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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,
 * 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,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 */

#include "modes.h"
#include <string.h>

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

#define STRICT_ALIGNMENT 1
#if defined(__i386) || defined(__i386__) || \
    defined(__x86_64) || defined(__x86_64__) || \
    defined(_M_IX86) || defined(_M_AMD64) || defined(_M_X64) || \
    defined(__s390__) || defined(__s390x__)
#  undef 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 align; 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 {
                  while (len>=16) {
                        (*block)(in, out, key);
                        for(n=0; n<16; n+=sizeof(size_t))
                              *(size_t *)(out+n) ^= *(size_t *)(iv+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 {
                  size_t c;
                  while (len>=16) {
                        (*block)(in, tmp.c, key);
                        for(n=0; n<16; n+=sizeof(size_t)) {
                              c = *(size_t *)(in+n);
                              *(size_t *)(out+n) =
                              *(size_t *)(tmp.c+n) ^ *(size_t *)(ivec+n);
                              *(size_t *)(ivec+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;
      }
}

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