133 lines
3.5 KiB
C
133 lines
3.5 KiB
C
/* blake2-keyed-mac.c
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*
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* Copyright (C) 2006-2026 wolfSSL Inc.
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*
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* This file is part of wolfSSL. (formerly known as CyaSSL)
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*
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* wolfSSL is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* wolfSSL is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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/* Example of BLAKE2b in keyed mode, used as a MAC.
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*
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* BLAKE2's native keyed mode replaces the HMAC construction: the key is mixed
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* into the initial state, so a single hash pass produces the tag. */
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#include <stdio.h>
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#include <string.h>
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#include <wolfssl/options.h>
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#include <wolfssl/wolfcrypt/settings.h>
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#include <wolfssl/wolfcrypt/blake2.h>
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#include <wolfssl/wolfcrypt/random.h>
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#ifdef HAVE_BLAKE2B
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/* 32-byte tag is plenty for a MAC; BLAKE2b allows 1-64. */
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#define TAG_SZ 32
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#define KEY_SZ 32
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static void print_hex(const char* label, const byte* data, word32 len)
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{
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word32 i;
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printf("%s: ", label);
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for (i = 0; i < len; i++)
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printf("%02x", data[i]);
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printf("\n");
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}
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static int mac_message(const byte* key, word32 keySz, const char* msg,
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byte* tag, word32 tagSz)
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{
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int ret;
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Blake2b b2b;
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ret = wc_InitBlake2b_WithKey(&b2b, tagSz, key, keySz);
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if (ret == 0)
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ret = wc_Blake2bUpdate(&b2b, (const byte*)msg, (word32)strlen(msg));
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if (ret == 0)
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ret = wc_Blake2bFinal(&b2b, tag, tagSz);
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return ret;
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}
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int main(void)
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{
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int ret;
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WC_RNG rng;
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byte key[KEY_SZ];
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byte tag[TAG_SZ];
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byte check[TAG_SZ];
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const char* msg = "authenticate this message";
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ret = wc_InitRng(&rng);
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if (ret != 0) {
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printf("wc_InitRng failed %d\n", ret);
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return 1;
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}
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ret = wc_RNG_GenerateBlock(&rng, key, KEY_SZ);
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wc_FreeRng(&rng);
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if (ret != 0) {
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printf("wc_RNG_GenerateBlock failed %d\n", ret);
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return 1;
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}
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ret = mac_message(key, KEY_SZ, msg, tag, TAG_SZ);
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if (ret != 0) {
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printf("MAC generation failed %d\n", ret);
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return 1;
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}
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print_hex("key", key, KEY_SZ);
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print_hex("tag", tag, TAG_SZ);
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/* Verifier recomputes the tag with the shared key and compares. */
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ret = mac_message(key, KEY_SZ, msg, check, TAG_SZ);
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if (ret != 0) {
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printf("MAC verification failed %d\n", ret);
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return 1;
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}
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if (memcmp(tag, check, TAG_SZ) != 0) {
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printf("MAC mismatch!\n");
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return 1;
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}
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printf("MAC verified\n");
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/* A different key must produce a different tag. */
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key[0] ^= 0x01;
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ret = mac_message(key, KEY_SZ, msg, check, TAG_SZ);
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if (ret != 0) {
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printf("MAC computation failed %d\n", ret);
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return 1;
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}
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if (memcmp(tag, check, TAG_SZ) == 0) {
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printf("Tag did not change with key!\n");
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return 1;
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}
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printf("Wrong key rejected\n");
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return 0;
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}
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#else
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int main(void)
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{
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printf("Please build wolfSSL with ./configure --enable-blake2\n");
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return 0;
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}
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#endif /* HAVE_BLAKE2B */
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