Add and use a constant-time memcmp.

[openssl.git] / crypto / cryptlib.c

diff --git a/crypto/cryptlib.c b/crypto/cryptlib.c
index dd74ea8855f49f988497f7019b1fc5ad911b5524..0566ec1f976a9c3154fe6d129311390c71fd2b83 100644 (file)
--- a/crypto/cryptlib.c
+++ b/crypto/cryptlib.c
@@ -542,3 +542,16 @@ void OpenSSLDie(const char *file,int line,const char *assertion)
        }
 
 void *OPENSSL_stderr(void)     { return stderr; }
+
+int CRYPTO_memcmp(const void *in_a, const void *in_b, size_t len)
+       {
+       size_t i;
+       const unsigned char *a = in_a;
+       const unsigned char *b = in_b;
+       unsigned char x = 0;
+
+       for (i = 0; i < len; i++)
+               x |= a[i] ^ b[i];
+
+       return x;
+       }