282 lines
7.8 KiB
C
282 lines
7.8 KiB
C
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/* $OpenBSD: cmac.c,v 1.10 2015/09/10 15:56:25 jsing Exp $ */
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/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
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* project.
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*/
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/* ====================================================================
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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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*/
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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 <openssl/cmac.h>
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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
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make_kn(unsigned char *k1, unsigned char *l, int bl)
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{
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int i;
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/* Shift block to left, including carry */
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for (i = 0; i < bl; i++) {
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k1[i] = l[i] << 1;
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if (i < bl - 1 && l[i + 1] & 0x80)
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k1[i] |= 1;
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}
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/* If MSB set fixup with R */
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if (l[0] & 0x80)
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k1[bl - 1] ^= bl == 16 ? 0x87 : 0x1b;
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}
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CMAC_CTX *
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CMAC_CTX_new(void)
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{
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CMAC_CTX *ctx;
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ctx = malloc(sizeof(CMAC_CTX));
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if (!ctx)
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return NULL;
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EVP_CIPHER_CTX_init(&ctx->cctx);
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ctx->nlast_block = -1;
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return ctx;
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}
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void
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CMAC_CTX_cleanup(CMAC_CTX *ctx)
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{
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EVP_CIPHER_CTX_cleanup(&ctx->cctx);
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explicit_bzero(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
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explicit_bzero(ctx->k1, EVP_MAX_BLOCK_LENGTH);
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explicit_bzero(ctx->k2, EVP_MAX_BLOCK_LENGTH);
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explicit_bzero(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 *
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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
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CMAC_CTX_free(CMAC_CTX *ctx)
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{
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if (ctx == NULL)
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return;
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CMAC_CTX_cleanup(ctx);
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free(ctx);
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}
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int
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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 (!EVP_CIPHER_CTX_copy(&out->cctx, &in->cctx))
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return 0;
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bl = EVP_CIPHER_CTX_block_size(&in->cctx);
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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
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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 unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH];
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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_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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/* Initialiase context */
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if (cipher && !EVP_EncryptInit_ex(&ctx->cctx, cipher, impl, NULL, NULL))
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return 0;
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/* Non-NULL key means initialisation complete */
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if (key) {
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int bl;
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if (!EVP_CIPHER_CTX_cipher(&ctx->cctx))
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return 0;
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if (!EVP_CIPHER_CTX_set_key_length(&ctx->cctx, keylen))
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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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bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
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if (!EVP_Cipher(&ctx->cctx, ctx->tbl, zero_iv, bl))
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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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explicit_bzero(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
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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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size_t bl;
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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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bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
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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))
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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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while (dlen > bl) {
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if (!EVP_Cipher(&ctx->cctx, ctx->tbl, data, bl))
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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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/* 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
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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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bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
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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)) {
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explicit_bzero(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
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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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/* The buffer "tbl" containes the last fully encrypted block
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* which is the last IV (or all zeroes if no last encrypted block).
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* The last block has not been modified since CMAC_final().
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* So reinitialising using the last decrypted block will allow
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* CMAC to continue after calling 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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