Move mbedtls_cf_memcmp to a new public header

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>

include/mbedtls/constant_time.h

@@ -0,0 +1,47 @@
+/**
+ *  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.
+ */
+
+#ifndef MBEDTLS_CONSTANT_TIME_H
+#define MBEDTLS_CONSTANT_TIME_H
+
+#include "common.h"
+
+#include <stddef.h>
+
+
+/** Constant-time buffer comparison without branches.
+ *
+ * This is equivalent to the standard memncmp function, but is likely to be
+ * compiled to code using bitwise operation rather than a branch.
+ *
+ * This function can be used to write constant-time code by replacing branches
+ * with bit operations using masks.
+ *
+ * \param a     Pointer to the first buffer.
+ * \param b     Pointer to the second buffer.
+ * \param n     The number of bytes to compare in the buffer.
+ *
+ * \return      Zero if the content of the two buffer is the same,
+ *              otherwise non-zero.
+ */
+int mbedtls_cf_memcmp( const void *a,
+                       const void *b,
+                       size_t n );
+
+#endif /* MBEDTLS_CONSTANT_TIME_H */

library/cipher.c

@@ -29,7 +29,7 @@
 #include "mbedtls/cipher_internal.h"
 #include "mbedtls/platform_util.h"
 #include "mbedtls/error.h"
-#include "constant_time.h"
+#include "mbedtls/constant_time.h"
 
 #include <stdlib.h>
 #include <string.h>

library/constant_time.c

@@ -24,6 +24,7 @@
 
 #include "common.h"
 #include "constant_time.h"
+#include "mbedtls/constant_time.h"
 #include "mbedtls/error.h"
 #include "mbedtls/platform_util.h"
 

library/constant_time.h

@@ -33,25 +33,6 @@
 #include <stddef.h>
 
 
-/** Constant-time buffer comparison without branches.
- *
- * This is equivalent to the standard memncmp function, but is likely to be
- * compiled to code using bitwise operation rather than a branch.
- *
- * This function can be used to write constant-time code by replacing branches
- * with bit operations using masks.
- *
- * \param a     Pointer to the first buffer.
- * \param b     Pointer to the second buffer.
- * \param n     The number of bytes to compare in the buffer.
- *
- * \return      Zero if the content of the two buffer is the same,
- *              otherwise non-zero.
- */
-int mbedtls_cf_memcmp( const void *a,
-                       const void *b,
-                       size_t n );
-
 /** Turn a value into a mask:
  * - if \p value == 0, return the all-bits 0 mask, aka 0
  * - otherwise, return the all-bits 1 mask, aka (unsigned) -1

library/nist_kw.c

@@ -34,7 +34,7 @@
 #include "mbedtls/nist_kw.h"
 #include "mbedtls/platform_util.h"
 #include "mbedtls/error.h"
-#include "constant_time.h"
+#include "mbedtls/constant_time.h"
 
 #include <stdint.h>
 #include <string.h>

library/rsa.c

@@ -45,6 +45,7 @@
 #include "mbedtls/platform_util.h"
 #include "mbedtls/error.h"
 #include "constant_time.h"
+#include "mbedtls/constant_time.h"
 
 #include <string.h>
 

library/ssl_cli.c

@@ -33,7 +33,7 @@
 #include "mbedtls/ssl_internal.h"
 #include "mbedtls/debug.h"
 #include "mbedtls/error.h"
-#include "constant_time.h"
+#include "mbedtls/constant_time.h"
 
 #if defined(MBEDTLS_USE_PSA_CRYPTO)
 #include "mbedtls/psa_util.h"

library/ssl_cookie.c

@@ -36,7 +36,7 @@
 #include "mbedtls/ssl_internal.h"
 #include "mbedtls/error.h"
 #include "mbedtls/platform_util.h"
-#include "constant_time.h"
+#include "mbedtls/constant_time.h"
 
 #include <string.h>
 

library/ssl_msg.c

@@ -45,6 +45,7 @@
 #include "mbedtls/platform_util.h"
 #include "mbedtls/version.h"
 #include "constant_time.h"
+#include "mbedtls/constant_time.h"
 
 #include <string.h>
 

library/ssl_srv.c

@@ -35,6 +35,7 @@
 #include "mbedtls/error.h"
 #include "mbedtls/platform_util.h"
 #include "constant_time.h"
+#include "mbedtls/constant_time.h"
 
 #include <string.h>
 

library/ssl_tls.c

@@ -43,7 +43,7 @@
 #include "mbedtls/error.h"
 #include "mbedtls/platform_util.h"
 #include "mbedtls/version.h"
-#include "constant_time.h"
+#include "mbedtls/constant_time.h"
 
 #include <string.h>