9db1a0017a
cryptography.io depends on this. Specifically, it assumes that any time a CBC-mode cipher is defined, CMAC is also defined. This is incorrect; CMAC also requires an irreducible polynomial to represent GF(2^b). However, one is indeed defined for 64-bit block ciphers such as 3DES. Import tests from CAVP to test it. I've omitted the 65536-byte inputs because they're huge and FileTest doesn't like lines that long. Change-Id: I35b1e4975f61c757c70616f9b372b91746fc7e4a Reviewed-on: https://boringssl-review.googlesource.com/28466 Commit-Queue: David Benjamin <davidben@google.com> Reviewed-by: Adam Langley <agl@google.com>
279 lines
8.5 KiB
C
279 lines
8.5 KiB
C
/* ====================================================================
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* Copyright (c) 2010 The OpenSSL Project. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. All advertising materials mentioning features or use of this
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* software must display the following acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
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*
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* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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* endorse or promote products derived from this software without
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* prior written permission. For written permission, please contact
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* licensing@OpenSSL.org.
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*
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* 5. Products derived from this software may not be called "OpenSSL"
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* nor may "OpenSSL" appear in their names without prior written
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* permission of the OpenSSL Project.
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*
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* 6. Redistributions of any form whatsoever must retain the following
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* acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
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*
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* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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* ==================================================================== */
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#include <openssl/cmac.h>
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#include <assert.h>
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#include <string.h>
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#include <openssl/aes.h>
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#include <openssl/cipher.h>
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#include <openssl/mem.h>
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#include "../internal.h"
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struct cmac_ctx_st {
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EVP_CIPHER_CTX cipher_ctx;
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// k1 and k2 are the CMAC subkeys. See
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// https://tools.ietf.org/html/rfc4493#section-2.3
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uint8_t k1[AES_BLOCK_SIZE];
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uint8_t k2[AES_BLOCK_SIZE];
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// Last (possibly partial) scratch
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uint8_t block[AES_BLOCK_SIZE];
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// block_used contains the number of valid bytes in |block|.
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unsigned block_used;
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};
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static void CMAC_CTX_init(CMAC_CTX *ctx) {
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EVP_CIPHER_CTX_init(&ctx->cipher_ctx);
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}
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static void CMAC_CTX_cleanup(CMAC_CTX *ctx) {
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EVP_CIPHER_CTX_cleanup(&ctx->cipher_ctx);
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OPENSSL_cleanse(ctx->k1, sizeof(ctx->k1));
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OPENSSL_cleanse(ctx->k2, sizeof(ctx->k2));
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OPENSSL_cleanse(ctx->block, sizeof(ctx->block));
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}
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int AES_CMAC(uint8_t out[16], const uint8_t *key, size_t key_len,
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const uint8_t *in, size_t in_len) {
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const EVP_CIPHER *cipher;
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switch (key_len) {
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case 16:
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cipher = EVP_aes_128_cbc();
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break;
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case 32:
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cipher = EVP_aes_256_cbc();
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break;
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default:
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return 0;
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}
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size_t scratch_out_len;
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CMAC_CTX ctx;
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CMAC_CTX_init(&ctx);
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const int ok = CMAC_Init(&ctx, key, key_len, cipher, NULL /* engine */) &&
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CMAC_Update(&ctx, in, in_len) &&
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CMAC_Final(&ctx, out, &scratch_out_len);
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CMAC_CTX_cleanup(&ctx);
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return ok;
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}
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CMAC_CTX *CMAC_CTX_new(void) {
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CMAC_CTX *ctx = OPENSSL_malloc(sizeof(*ctx));
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if (ctx != NULL) {
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CMAC_CTX_init(ctx);
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}
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return ctx;
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}
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void CMAC_CTX_free(CMAC_CTX *ctx) {
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if (ctx == NULL) {
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return;
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}
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CMAC_CTX_cleanup(ctx);
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OPENSSL_free(ctx);
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}
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int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in) {
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if (!EVP_CIPHER_CTX_copy(&out->cipher_ctx, &in->cipher_ctx)) {
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return 0;
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}
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OPENSSL_memcpy(out->k1, in->k1, AES_BLOCK_SIZE);
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OPENSSL_memcpy(out->k2, in->k2, AES_BLOCK_SIZE);
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OPENSSL_memcpy(out->block, in->block, AES_BLOCK_SIZE);
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out->block_used = in->block_used;
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return 1;
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}
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// binary_field_mul_x_128 treats the 128 bits at |in| as an element of GF(2¹²⁸)
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// with a hard-coded reduction polynomial and sets |out| as x times the input.
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//
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// See https://tools.ietf.org/html/rfc4493#section-2.3
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static void binary_field_mul_x_128(uint8_t out[16], const uint8_t in[16]) {
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unsigned i;
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// Shift |in| to left, including carry.
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for (i = 0; i < 15; i++) {
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out[i] = (in[i] << 1) | (in[i+1] >> 7);
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}
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// If MSB set fixup with R.
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const uint8_t carry = in[0] >> 7;
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out[i] = (in[i] << 1) ^ ((0 - carry) & 0x87);
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}
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// binary_field_mul_x_64 behaves like |binary_field_mul_x_128| but acts on an
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// element of GF(2⁶⁴).
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//
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// See https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-38b.pdf
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static void binary_field_mul_x_64(uint8_t out[8], const uint8_t in[8]) {
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unsigned i;
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// Shift |in| to left, including carry.
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for (i = 0; i < 7; i++) {
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out[i] = (in[i] << 1) | (in[i+1] >> 7);
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}
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// If MSB set fixup with R.
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const uint8_t carry = in[0] >> 7;
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out[i] = (in[i] << 1) ^ ((0 - carry) & 0x1b);
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}
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static const uint8_t kZeroIV[AES_BLOCK_SIZE] = {0};
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int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t key_len,
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const EVP_CIPHER *cipher, ENGINE *engine) {
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uint8_t scratch[AES_BLOCK_SIZE];
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size_t block_size = EVP_CIPHER_block_size(cipher);
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if ((block_size != AES_BLOCK_SIZE && block_size != 8 /* 3-DES */) ||
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EVP_CIPHER_key_length(cipher) != key_len ||
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!EVP_EncryptInit_ex(&ctx->cipher_ctx, cipher, NULL, key, kZeroIV) ||
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!EVP_Cipher(&ctx->cipher_ctx, scratch, kZeroIV, block_size) ||
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// Reset context again ready for first data.
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!EVP_EncryptInit_ex(&ctx->cipher_ctx, NULL, NULL, NULL, kZeroIV)) {
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return 0;
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}
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if (block_size == AES_BLOCK_SIZE) {
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binary_field_mul_x_128(ctx->k1, scratch);
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binary_field_mul_x_128(ctx->k2, ctx->k1);
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} else {
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binary_field_mul_x_64(ctx->k1, scratch);
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binary_field_mul_x_64(ctx->k2, ctx->k1);
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}
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ctx->block_used = 0;
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return 1;
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}
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int CMAC_Reset(CMAC_CTX *ctx) {
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ctx->block_used = 0;
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return EVP_EncryptInit_ex(&ctx->cipher_ctx, NULL, NULL, NULL, kZeroIV);
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}
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int CMAC_Update(CMAC_CTX *ctx, const uint8_t *in, size_t in_len) {
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size_t block_size = EVP_CIPHER_CTX_block_size(&ctx->cipher_ctx);
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assert(block_size <= AES_BLOCK_SIZE);
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uint8_t scratch[AES_BLOCK_SIZE];
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if (ctx->block_used > 0) {
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size_t todo = block_size - ctx->block_used;
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if (in_len < todo) {
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todo = in_len;
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}
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OPENSSL_memcpy(ctx->block + ctx->block_used, in, todo);
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in += todo;
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in_len -= todo;
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ctx->block_used += todo;
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// If |in_len| is zero then either |ctx->block_used| is less than
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// |block_size|, in which case we can stop here, or |ctx->block_used| is
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// exactly |block_size| but there's no more data to process. In the latter
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// case we don't want to process this block now because it might be the last
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// block and that block is treated specially.
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if (in_len == 0) {
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return 1;
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}
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assert(ctx->block_used == block_size);
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if (!EVP_Cipher(&ctx->cipher_ctx, scratch, ctx->block, block_size)) {
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return 0;
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}
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}
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// Encrypt all but one of the remaining blocks.
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while (in_len > block_size) {
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if (!EVP_Cipher(&ctx->cipher_ctx, scratch, in, block_size)) {
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return 0;
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}
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in += block_size;
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in_len -= block_size;
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}
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OPENSSL_memcpy(ctx->block, in, in_len);
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ctx->block_used = in_len;
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return 1;
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}
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int CMAC_Final(CMAC_CTX *ctx, uint8_t *out, size_t *out_len) {
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size_t block_size = EVP_CIPHER_CTX_block_size(&ctx->cipher_ctx);
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assert(block_size <= AES_BLOCK_SIZE);
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*out_len = block_size;
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if (out == NULL) {
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return 1;
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}
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const uint8_t *mask = ctx->k1;
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if (ctx->block_used != block_size) {
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// If the last block is incomplete, terminate it with a single 'one' bit
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// followed by zeros.
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ctx->block[ctx->block_used] = 0x80;
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OPENSSL_memset(ctx->block + ctx->block_used + 1, 0,
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block_size - (ctx->block_used + 1));
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mask = ctx->k2;
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}
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for (unsigned i = 0; i < block_size; i++) {
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out[i] = ctx->block[i] ^ mask[i];
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}
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return EVP_Cipher(&ctx->cipher_ctx, out, out, block_size);
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}
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