- /* ====================================================================
- * 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>
-
- #include "../internal.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);
- }
-
- int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in) {
- if (!EVP_CIPHER_CTX_copy(&out->cipher_ctx, &in->cipher_ctx)) {
- return 0;
- }
- OPENSSL_memcpy(out->k1, in->k1, AES_BLOCK_SIZE);
- OPENSSL_memcpy(out->k2, in->k2, AES_BLOCK_SIZE);
- OPENSSL_memcpy(out->block, in->block, AES_BLOCK_SIZE);
- out->block_used = in->block_used;
- return 1;
- }
-
- // binary_field_mul_x_128 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_128(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);
- }
-
- // binary_field_mul_x_64 behaves like |binary_field_mul_x_128| but acts on an
- // element of GF(2⁶⁴).
- //
- // See https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-38b.pdf
- static void binary_field_mul_x_64(uint8_t out[8], const uint8_t in[8]) {
- unsigned i;
-
- // Shift |in| to left, including carry.
- for (i = 0; i < 7; 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) & 0x1b);
- }
-
- 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];
-
- size_t block_size = EVP_CIPHER_block_size(cipher);
- if ((block_size != AES_BLOCK_SIZE && block_size != 8 /* 3-DES */) ||
- EVP_CIPHER_key_length(cipher) != key_len ||
- !EVP_EncryptInit_ex(&ctx->cipher_ctx, cipher, NULL, key, kZeroIV) ||
- !EVP_Cipher(&ctx->cipher_ctx, scratch, kZeroIV, block_size) ||
- // Reset context again ready for first data.
- !EVP_EncryptInit_ex(&ctx->cipher_ctx, NULL, NULL, NULL, kZeroIV)) {
- return 0;
- }
-
- if (block_size == AES_BLOCK_SIZE) {
- binary_field_mul_x_128(ctx->k1, scratch);
- binary_field_mul_x_128(ctx->k2, ctx->k1);
- } else {
- binary_field_mul_x_64(ctx->k1, scratch);
- binary_field_mul_x_64(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) {
- size_t block_size = EVP_CIPHER_CTX_block_size(&ctx->cipher_ctx);
- assert(block_size <= AES_BLOCK_SIZE);
- uint8_t scratch[AES_BLOCK_SIZE];
-
- if (ctx->block_used > 0) {
- size_t todo = block_size - ctx->block_used;
- if (in_len < todo) {
- todo = in_len;
- }
-
- OPENSSL_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
- // |block_size|, in which case we can stop here, or |ctx->block_used| is
- // exactly |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 == block_size);
-
- if (!EVP_Cipher(&ctx->cipher_ctx, scratch, ctx->block, block_size)) {
- return 0;
- }
- }
-
- // Encrypt all but one of the remaining blocks.
- while (in_len > block_size) {
- if (!EVP_Cipher(&ctx->cipher_ctx, scratch, in, block_size)) {
- return 0;
- }
- in += block_size;
- in_len -= block_size;
- }
-
- OPENSSL_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) {
- size_t block_size = EVP_CIPHER_CTX_block_size(&ctx->cipher_ctx);
- assert(block_size <= AES_BLOCK_SIZE);
-
- *out_len = block_size;
- if (out == NULL) {
- return 1;
- }
-
- const uint8_t *mask = ctx->k1;
-
- if (ctx->block_used != block_size) {
- // If the last block is incomplete, terminate it with a single 'one' bit
- // followed by zeros.
- ctx->block[ctx->block_used] = 0x80;
- OPENSSL_memset(ctx->block + ctx->block_used + 1, 0,
- block_size - (ctx->block_used + 1));
-
- mask = ctx->k2;
- }
-
- for (unsigned i = 0; i < block_size; i++) {
- out[i] = ctx->block[i] ^ mask[i];
- }
-
- return EVP_Cipher(&ctx->cipher_ctx, out, out, block_size);
- }
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