
+    *p++ = MBEDTLS_BYTE_0( total_label_len );
     memcpy( p, tls1_3_label_prefix, sizeof(tls1_3_label_prefix) );
     p += sizeof(tls1_3_label_prefix);
     memcpy( p, label, llen );
     p += llen;
 
     /* Add context value */
-    *p++ = (unsigned char)( clen & 0xFF );
+    *p++ = MBEDTLS_BYTE_0( clen );
     if( clen != 0 )
         memcpy( p, ctx, clen );
 
@@ -699,4 +699,125 @@
     return( ret );
 }
 
+int mbedtls_ssl_tls13_populate_transform( mbedtls_ssl_transform *transform,
+                                          int endpoint,
+                                          int ciphersuite,
+                                          mbedtls_ssl_key_set const *traffic_keys,
+                                          mbedtls_ssl_context *ssl /* DEBUG ONLY */ )
+{
+    int ret;
+    mbedtls_cipher_info_t const *cipher_info;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
+    unsigned char const *key_enc;
+    unsigned char const *iv_enc;
+    unsigned char const *key_dec;
+    unsigned char const *iv_dec;
+
+#if !defined(MBEDTLS_DEBUG_C)
+    ssl = NULL; /* make sure we don't use it except for those cases */
+    (void) ssl;
+#endif
+
+    ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( ciphersuite );
+    if( ciphersuite_info == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "ciphersuite info for %d not found",
+                                    ciphersuite ) );
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    cipher_info = mbedtls_cipher_info_from_type( ciphersuite_info->cipher );
+    if( cipher_info == NULL )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "cipher info for %u not found",
+                                    ciphersuite_info->cipher ) );
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+
+    /*
+     * Setup cipher contexts in target transform
+     */
+
+    if( ( ret = mbedtls_cipher_setup( &transform->cipher_ctx_enc,
+                                      cipher_info ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setup", ret );
+        return( ret );
+    }
+
+    if( ( ret = mbedtls_cipher_setup( &transform->cipher_ctx_dec,
+                                      cipher_info ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setup", ret );
+        return( ret );
+    }
+
+#if defined(MBEDTLS_SSL_SRV_C)
+    if( endpoint == MBEDTLS_SSL_IS_SERVER )
+    {
+        key_enc = traffic_keys->server_write_key;
+        key_dec = traffic_keys->client_write_key;
+        iv_enc = traffic_keys->server_write_iv;
+        iv_dec = traffic_keys->client_write_iv;
+    }
+    else
+#endif /* MBEDTLS_SSL_SRV_C */
+#if defined(MBEDTLS_SSL_CLI_C)
+    if( endpoint == MBEDTLS_SSL_IS_CLIENT )
+    {
+        key_enc = traffic_keys->client_write_key;
+        key_dec = traffic_keys->server_write_key;
+        iv_enc = traffic_keys->client_write_iv;
+        iv_dec = traffic_keys->server_write_iv;
+    }
+    else
+#endif /* MBEDTLS_SSL_CLI_C */
+    {
+        /* should not happen */
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    memcpy( transform->iv_enc, iv_enc, traffic_keys->iv_len );
+    memcpy( transform->iv_dec, iv_dec, traffic_keys->iv_len );
+
+    if( ( ret = mbedtls_cipher_setkey( &transform->cipher_ctx_enc,
+                                       key_enc, cipher_info->key_bitlen,
+                                       MBEDTLS_ENCRYPT ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setkey", ret );
+        return( ret );
+    }
+
+    if( ( ret = mbedtls_cipher_setkey( &transform->cipher_ctx_dec,
+                                       key_dec, cipher_info->key_bitlen,
+                                       MBEDTLS_DECRYPT ) ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_setkey", ret );
+        return( ret );
+    }
+
+    /*
+     * Setup other fields in SSL transform
+     */
+
+    if( ( ciphersuite_info->flags & MBEDTLS_CIPHERSUITE_SHORT_TAG ) != 0 )
+        transform->taglen  = 8;
+    else
+        transform->taglen  = 16;
+
+    transform->ivlen       = traffic_keys->iv_len;
+    transform->maclen      = 0;
+    transform->fixed_ivlen = transform->ivlen;
+    transform->minor_ver   = MBEDTLS_SSL_MINOR_VERSION_4;
+
+    /* We add the true record content type (1 Byte) to the plaintext and
+     * then pad to the configured granularity. The mimimum length of the
+     * type-extended and padded plaintext is therefore the padding
+     * granularity. */
+    transform->minlen =
+        transform->taglen + MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY;
+
+    return( 0 );
+}
+
 #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
diff --git a/library/ssl_tls13_keys.h b/library/ssl_tls13_keys.h
index 3b96998..ca892b1 100644
--- a/library/ssl_tls13_keys.h
+++ b/library/ssl_tls13_keys.h
@@ -498,4 +498,37 @@
                                unsigned char const *transcript,
                                unsigned char *result );
 
+/**
+ * \bref Setup an SSL transform structure representing the
+ *       record protection mechanism used by TLS 1.3
+ *
+ * \param transform    The SSL transform structure to be created. This must have
+ *                     been initialized through mbedtls_ssl_transform_init() and
+ *                     not used in any other way prior to calling this function.
+ *                     In particular, this function does not clean up the
+ *                     transform structure prior to installing the new keys.
+ * \param endpoint     Indicates whether the transform is for the client
+ *                     (value #MBEDTLS_SSL_IS_CLIENT) or the server
+ *                     (value #MBEDTLS_SSL_IS_SERVER).
+ * \param ciphersuite  The numerical identifier for the ciphersuite to use.
+ *                     This must be one of the identifiers listed in
+ *                     ssl_ciphersuites.h.
+ * \param traffic_keys The key material to use. No reference is stored in
+ *                     the SSL transform being generated, and the caller
+ *                     should destroy the key material afterwards.
+ * \param ssl          (Debug-only) The SSL context to use for debug output
+ *                     in case of failure. This parameter is only needed if
+ *                     #MBEDTLS_DEBUG_C is set, and is ignored otherwise.
+ *
+ * \return             \c 0 on success. In this case, \p transform is ready to
+ *                     be used with mbedtls_ssl_transform_decrypt() and
+ *                     mbedtls_ssl_transform_encrypt().
+ * \return             A negative error code on failure.
+ */
+int mbedtls_ssl_tls13_populate_transform( mbedtls_ssl_transform *transform,
+                                          int endpoint,
+                                          int ciphersuite,
+                                          mbedtls_ssl_key_set const *traffic_keys,
+                                          mbedtls_ssl_context *ssl );
+
 #endif /* MBEDTLS_SSL_TLS1_3_KEYS_H */
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
new file mode 100644
index 0000000..a567277
--- /dev/null
+++ b/library/ssl_tls13_server.c
@@ -0,0 +1,36 @@
+/*
+ *  TLS 1.3 server-side functions
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+*/
+
+#include "common.h"
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+
+#if defined(MBEDTLS_SSL_SRV_C)
+
+#include "ssl_misc.h"
+
+int mbedtls_ssl_handshake_server_step_tls1_3( mbedtls_ssl_context *ssl )
+{
+    ((void) ssl);
+    return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+}
+
+#endif /* MBEDTLS_SSL_SRV_C */
+
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
diff --git a/library/x509write_crt.c b/library/x509write_crt.c
index c8169f1..17b3e79 100644
--- a/library/x509write_crt.c
+++ b/library/x509write_crt.c
@@ -251,8 +251,7 @@
         return( MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE );
 
     c = buf + 5;
-    ku[0] = (unsigned char)( key_usage      );
-    ku[1] = (unsigned char)( key_usage >> 8 );
+    MBEDTLS_PUT_UINT16_LE( key_usage, ku, 0 );
     ret = mbedtls_asn1_write_named_bitstring( &c, buf, ku, 9 );
 
     if( ret < 0 )