Put local variables in a struct
This way we can have a single call to mbedtls_platform_zeroize, which
saves a few bytes of code size.
Additionally, on my PC, I notice a significant speed improvement
(x86_64 build with MBEDTLS_AESNI_C disabled, gcc 5.4.0 -O3). I don't
have an explanation for that (I expected no measurable difference).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/aes.c b/library/aes.c
index 132849d..183cedc 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -897,61 +897,56 @@
unsigned char output[16] )
{
int i;
- uint32_t *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3;
+ uint32_t *RK = ctx->rk;
+ struct
+ {
+ uint32_t X[4];
+ uint32_t Y[4];
+ } t;
- RK = ctx->rk;
-
- GET_UINT32_LE( X0, input, 0 ); X0 ^= *RK++;
- GET_UINT32_LE( X1, input, 4 ); X1 ^= *RK++;
- GET_UINT32_LE( X2, input, 8 ); X2 ^= *RK++;
- GET_UINT32_LE( X3, input, 12 ); X3 ^= *RK++;
+ 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++;
for( i = ( ctx->nr >> 1 ) - 1; i > 0; i-- )
{
- AES_FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
- AES_FROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );
+ 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] );
+ AES_FROUND( t.X[0], t.X[1], t.X[2], t.X[3], t.Y[0], t.Y[1], t.Y[2], t.Y[3] );
}
- AES_FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
+ 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] );
- X0 = *RK++ ^ \
- ( (uint32_t) FSb[ ( Y0 ) & 0xFF ] ) ^
- ( (uint32_t) FSb[ ( Y1 >> 8 ) & 0xFF ] << 8 ) ^
- ( (uint32_t) FSb[ ( Y2 >> 16 ) & 0xFF ] << 16 ) ^
- ( (uint32_t) FSb[ ( Y3 >> 24 ) & 0xFF ] << 24 );
+ 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 );
- X1 = *RK++ ^ \
- ( (uint32_t) FSb[ ( Y1 ) & 0xFF ] ) ^
- ( (uint32_t) FSb[ ( Y2 >> 8 ) & 0xFF ] << 8 ) ^
- ( (uint32_t) FSb[ ( Y3 >> 16 ) & 0xFF ] << 16 ) ^
- ( (uint32_t) FSb[ ( Y0 >> 24 ) & 0xFF ] << 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 );
- X2 = *RK++ ^ \
- ( (uint32_t) FSb[ ( Y2 ) & 0xFF ] ) ^
- ( (uint32_t) FSb[ ( Y3 >> 8 ) & 0xFF ] << 8 ) ^
- ( (uint32_t) FSb[ ( Y0 >> 16 ) & 0xFF ] << 16 ) ^
- ( (uint32_t) FSb[ ( Y1 >> 24 ) & 0xFF ] << 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 );
- X3 = *RK++ ^ \
- ( (uint32_t) FSb[ ( Y3 ) & 0xFF ] ) ^
- ( (uint32_t) FSb[ ( Y0 >> 8 ) & 0xFF ] << 8 ) ^
- ( (uint32_t) FSb[ ( Y1 >> 16 ) & 0xFF ] << 16 ) ^
- ( (uint32_t) FSb[ ( Y2 >> 24 ) & 0xFF ] << 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 );
- PUT_UINT32_LE( X0, output, 0 );
- PUT_UINT32_LE( X1, output, 4 );
- PUT_UINT32_LE( X2, output, 8 );
- PUT_UINT32_LE( X3, output, 12 );
+ 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_platform_zeroize( &X0, sizeof( X0 ) );
- mbedtls_platform_zeroize( &X1, sizeof( X1 ) );
- mbedtls_platform_zeroize( &X2, sizeof( X2 ) );
- mbedtls_platform_zeroize( &X3, sizeof( X3 ) );
-
- mbedtls_platform_zeroize( &Y0, sizeof( Y0 ) );
- mbedtls_platform_zeroize( &Y1, sizeof( Y1 ) );
- mbedtls_platform_zeroize( &Y2, sizeof( Y2 ) );
- mbedtls_platform_zeroize( &Y3, sizeof( Y3 ) );
+ mbedtls_platform_zeroize( &t, sizeof( t ) );
return( 0 );
}
@@ -975,61 +970,56 @@
unsigned char output[16] )
{
int i;
- uint32_t *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3;
+ uint32_t *RK = ctx->rk;
+ struct
+ {
+ uint32_t X[4];
+ uint32_t Y[4];
+ } t;
- RK = ctx->rk;
-
- GET_UINT32_LE( X0, input, 0 ); X0 ^= *RK++;
- GET_UINT32_LE( X1, input, 4 ); X1 ^= *RK++;
- GET_UINT32_LE( X2, input, 8 ); X2 ^= *RK++;
- GET_UINT32_LE( X3, input, 12 ); X3 ^= *RK++;
+ 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++;
for( i = ( ctx->nr >> 1 ) - 1; i > 0; i-- )
{
- AES_RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
- AES_RROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );
+ 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] );
+ AES_RROUND( t.X[0], t.X[1], t.X[2], t.X[3], t.Y[0], t.Y[1], t.Y[2], t.Y[3] );
}
- AES_RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );
+ 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] );
- X0 = *RK++ ^ \
- ( (uint32_t) RSb[ ( Y0 ) & 0xFF ] ) ^
- ( (uint32_t) RSb[ ( Y3 >> 8 ) & 0xFF ] << 8 ) ^
- ( (uint32_t) RSb[ ( Y2 >> 16 ) & 0xFF ] << 16 ) ^
- ( (uint32_t) RSb[ ( Y1 >> 24 ) & 0xFF ] << 24 );
+ 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 );
- X1 = *RK++ ^ \
- ( (uint32_t) RSb[ ( Y1 ) & 0xFF ] ) ^
- ( (uint32_t) RSb[ ( Y0 >> 8 ) & 0xFF ] << 8 ) ^
- ( (uint32_t) RSb[ ( Y3 >> 16 ) & 0xFF ] << 16 ) ^
- ( (uint32_t) RSb[ ( Y2 >> 24 ) & 0xFF ] << 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 );
- X2 = *RK++ ^ \
- ( (uint32_t) RSb[ ( Y2 ) & 0xFF ] ) ^
- ( (uint32_t) RSb[ ( Y1 >> 8 ) & 0xFF ] << 8 ) ^
- ( (uint32_t) RSb[ ( Y0 >> 16 ) & 0xFF ] << 16 ) ^
- ( (uint32_t) RSb[ ( Y3 >> 24 ) & 0xFF ] << 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 );
- X3 = *RK++ ^ \
- ( (uint32_t) RSb[ ( Y3 ) & 0xFF ] ) ^
- ( (uint32_t) RSb[ ( Y2 >> 8 ) & 0xFF ] << 8 ) ^
- ( (uint32_t) RSb[ ( Y1 >> 16 ) & 0xFF ] << 16 ) ^
- ( (uint32_t) RSb[ ( Y0 >> 24 ) & 0xFF ] << 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 );
- PUT_UINT32_LE( X0, output, 0 );
- PUT_UINT32_LE( X1, output, 4 );
- PUT_UINT32_LE( X2, output, 8 );
- PUT_UINT32_LE( X3, output, 12 );
+ 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_platform_zeroize( &X0, sizeof( X0 ) );
- mbedtls_platform_zeroize( &X1, sizeof( X1 ) );
- mbedtls_platform_zeroize( &X2, sizeof( X2 ) );
- mbedtls_platform_zeroize( &X3, sizeof( X3 ) );
-
- mbedtls_platform_zeroize( &Y0, sizeof( Y0 ) );
- mbedtls_platform_zeroize( &Y1, sizeof( Y1 ) );
- mbedtls_platform_zeroize( &Y2, sizeof( Y2 ) );
- mbedtls_platform_zeroize( &Y3, sizeof( Y3 ) );
+ mbedtls_platform_zeroize( &t, sizeof( t ) );
return( 0 );
}