GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libcrypto/cmac/cmac.c Lines: 82 117 70.1 %
Date: 2017-11-13 Branches: 40 74 54.1 %

Line Branch Exec Source
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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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}