275 lines
8.0 KiB
C
275 lines
8.0 KiB
C
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/*
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* Copyright 2010-2023 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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/*
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* CMAC low level APIs are deprecated for public use, but still ok for internal
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* use.
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*/
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#include "internal/deprecated.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "internal/cryptlib.h"
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#include <openssl/cmac.h>
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#include <openssl/err.h>
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#define LOCAL_BUF_SIZE 2048
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struct CMAC_CTX_st {
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/* Cipher context to use */
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EVP_CIPHER_CTX *cctx;
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/* Keys k1 and k2 */
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unsigned char k1[EVP_MAX_BLOCK_LENGTH];
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unsigned char k2[EVP_MAX_BLOCK_LENGTH];
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/* Temporary block */
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unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
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/* Last (possibly partial) block */
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unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
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/* Number of bytes in last block: -1 means context not initialised */
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int nlast_block;
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};
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/* Make temporary keys K1 and K2 */
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static void make_kn(unsigned char *k1, const unsigned char *l, int bl)
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{
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int i;
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unsigned char c = l[0], carry = c >> 7, cnext;
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/* Shift block to left, including carry */
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for (i = 0; i < bl - 1; i++, c = cnext)
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k1[i] = (c << 1) | ((cnext = l[i + 1]) >> 7);
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/* If MSB set fixup with R */
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k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b));
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}
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CMAC_CTX *CMAC_CTX_new(void)
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{
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CMAC_CTX *ctx;
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if ((ctx = OPENSSL_malloc(sizeof(*ctx))) == NULL)
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return NULL;
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ctx->cctx = EVP_CIPHER_CTX_new();
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if (ctx->cctx == NULL) {
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OPENSSL_free(ctx);
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return NULL;
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}
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ctx->nlast_block = -1;
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return ctx;
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}
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void CMAC_CTX_cleanup(CMAC_CTX *ctx)
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{
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EVP_CIPHER_CTX_reset(ctx->cctx);
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OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
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OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
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OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
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OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
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ctx->nlast_block = -1;
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}
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EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
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{
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return ctx->cctx;
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}
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void CMAC_CTX_free(CMAC_CTX *ctx)
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{
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if (!ctx)
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return;
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CMAC_CTX_cleanup(ctx);
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EVP_CIPHER_CTX_free(ctx->cctx);
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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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{
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int bl;
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if (in->nlast_block == -1)
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return 0;
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if ((bl = EVP_CIPHER_CTX_get_block_size(in->cctx)) < 0)
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return 0;
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if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx))
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return 0;
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memcpy(out->k1, in->k1, bl);
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memcpy(out->k2, in->k2, bl);
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memcpy(out->tbl, in->tbl, bl);
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memcpy(out->last_block, in->last_block, bl);
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out->nlast_block = in->nlast_block;
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return 1;
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}
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int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
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const EVP_CIPHER *cipher, ENGINE *impl)
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{
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static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 };
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/* All zeros means restart */
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if (!key && !cipher && !impl && keylen == 0) {
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/* Not initialised */
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if (ctx->nlast_block == -1)
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return 0;
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if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
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return 0;
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memset(ctx->tbl, 0, EVP_CIPHER_CTX_get_block_size(ctx->cctx));
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ctx->nlast_block = 0;
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return 1;
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}
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/* Initialise context */
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if (cipher != NULL) {
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/* Ensure we can't use this ctx until we also have a key */
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ctx->nlast_block = -1;
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if (!EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL))
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return 0;
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}
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/* Non-NULL key means initialisation complete */
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if (key != NULL) {
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int bl;
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/* If anything fails then ensure we can't use this ctx */
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ctx->nlast_block = -1;
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if (EVP_CIPHER_CTX_get0_cipher(ctx->cctx) == NULL)
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return 0;
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if (EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen) <= 0)
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return 0;
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if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv))
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return 0;
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if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
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return 0;
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if (EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl) <= 0)
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return 0;
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make_kn(ctx->k1, ctx->tbl, bl);
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make_kn(ctx->k2, ctx->k1, bl);
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OPENSSL_cleanse(ctx->tbl, bl);
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/* Reset context again ready for first data block */
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if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
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return 0;
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/* Zero tbl so resume works */
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memset(ctx->tbl, 0, bl);
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ctx->nlast_block = 0;
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}
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return 1;
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}
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int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
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{
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const unsigned char *data = in;
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int bl;
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size_t max_burst_blocks, cipher_blocks;
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unsigned char buf[LOCAL_BUF_SIZE];
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if (ctx->nlast_block == -1)
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return 0;
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if (dlen == 0)
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return 1;
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if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
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return 0;
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/* Copy into partial block if we need to */
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if (ctx->nlast_block > 0) {
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size_t nleft;
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nleft = bl - ctx->nlast_block;
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if (dlen < nleft)
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nleft = dlen;
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memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
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dlen -= nleft;
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ctx->nlast_block += nleft;
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/* If no more to process return */
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if (dlen == 0)
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return 1;
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data += nleft;
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/* Else not final block so encrypt it */
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if (EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl) <= 0)
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return 0;
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}
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/* Encrypt all but one of the complete blocks left */
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max_burst_blocks = LOCAL_BUF_SIZE / bl;
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cipher_blocks = (dlen - 1) / bl;
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if (max_burst_blocks == 0) {
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/*
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* When block length is greater than local buffer size,
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* use ctx->tbl as cipher output.
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*/
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while (dlen > (size_t)bl) {
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if (EVP_Cipher(ctx->cctx, ctx->tbl, data, bl) <= 0)
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return 0;
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dlen -= bl;
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data += bl;
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}
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} else {
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while (cipher_blocks > max_burst_blocks) {
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if (EVP_Cipher(ctx->cctx, buf, data, max_burst_blocks * bl) <= 0)
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return 0;
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dlen -= max_burst_blocks * bl;
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data += max_burst_blocks * bl;
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cipher_blocks -= max_burst_blocks;
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}
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if (cipher_blocks > 0) {
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if (EVP_Cipher(ctx->cctx, buf, data, cipher_blocks * bl) <= 0)
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return 0;
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dlen -= cipher_blocks * bl;
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data += cipher_blocks * bl;
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memcpy(ctx->tbl, &buf[(cipher_blocks - 1) * bl], bl);
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}
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}
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/* Copy any data left to last block buffer */
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memcpy(ctx->last_block, data, dlen);
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ctx->nlast_block = dlen;
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return 1;
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}
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int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
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{
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int i, bl, lb;
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if (ctx->nlast_block == -1)
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return 0;
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if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
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return 0;
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if (poutlen != NULL)
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*poutlen = (size_t)bl;
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if (!out)
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return 1;
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lb = ctx->nlast_block;
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/* Is last block complete? */
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if (lb == bl) {
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for (i = 0; i < bl; i++)
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out[i] = ctx->last_block[i] ^ ctx->k1[i];
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} else {
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ctx->last_block[lb] = 0x80;
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if (bl - lb > 1)
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memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
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for (i = 0; i < bl; i++)
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out[i] = ctx->last_block[i] ^ ctx->k2[i];
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}
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if (EVP_Cipher(ctx->cctx, out, out, bl) <= 0) {
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OPENSSL_cleanse(out, bl);
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return 0;
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}
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return 1;
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}
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int CMAC_resume(CMAC_CTX *ctx)
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{
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if (ctx->nlast_block == -1)
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return 0;
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/*
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* The buffer "tbl" contains the last fully encrypted block which is the
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* last IV (or all zeroes if no last encrypted block). The last block has
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* not been modified since CMAC_final(). So reinitialising using the last
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* decrypted block will allow CMAC to continue after calling
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* CMAC_Final().
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*/
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return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl);
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}
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