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aes_cbc.c

/* crypto/aes/aes_cbc.c -*- mode:C; c-file-style: "eay" -*- */
/* ====================================================================
 * Copyright (c) 1998-2002 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.
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 * 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.
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 * 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/)"
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 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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 */

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

#include <openssl/aes.h>
#include "aes_locl.h"

#if !defined(OPENSSL_FIPS_AES_ASM)
void AES_cbc_encrypt(const unsigned char *in, unsigned char *out,
                 const unsigned long length, const AES_KEY *key,
                 unsigned char *ivec, const int enc) {

      unsigned long n;
      unsigned long len = length;
      unsigned char tmp[AES_BLOCK_SIZE];
      const unsigned char *iv = ivec;

      assert(in && out && key && ivec);
      assert((AES_ENCRYPT == enc)||(AES_DECRYPT == enc));

      if (AES_ENCRYPT == enc) {
            while (len >= AES_BLOCK_SIZE) {
                  for(n=0; n < AES_BLOCK_SIZE; ++n)
                        out[n] = in[n] ^ iv[n];
                  AES_encrypt(out, out, key);
                  iv = out;
                  len -= AES_BLOCK_SIZE;
                  in += AES_BLOCK_SIZE;
                  out += AES_BLOCK_SIZE;
            }
            if (len) {
                  for(n=0; n < len; ++n)
                        out[n] = in[n] ^ iv[n];
                  for(n=len; n < AES_BLOCK_SIZE; ++n)
                        out[n] = iv[n];
                  AES_encrypt(out, out, key);
                  iv = out;
            }
            memcpy(ivec,iv,AES_BLOCK_SIZE);
      } else if (in != out) {
            while (len >= AES_BLOCK_SIZE) {
                  AES_decrypt(in, out, key);
                  for(n=0; n < AES_BLOCK_SIZE; ++n)
                        out[n] ^= iv[n];
                  iv = in;
                  len -= AES_BLOCK_SIZE;
                  in  += AES_BLOCK_SIZE;
                  out += AES_BLOCK_SIZE;
            }
            if (len) {
                  AES_decrypt(in,tmp,key);
                  for(n=0; n < len; ++n)
                        out[n] = tmp[n] ^ iv[n];
                  iv = in;
            }
            memcpy(ivec,iv,AES_BLOCK_SIZE);
      } else {
            while (len >= AES_BLOCK_SIZE) {
                  memcpy(tmp, in, AES_BLOCK_SIZE);
                  AES_decrypt(in, out, key);
                  for(n=0; n < AES_BLOCK_SIZE; ++n)
                        out[n] ^= ivec[n];
                  memcpy(ivec, tmp, AES_BLOCK_SIZE);
                  len -= AES_BLOCK_SIZE;
                  in += AES_BLOCK_SIZE;
                  out += AES_BLOCK_SIZE;
            }
            if (len) {
                  memcpy(tmp, in, AES_BLOCK_SIZE);
                  AES_decrypt(tmp, out, key);
                  for(n=0; n < len; ++n)
                        out[n] ^= ivec[n];
                  for(n=len; n < AES_BLOCK_SIZE; ++n)
                        out[n] = tmp[n];
                  memcpy(ivec, tmp, AES_BLOCK_SIZE);
            }
      }
}
#endif

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