cmac.c

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/* crypto/cmac/cmac.c */
/* Written by Dr Stephen N Henson ([email protected]) for the OpenSSL
 * project.
 */
/* ====================================================================
 * 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
 *    [email protected].
 *
 * 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,
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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 * ====================================================================
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "cryptlib.h"
#include <openssl/cmac.h>

#ifdef OPENSSL_FIPS
#include <openssl/fips.h>
#endif

struct CMAC_CTX_st
    {
    /* Cipher context to use */
    EVP_CIPHER_CTX cctx;
    /* Keys k1 and k2 */
    unsigned char k1[EVP_MAX_BLOCK_LENGTH];
    unsigned char k2[EVP_MAX_BLOCK_LENGTH];
    /* Temporary block */
    unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
    /* Last (possibly partial) block */
    unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
    /* Number of bytes in last block: -1 means context not initialised */
    int nlast_block;
    };


/* Make temporary keys K1 and K2 */

static void make_kn(unsigned char *k1, unsigned char *l, int bl)
    {
    int i;
    /* Shift block to left, including carry */
    for (i = 0; i < bl; i++)
        {
        k1[i] = l[i] << 1;
        if (i < bl - 1 && l[i + 1] & 0x80)
            k1[i] |= 1;
        }
    /* If MSB set fixup with R */
    if (l[0] & 0x80)
        k1[bl - 1] ^= bl == 16 ? 0x87 : 0x1b;
    }

CMAC_CTX *CMAC_CTX_new(void)
    {
    CMAC_CTX *ctx;
    ctx = OPENSSL_malloc(sizeof(CMAC_CTX));
    if (!ctx)
        return NULL;
    EVP_CIPHER_CTX_init(&ctx->cctx);
    ctx->nlast_block = -1;
    return ctx;
    }

void CMAC_CTX_cleanup(CMAC_CTX *ctx)
    {
#ifdef OPENSSL_FIPS
    if (FIPS_mode() && !ctx->cctx.engine)
        {
        FIPS_cmac_ctx_cleanup(ctx);
        return;
        }
#endif
    EVP_CIPHER_CTX_cleanup(&ctx->cctx);
    OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
    OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
    OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
    OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
    ctx->nlast_block = -1;
    }

EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
    {
    return &ctx->cctx;
    }

void CMAC_CTX_free(CMAC_CTX *ctx)
    {
    CMAC_CTX_cleanup(ctx);
    OPENSSL_free(ctx);
    }

int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
    {
    int bl;
    if (in->nlast_block == -1)
        return 0;
    if (!EVP_CIPHER_CTX_copy(&out->cctx, &in->cctx))
        return 0;
    bl = EVP_CIPHER_CTX_block_size(&in->cctx);
    memcpy(out->k1, in->k1, bl);
    memcpy(out->k2, in->k2, bl);
    memcpy(out->tbl, in->tbl, bl);
    memcpy(out->last_block, in->last_block, bl);
    out->nlast_block = in->nlast_block;
    return 1;
    }

int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen, 
            const EVP_CIPHER *cipher, ENGINE *impl)
    {
    static unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH];
#ifdef OPENSSL_FIPS
    if (FIPS_mode())
        {
        /* If we have an ENGINE need to allow non FIPS */
        if ((impl || ctx->cctx.engine)
            && !(ctx->cctx.flags & EVP_CIPH_FLAG_NON_FIPS_ALLOW))

            {
            EVPerr(EVP_F_CMAC_INIT, EVP_R_DISABLED_FOR_FIPS);
            return 0;
            }
        /* Other algorithm blocking will be done in FIPS_cmac_init,
         * via FIPS_cipherinit().
         */
        if (!impl && !ctx->cctx.engine)
            return FIPS_cmac_init(ctx, key, keylen, cipher, NULL);
        }
#endif
    /* All zeros means restart */
    if (!key && !cipher && !impl && keylen == 0)
        {
        /* Not initialised */
        if (ctx->nlast_block == -1)
            return 0;
        if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, zero_iv))
            return 0;
        memset(ctx->tbl, 0, EVP_CIPHER_CTX_block_size(&ctx->cctx));
        ctx->nlast_block = 0;
        return 1;
        }
    /* Initialiase context */
    if (cipher && !EVP_EncryptInit_ex(&ctx->cctx, cipher, impl, NULL, NULL))
        return 0;
    /* Non-NULL key means initialisation complete */
    if (key)
        {
        int bl;
        if (!EVP_CIPHER_CTX_cipher(&ctx->cctx))
            return 0;
        if (!EVP_CIPHER_CTX_set_key_length(&ctx->cctx, keylen))
            return 0;
        if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, key, zero_iv))
            return 0;
        bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
        if (!EVP_Cipher(&ctx->cctx, ctx->tbl, zero_iv, bl))
            return 0;
        make_kn(ctx->k1, ctx->tbl, bl);
        make_kn(ctx->k2, ctx->k1, bl);
        OPENSSL_cleanse(ctx->tbl, bl);
        /* Reset context again ready for first data block */
        if (!EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, zero_iv))
            return 0;
        /* Zero tbl so resume works */
        memset(ctx->tbl, 0, bl);
        ctx->nlast_block = 0;
        }
    return 1;
    }

int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
    {
    const unsigned char *data = in;
    size_t bl;
#ifdef OPENSSL_FIPS
    if (FIPS_mode() && !ctx->cctx.engine)
        return FIPS_cmac_update(ctx, in, dlen);
#endif
    if (ctx->nlast_block == -1)
        return 0;
    if (dlen == 0)
        return 1;
    bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
    /* Copy into partial block if we need to */
    if (ctx->nlast_block > 0)
        {
        size_t nleft;
        nleft = bl - ctx->nlast_block;
        if (dlen < nleft)
            nleft = dlen;
        memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
        dlen -= nleft;
        ctx->nlast_block += nleft;
        /* If no more to process return */
        if (dlen == 0)
            return 1;
        data += nleft;
        /* Else not final block so encrypt it */
        if (!EVP_Cipher(&ctx->cctx, ctx->tbl, ctx->last_block,bl))
            return 0;
        }
    /* Encrypt all but one of the complete blocks left */
    while(dlen > bl)
        {
        if (!EVP_Cipher(&ctx->cctx, ctx->tbl, data, bl))
            return 0;
        dlen -= bl;
        data += bl;
        }
    /* Copy any data left to last block buffer */
    memcpy(ctx->last_block, data, dlen);
    ctx->nlast_block = dlen;
    return 1;

    }

int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
    {
    int i, bl, lb;
#ifdef OPENSSL_FIPS
    if (FIPS_mode() && !ctx->cctx.engine)
        return FIPS_cmac_final(ctx, out, poutlen);
#endif
    if (ctx->nlast_block == -1)
        return 0;
    bl = EVP_CIPHER_CTX_block_size(&ctx->cctx);
    *poutlen = (size_t)bl;
    if (!out)
        return 1;
    lb = ctx->nlast_block;
    /* Is last block complete? */
    if (lb == bl)
        {
        for (i = 0; i < bl; i++)
            out[i] = ctx->last_block[i] ^ ctx->k1[i];
        }
    else
        {
        ctx->last_block[lb] = 0x80;
        if (bl - lb > 1)
            memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
        for (i = 0; i < bl; i++)
            out[i] = ctx->last_block[i] ^ ctx->k2[i];
        }
    if (!EVP_Cipher(&ctx->cctx, out, out, bl))
        {
        OPENSSL_cleanse(out, bl);   
        return 0;
        }
    return 1;
    }

int CMAC_resume(CMAC_CTX *ctx)
    {
    if (ctx->nlast_block == -1)
        return 0;
    /* The buffer "tbl" containes the last fully encrypted block
     * which is the last IV (or all zeroes if no last encrypted block).
     * The last block has not been modified since CMAC_final().
     * So reinitliasing using the last decrypted block will allow
     * CMAC to continue after calling CMAC_Final(). 
     */
    return EVP_EncryptInit_ex(&ctx->cctx, NULL, NULL, NULL, ctx->tbl);
    }