curl_des.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) Steve Holme, <[email protected]>.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * SPDX-License-Identifier: curl
 *
 ***************************************************************************/

#include "curl_setup.h"

#if defined(USE_CURL_NTLM_CORE) && \
  (defined(USE_GNUTLS) ||          \
   defined(USE_OS400CRYPTO) ||     \
   defined(USE_WIN32_CRYPTO))

#include "curl_des.h"

/*
 * Curl_des_set_odd_parity()
 *
 * This is used to apply odd parity to the given byte array. It is typically
 * used by when a cryptography engine does not have its own version.
 *
 * The function is a port of the Java based oddParity() function over at:
 *
 * https://davenport.sourceforge.net/ntlm.html
 *
 * Parameters:
 *
 * bytes       [in/out] - The data whose parity bits are to be adjusted for
 *                        odd parity.
 * len         [out]    - The length of the data.
 */
void Curl_des_set_odd_parity(unsigned char *bytes, size_t len)
{
  size_t i;

  for(i = 0; i < len; i++) {
    unsigned char b = bytes[i];

    bool needs_parity = (((b >> 7) ^ (b >> 6) ^ (b >> 5) ^
                          (b >> 4) ^ (b >> 3) ^ (b >> 2) ^
                          (b >> 1)) & 0x01) == 0;

    if(needs_parity)
      bytes[i] |= 0x01;
    else
      bytes[i] &= 0xfe;
  }
}

#endif