diff --git a/library/cipher.c b/library/cipher.c
index b956030..1472413 100644
--- a/library/cipher.c
+++ b/library/cipher.c
@@ -29,6 +29,7 @@
 #include "mbedtls/cipher_internal.h"
 #include "mbedtls/platform_util.h"
 #include "mbedtls/error.h"
+#include "constant_time.h"
 
 #include <stdlib.h>
 #include <string.h>
@@ -74,27 +75,6 @@
 #define CIPHER_VALIDATE( cond )        \
     MBEDTLS_INTERNAL_VALIDATE( cond )
 
-#if defined(MBEDTLS_GCM_C) || defined(MBEDTLS_CHACHAPOLY_C)
-/* Compare the contents of two buffers in constant time.
- * Returns 0 if the contents are bitwise identical, otherwise returns
- * a non-zero value.
- * This is currently only used by GCM and ChaCha20+Poly1305.
- */
-static int mbedtls_constant_time_memcmp( const void *v1, const void *v2,
-                                         size_t len )
-{
-    const unsigned char *p1 = (const unsigned char*) v1;
-    const unsigned char *p2 = (const unsigned char*) v2;
-    size_t i;
-    unsigned char diff;
-
-    for( diff = 0, i = 0; i < len; i++ )
-        diff |= p1[i] ^ p2[i];
-
-    return( (int)diff );
-}
-#endif /* MBEDTLS_GCM_C || MBEDTLS_CHACHAPOLY_C */
-
 static int supported_init = 0;
 
 const int *mbedtls_cipher_list( void )
diff --git a/library/constant_time.c b/library/constant_time.c
index 9f0229b..cb156bc 100644
--- a/library/constant_time.c
+++ b/library/constant_time.c
@@ -18,3 +18,77 @@
  */
 
 #include "common.h"
+#include "constant_time.h"
+
+/* constant-time buffer comparison */
+int mbedtls_ssl_safer_memcmp( const void *a, const void *b, size_t n )
+{
+    size_t i;
+    volatile const unsigned char *A = (volatile const unsigned char *) a;
+    volatile const unsigned char *B = (volatile const unsigned char *) b;
+    volatile unsigned char diff = 0;
+
+    for( i = 0; i < n; i++ )
+    {
+        /* Read volatile data in order before computing diff.
+         * This avoids IAR compiler warning:
+         * 'the order of volatile accesses is undefined ..' */
+        unsigned char x = A[i], y = B[i];
+        diff |= x ^ y;
+    }
+
+    return( diff );
+}
+
+/* Compare the contents of two buffers in constant time.
+ * Returns 0 if the contents are bitwise identical, otherwise returns
+ * a non-zero value.
+ * This is currently only used by GCM and ChaCha20+Poly1305.
+ */
+int mbedtls_constant_time_memcmp( const void *v1, const void *v2,
+                                  size_t len )
+{
+    const unsigned char *p1 = (const unsigned char*) v1;
+    const unsigned char *p2 = (const unsigned char*) v2;
+    size_t i;
+    unsigned char diff;
+
+    for( diff = 0, i = 0; i < len; i++ )
+        diff |= p1[i] ^ p2[i];
+
+    return( (int)diff );
+}
+
+/* constant-time buffer comparison */
+unsigned char mbedtls_nist_kw_safer_memcmp( const void *a, const void *b, size_t n )
+{
+    size_t i;
+    volatile const unsigned char *A = (volatile const unsigned char *) a;
+    volatile const unsigned char *B = (volatile const unsigned char *) b;
+    volatile unsigned char diff = 0;
+
+    for( i = 0; i < n; i++ )
+    {
+        /* Read volatile data in order before computing diff.
+         * This avoids IAR compiler warning:
+         * 'the order of volatile accesses is undefined ..' */
+        unsigned char x = A[i], y = B[i];
+        diff |= x ^ y;
+    }
+
+    return( diff );
+}
+
+/* constant-time buffer comparison */
+int mbedtls_safer_memcmp( const void *a, const void *b, size_t n )
+{
+    size_t i;
+    const unsigned char *A = (const unsigned char *) a;
+    const unsigned char *B = (const unsigned char *) b;
+    unsigned char diff = 0;
+
+    for( i = 0; i < n; i++ )
+        diff |= A[i] ^ B[i];
+
+    return( diff );
+}
diff --git a/library/constant_time.h b/library/constant_time.h
new file mode 100644
index 0000000..e14232b
--- /dev/null
+++ b/library/constant_time.h
@@ -0,0 +1,30 @@
+/**
+ *  Constant-time 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"
+
+#include <stddef.h>
+
+int mbedtls_ssl_safer_memcmp( const void *a, const void *b, size_t n );
+
+int mbedtls_constant_time_memcmp( const void *v1, const void *v2, size_t len );
+
+unsigned char mbedtls_nist_kw_safer_memcmp( const void *a, const void *b, size_t n );
+
+int mbedtls_safer_memcmp( const void *a, const void *b, size_t n );
diff --git a/library/nist_kw.c b/library/nist_kw.c
index e2ab256..6262a7b 100644
--- a/library/nist_kw.c
+++ b/library/nist_kw.c
@@ -34,6 +34,7 @@
 #include "mbedtls/nist_kw.h"
 #include "mbedtls/platform_util.h"
 #include "mbedtls/error.h"
+#include "constant_time.h"
 
 #include <stdint.h>
 #include <string.h>
@@ -52,26 +53,6 @@
 #define KW_SEMIBLOCK_LENGTH    8
 #define MIN_SEMIBLOCKS_COUNT   3
 
-/* constant-time buffer comparison */
-static inline unsigned char mbedtls_nist_kw_safer_memcmp( const void *a, const void *b, size_t n )
-{
-    size_t i;
-    volatile const unsigned char *A = (volatile const unsigned char *) a;
-    volatile const unsigned char *B = (volatile const unsigned char *) b;
-    volatile unsigned char diff = 0;
-
-    for( i = 0; i < n; i++ )
-    {
-        /* Read volatile data in order before computing diff.
-         * This avoids IAR compiler warning:
-         * 'the order of volatile accesses is undefined ..' */
-        unsigned char x = A[i], y = B[i];
-        diff |= x ^ y;
-    }
-
-    return( diff );
-}
-
 /*! The 64-bit default integrity check value (ICV) for KW mode. */
 static const unsigned char NIST_KW_ICV1[] = {0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6};
 /*! The 32-bit default integrity check value (ICV) for KWP mode. */
diff --git a/library/rsa.c b/library/rsa.c
index 02b40d0..06653a5 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -44,6 +44,7 @@
 #include "mbedtls/oid.h"
 #include "mbedtls/platform_util.h"
 #include "mbedtls/error.h"
+#include "constant_time.h"
 
 #include <string.h>
 
@@ -72,22 +73,6 @@
 #define RSA_VALIDATE( cond )                                           \
     MBEDTLS_INTERNAL_VALIDATE( cond )
 
-#if defined(MBEDTLS_PKCS1_V15)
-/* constant-time buffer comparison */
-static inline int mbedtls_safer_memcmp( const void *a, const void *b, size_t n )
-{
-    size_t i;
-    const unsigned char *A = (const unsigned char *) a;
-    const unsigned char *B = (const unsigned char *) b;
-    unsigned char diff = 0;
-
-    for( i = 0; i < n; i++ )
-        diff |= A[i] ^ B[i];
-
-    return( diff );
-}
-#endif /* MBEDTLS_PKCS1_V15 */
-
 int mbedtls_rsa_import( mbedtls_rsa_context *ctx,
                         const mbedtls_mpi *N,
                         const mbedtls_mpi *P, const mbedtls_mpi *Q,
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index b02a3a5..912b5d0 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -33,6 +33,7 @@
 #include "mbedtls/ssl_internal.h"
 #include "mbedtls/debug.h"
 #include "mbedtls/error.h"
+#include "constant_time.h"
 
 #if defined(MBEDTLS_USE_PSA_CRYPTO)
 #include "mbedtls/psa_util.h"
diff --git a/library/ssl_cookie.c b/library/ssl_cookie.c
index 071e55e..84fbab1 100644
--- a/library/ssl_cookie.c
+++ b/library/ssl_cookie.c
@@ -36,6 +36,7 @@
 #include "mbedtls/ssl_internal.h"
 #include "mbedtls/error.h"
 #include "mbedtls/platform_util.h"
+#include "constant_time.h"
 
 #include <string.h>
 
diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index 916456f..b3bd804 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -44,6 +44,7 @@
 #include "mbedtls/error.h"
 #include "mbedtls/platform_util.h"
 #include "mbedtls/version.h"
+#include "constant_time.h"
 
 #include "ssl_invasive.h"
 
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 210e0d3..b9e4bc0 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -34,6 +34,7 @@
 #include "mbedtls/debug.h"
 #include "mbedtls/error.h"
 #include "mbedtls/platform_util.h"
+#include "constant_time.h"
 
 #include <string.h>
 
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 2e9c401..607981a 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -43,6 +43,7 @@
 #include "mbedtls/error.h"
 #include "mbedtls/platform_util.h"
 #include "mbedtls/version.h"
+#include "constant_time.h"
 
 #include <string.h>