/* ====================================================================

 * 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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 * ==================================================================== */

#include <assert.h>

#include <string.h>

#include "internal.h"

#include "../../internal.h"

void CRYPTO_cbc128_encrypt(const uint8_t *in, uint8_t *out, size_t len,

                           const AES_KEY *key, uint8_t ivec[16],

                           block128_f block) {

  assert(key != NULL && ivec != NULL);

  if (len == 0) {

    // Avoid |ivec| == |iv| in the |memcpy| below, which is not legal in C.

    return;

  }

  assert(in != NULL && out != NULL);

  size_t n;

  const uint8_t *iv = ivec;

  while (len >= 16) {

    CRYPTO_xor16(out, in, iv);

    (*block)(out, out, key);

    iv = out;

    len -= 16;

    in += 16;

    out += 16;

  }

  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;

  }

  OPENSSL_memcpy(ivec, iv, 16);

}

void CRYPTO_cbc128_decrypt(const uint8_t *in, uint8_t *out, size_t len,

                           const AES_KEY *key, uint8_t ivec[16],

                           block128_f block) {

  assert(key != NULL && ivec != NULL);

  if (len == 0) {

    // Avoid |ivec| == |iv| in the |memcpy| below, which is not legal in C.

    return;

  }

  assert(in != NULL && out != NULL);

  const uintptr_t inptr = (uintptr_t) in;

  const uintptr_t outptr = (uintptr_t) out;

  // If |in| and |out| alias, |in| must be ahead.

  assert(inptr >= outptr || inptr + len <= outptr);

  size_t n;

  alignas(16) uint8_t tmp[16];

  if ((inptr >= 32 && outptr <= inptr - 32) || inptr < outptr) {

    // If |out| is at least two blocks behind |in| or completely disjoint, there

    // is no need to decrypt to a temporary block.

    const uint8_t *iv = ivec;

    while (len >= 16) {

      (*block)(in, out, key);

      CRYPTO_xor16(out, out, iv);

      iv = in;

      len -= 16;

      in += 16;

      out += 16;

    }

    OPENSSL_memcpy(ivec, iv, 16);

  } else {

    static_assert(16 % sizeof(crypto_word_t) == 0,

                  "block cannot be evenly divided into words");

    while (len >= 16) {

      (*block)(in, tmp, key);

      for (n = 0; n < 16; n += sizeof(crypto_word_t)) {

        crypto_word_t c = CRYPTO_load_word_le(in + n);

        CRYPTO_store_word_le(out + n, CRYPTO_load_word_le(tmp + n) ^

                                          CRYPTO_load_word_le(ivec + n));

        CRYPTO_store_word_le(ivec + n, c);

      }

      len -= 16;

      in += 16;

      out += 16;

    }

  }

  while (len) {

    uint8_t c;

    (*block)(in, tmp, key);

    for (n = 0; n < 16 && n < len; ++n) {

      c = in[n];

      out[n] = tmp[n] ^ ivec[n];

      ivec[n] = c;

    }

    if (len <= 16) {

      for (; n < 16; ++n) {

        ivec[n] = in[n];

      }

      break;

    }

    len -= 16;

    in += 16;

    out += 16;

  }

}