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- /* ====================================================================
- * Copyright (c) 2010 The OpenSSL Project. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- *
- * 3. All advertising materials mentioning features or use of this
- * software must display the following acknowledgment:
- * "This product includes software developed by the OpenSSL Project
- * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
- *
- * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
- * endorse or promote products derived from this software without
- * prior written permission. For written permission, please contact
- * licensing@OpenSSL.org.
- *
- * 5. Products derived from this software may not be called "OpenSSL"
- * nor may "OpenSSL" appear in their names without prior written
- * permission of the OpenSSL Project.
- *
- * 6. Redistributions of any form whatsoever must retain the following
- * acknowledgment:
- * "This product includes software developed by the OpenSSL Project
- * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
- *
- * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
- * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
- * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
- * OF THE POSSIBILITY OF SUCH DAMAGE.
- * ==================================================================== */
-
- #include <openssl/cmac.h>
-
- #include <assert.h>
- #include <string.h>
-
- #include <openssl/aes.h>
- #include <openssl/cipher.h>
- #include <openssl/mem.h>
-
-
- struct cmac_ctx_st {
- EVP_CIPHER_CTX cipher_ctx;
- /* k1 and k2 are the CMAC subkeys. See
- * https://tools.ietf.org/html/rfc4493#section-2.3 */
- uint8_t k1[AES_BLOCK_SIZE];
- uint8_t k2[AES_BLOCK_SIZE];
- /* Last (possibly partial) scratch */
- uint8_t block[AES_BLOCK_SIZE];
- /* block_used contains the number of valid bytes in |block|. */
- unsigned block_used;
- };
-
- static void CMAC_CTX_init(CMAC_CTX *ctx) {
- EVP_CIPHER_CTX_init(&ctx->cipher_ctx);
- }
-
- static void CMAC_CTX_cleanup(CMAC_CTX *ctx) {
- EVP_CIPHER_CTX_cleanup(&ctx->cipher_ctx);
- OPENSSL_cleanse(ctx->k1, sizeof(ctx->k1));
- OPENSSL_cleanse(ctx->k2, sizeof(ctx->k2));
- OPENSSL_cleanse(ctx->block, sizeof(ctx->block));
- }
-
- int AES_CMAC(uint8_t out[16], const uint8_t *key, size_t key_len,
- const uint8_t *in, size_t in_len) {
- const EVP_CIPHER *cipher;
- switch (key_len) {
- case 16:
- cipher = EVP_aes_128_cbc();
- break;
- case 32:
- cipher = EVP_aes_256_cbc();
- break;
- default:
- return 0;
- }
-
- size_t scratch_out_len;
- CMAC_CTX ctx;
- CMAC_CTX_init(&ctx);
-
- const int ok = CMAC_Init(&ctx, key, key_len, cipher, NULL /* engine */) &&
- CMAC_Update(&ctx, in, in_len) &&
- CMAC_Final(&ctx, out, &scratch_out_len);
-
- CMAC_CTX_cleanup(&ctx);
- return ok;
- }
-
- CMAC_CTX *CMAC_CTX_new(void) {
- CMAC_CTX *ctx = OPENSSL_malloc(sizeof(*ctx));
- if (ctx != NULL) {
- CMAC_CTX_init(ctx);
- }
- return ctx;
- }
-
- void CMAC_CTX_free(CMAC_CTX *ctx) {
- if (ctx == NULL) {
- return;
- }
-
- CMAC_CTX_cleanup(ctx);
- OPENSSL_free(ctx);
- }
-
- /* binary_field_mul_x treats the 128 bits at |in| as an element of GF(2¹²⁸)
- * with a hard-coded reduction polynomial and sets |out| as x times the
- * input.
- *
- * See https://tools.ietf.org/html/rfc4493#section-2.3 */
- static void binary_field_mul_x(uint8_t out[16], const uint8_t in[16]) {
- unsigned i;
-
- /* Shift |in| to left, including carry. */
- for (i = 0; i < 15; i++) {
- out[i] = (in[i] << 1) | (in[i+1] >> 7);
- }
-
- /* If MSB set fixup with R. */
- const uint8_t carry = in[0] >> 7;
- out[i] = (in[i] << 1) ^ ((0 - carry) & 0x87);
- }
-
- static const uint8_t kZeroIV[AES_BLOCK_SIZE] = {0};
-
- int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t key_len,
- const EVP_CIPHER *cipher, ENGINE *engine) {
- uint8_t scratch[AES_BLOCK_SIZE];
-
- if (EVP_CIPHER_block_size(cipher) != AES_BLOCK_SIZE ||
- EVP_CIPHER_key_length(cipher) != key_len ||
- !EVP_EncryptInit_ex(&ctx->cipher_ctx, cipher, NULL, key, kZeroIV) ||
- !EVP_Cipher(&ctx->cipher_ctx, scratch, kZeroIV, AES_BLOCK_SIZE) ||
- /* Reset context again ready for first data. */
- !EVP_EncryptInit_ex(&ctx->cipher_ctx, NULL, NULL, NULL, kZeroIV)) {
- return 0;
- }
-
- binary_field_mul_x(ctx->k1, scratch);
- binary_field_mul_x(ctx->k2, ctx->k1);
- ctx->block_used = 0;
-
- return 1;
- }
-
- int CMAC_Reset(CMAC_CTX *ctx) {
- ctx->block_used = 0;
- return EVP_EncryptInit_ex(&ctx->cipher_ctx, NULL, NULL, NULL, kZeroIV);
- }
-
- int CMAC_Update(CMAC_CTX *ctx, const uint8_t *in, size_t in_len) {
- uint8_t scratch[AES_BLOCK_SIZE];
-
- if (ctx->block_used > 0) {
- size_t todo = AES_BLOCK_SIZE - ctx->block_used;
- if (in_len < todo) {
- todo = in_len;
- }
-
- memcpy(ctx->block + ctx->block_used, in, todo);
- in += todo;
- in_len -= todo;
- ctx->block_used += todo;
-
- /* If |in_len| is zero then either |ctx->block_used| is less than
- * |AES_BLOCK_SIZE|, in which case we can stop here, or |ctx->block_used|
- * is exactly |AES_BLOCK_SIZE| but there's no more data to process. In the
- * latter case we don't want to process this block now because it might be
- * the last block and that block is treated specially. */
- if (in_len == 0) {
- return 1;
- }
-
- assert(ctx->block_used == AES_BLOCK_SIZE);
-
- if (!EVP_Cipher(&ctx->cipher_ctx, scratch, ctx->block, AES_BLOCK_SIZE)) {
- return 0;
- }
- }
-
- /* Encrypt all but one of the remaining blocks. */
- while (in_len > AES_BLOCK_SIZE) {
- if (!EVP_Cipher(&ctx->cipher_ctx, scratch, in, AES_BLOCK_SIZE)) {
- return 0;
- }
- in += AES_BLOCK_SIZE;
- in_len -= AES_BLOCK_SIZE;
- }
-
- memcpy(ctx->block, in, in_len);
- ctx->block_used = in_len;
-
- return 1;
- }
-
- int CMAC_Final(CMAC_CTX *ctx, uint8_t *out, size_t *out_len) {
- *out_len = AES_BLOCK_SIZE;
- if (out == NULL) {
- return 1;
- }
-
- const uint8_t *mask = ctx->k1;
-
- if (ctx->block_used != AES_BLOCK_SIZE) {
- /* If the last block is incomplete, terminate it with a single 'one' bit
- * followed by zeros. */
- ctx->block[ctx->block_used] = 0x80;
- memset(ctx->block + ctx->block_used + 1, 0,
- AES_BLOCK_SIZE - (ctx->block_used + 1));
-
- mask = ctx->k2;
- }
-
- unsigned i;
- for (i = 0; i < AES_BLOCK_SIZE; i++) {
- out[i] = ctx->block[i] ^ mask[i];
- }
-
- return EVP_Cipher(&ctx->cipher_ctx, out, out, AES_BLOCK_SIZE);
- }
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