From 8d5a38a5f25b56b17b5f6cd1de10afacc792fbee Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Niels=20M=C3=B6ller?= Date: Sat, 14 Mar 2015 07:58:06 +0100 Subject: New function memeql_sec. --- ccm.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) (limited to 'ccm.c') diff --git a/ccm.c b/ccm.c index c5ff7908..b98bc9cf 100644 --- a/ccm.c +++ b/ccm.c @@ -246,6 +246,19 @@ ccm_encrypt_message(const void *cipher, nettle_cipher_func *f, ccm_digest(&ctx, cipher, f, tlength, tag); } +/* FIXME: Should be made public, under some suitable name. */ +static int +memeql_sec (const void *a, const void *b, size_t n) +{ + volatile const unsigned char *ap = (const unsigned char *) a; + volatile const unsigned char *bp = (const unsigned char *) b; + volatile unsigned char d; + size_t i; + for (d = i = 0; i < n; i++) + d |= (ap[i] ^ bp[i]); + return d == 0; +} + int ccm_decrypt_message(const void *cipher, nettle_cipher_func *f, size_t nlength, const uint8_t *nonce, @@ -258,5 +271,5 @@ ccm_decrypt_message(const void *cipher, nettle_cipher_func *f, ccm_update(&ctx, cipher, f, alength, adata); ccm_decrypt(&ctx, cipher, f, mlength, dst, src); ccm_digest(&ctx, cipher, f, tlength, tag); - return (memcmp(tag, src + mlength, tlength) == 0); + return memeql_sec(tag, src + mlength, tlength); } -- cgit v1.2.1