<?php

/*

 * Enano - an open-source CMS capable of wiki functions, Drupal-like sidebar blocks, and everything in between

 * hmac.php - HMAC cryptographic functions

 *

 * This program is Free Software; you can redistribute and/or modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied

 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for details.

 */

function hmac_core($message, $key, $hashfunc)

{

  if ( strlen($key) % 2 == 1 )

    $key .= '0';

  if ( strlen($key) > 128 )

    $key = $hashfunc($key);

  while ( strlen($key) < 128 )

  {

    $key .= '00';

  }

  $opad = hmac_hexbytearray($key);

  $ipad = $opad;

  for ( $i = 0; $i < count($ipad); $i++ )

  {

    $opad[$i] = $opad[$i] ^ 0x5c;

    $ipad[$i] = $ipad[$i] ^ 0x36;

  }

  $opad = hmac_bytearraytostring($opad);

  $ipad = hmac_bytearraytostring($ipad);

  return $hashfunc($opad . hexdecode($hashfunc($ipad . $message)));

}

function hmac_hexbytearray($val)

{

  $val = hexdecode($val);

  return hmac_bytearray($val);

}

function hmac_bytearray($val)

{

  $val = str_split($val, 1);

  foreach ( $val as &$char )

  {

    $char = ord($char);

  }

  return $val;

}

function hmac_bytearraytostring($val)

{

  foreach ( $val as &$char )

  {

    $char = chr($char);

  }

  return implode('', $val);

}

function hmac_md5($message, $key)

{

  return hmac_core($message, $key, 'md5');

}

function hmac_sha1($message, $key)

{

  return hmac_core($message, $key, 'sha1');

}

function hmac_sha256($message, $key)

{

  require_once(ENANO_ROOT . '/includes/math.php');

  require_once(ENANO_ROOT . '/includes/diffiehellman.php');

  return hmac_core($message, $key, 'sha256');

}

?>