crypto/modes/cbc128.c

/* ====================================================================
 * Copyright (c) 2008 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
 *    openssl-core@openssl.org.
 *
 * 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,
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 */

#include <openssl/crypto.h>
#include "modes_lcl.h"
#include <string.h>

#ifndef MODES_DEBUG
# ifndef NDEBUG
#  define NDEBUG
# endif
#endif
#include <assert.h>

#ifndef STRICT_ALIGNMENT
# define STRICT_ALIGNMENT 0
#endif

void CRYPTO_cbc128_encrypt(const unsigned char *in, unsigned char *out,
                           size_t len, const void *key,
                           unsigned char ivec[16], block128_f block)
{
    size_t n;
    const unsigned char *iv = ivec;

    assert(in && out && key && ivec);

#if !defined(OPENSSL_SMALL_FOOTPRINT)
    if (STRICT_ALIGNMENT &&
        ((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 0) {
        while (len >= 16) {
            for (n = 0; n < 16; ++n)
                out[n] = in[n] ^ iv[n];
            (*block) (out, out, key);
            iv = out;
            len -= 16;
            in += 16;
            out += 16;
        }
    } else {
        while (len >= 16) {
            for (n = 0; n < 16; n += sizeof(size_t))
                *(size_t *)(out + n) =
                    *(size_t *)(in + n) ^ *(size_t *)(iv + n);
            (*block) (out, out, key);
            iv = out;
            len -= 16;
            in += 16;
            out += 16;
        }
    }
#endif
    while (len) {
        for (n = 0; n < 16 && n < len; ++n)
            out[n] = in[n] ^ iv[n];
        for (; n < 16; ++n)
            out[n] = iv[n];
        (*block) (out, out, key);
        iv = out;
        if (len <= 16)
            break;
        len -= 16;
        in += 16;
        out += 16;
    }
    memcpy(ivec, iv, 16);
}

void CRYPTO_cbc128_decrypt(const unsigned char *in, unsigned char *out,
                           size_t len, const void *key,
                           unsigned char ivec[16], block128_f block)
{
    size_t n;
    union {
        size_t t[16 / sizeof(size_t)];
        unsigned char c[16];
    } tmp;

    assert(in && out && key && ivec);

#if !defined(OPENSSL_SMALL_FOOTPRINT)
    if (in != out) {
        const unsigned char *iv = ivec;

        if (STRICT_ALIGNMENT &&
            ((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 0) {
            while (len >= 16) {
                (*block) (in, out, key);
                for (n = 0; n < 16; ++n)
                    out[n] ^= iv[n];
                iv = in;
                len -= 16;
                in += 16;
                out += 16;
            }
        } else if (16 % sizeof(size_t) == 0) { /* always true */
            while (len >= 16) {
                size_t *out_t = (size_t *)out, *iv_t = (size_t *)iv;

                (*block) (in, out, key);
                for (n = 0; n < 16 / sizeof(size_t); n++)
                    out_t[n] ^= iv_t[n];
                iv = in;
                len -= 16;
                in += 16;
                out += 16;
            }
        }
        memcpy(ivec, iv, 16);
    } else {
        if (STRICT_ALIGNMENT &&
            ((size_t)in | (size_t)out | (size_t)ivec) % sizeof(size_t) != 0) {
            unsigned char c;
            while (len >= 16) {
                (*block) (in, tmp.c, key);
                for (n = 0; n < 16; ++n) {
                    c = in[n];
                    out[n] = tmp.c[n] ^ ivec[n];
                    ivec[n] = c;
                }
                len -= 16;
                in += 16;
                out += 16;
            }
        } else if (16 % sizeof(size_t) == 0) { /* always true */
            while (len >= 16) {
                size_t c, *out_t = (size_t *)out, *ivec_t = (size_t *)ivec;
                const size_t *in_t = (const size_t *)in;

                (*block) (in, tmp.c, key);
                for (n = 0; n < 16 / sizeof(size_t); n++) {
                    c = in_t[n];
                    out_t[n] = tmp.t[n] ^ ivec_t[n];
                    ivec_t[n] = c;
                }
                len -= 16;
                in += 16;
                out += 16;
            }
        }
    }
#endif
    while (len) {
        unsigned char c;
        (*block) (in, tmp.c, key);
        for (n = 0; n < 16 && n < len; ++n) {
            c = in[n];
            out[n] = tmp.c[n] ^ ivec[n];
            ivec[n] = c;
        }
        if (len <= 16) {
            for (; n < 16; ++n)
                ivec[n] = in[n];
            break;
        }
        len -= 16;
        in += 16;
        out += 16;
    }
}