includes/utils/MWCryptHash.php

   1 <?php
   2 /**
   3  * Utility functions for generating hashes
   4  *
   5  * This is based in part on Drupal code as well as what we used in our own code
   6  * prior to introduction of this class, by way of MWCryptRand.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  */
  25
  26 class MWCryptHash {
  27         /**
  28          * The hash algorithm being used
  29          */
  30         protected static $algo = null;
  31
  32         /**
  33          * The number of bytes outputted by the hash algorithm
  34          */
  35         protected static $hashLength = array(
  36                 true => null,
  37                 false => null,
  38         );
  39
  40         /**
  41          * Decide on the best acceptable hash algorithm we have available for hash()
  42          * @return string A hash algorithm
  43          */
  44         public static function hashAlgo() {
  45                 if ( !is_null( self::$algo ) ) {
  46                         return self::$algo;
  47                 }
  48
  49                 $algos = hash_algos();
  50                 $preference = array( 'whirlpool', 'sha256', 'sha1', 'md5' );
  51
  52                 foreach ( $preference as $algorithm ) {
  53                         if ( in_array( $algorithm, $algos ) ) {
  54                                 self::$algo = $algorithm;
  55                                 wfDebug( __METHOD__ . ': Using the ' . self::$algo . " hash algorithm.\n" );
  56
  57                                 return self::$algo;
  58                         }
  59                 }
  60
  61                 // We only reach here if no acceptable hash is found in the list, this should
  62                 // be a technical impossibility since most of php's hash list is fixed and
  63                 // some of the ones we list are available as their own native functions
  64                 // But since we already require at least 5.2 and hash() was default in
  65                 // 5.1.2 we don't bother falling back to methods like sha1 and md5.
  66                 throw new DomainException( "Could not find an acceptable hashing function in hash_algos()" );
  67         }
  68
  69         /**
  70          * Return the byte-length output of the hash algorithm we are
  71          * using in self::hash and self::hmac.
  72          *
  73          * @param boolean $raw True to return the length for binary data, false to
  74          *   return for hex-encoded
  75          * @return int Number of bytes the hash outputs
  76          */
  77         public static function hashLength( $raw = true ) {
  78                 $raw = (bool)$raw;
  79                 if ( is_null( self::$hashLength[$raw] ) ) {
  80                         self::$hashLength[$raw] = strlen( self::hash( '', $raw ) );
  81                 }
  82
  83                 return self::$hashLength[$raw];
  84         }
  85
  86         /**
  87          * Generate an acceptably unstable one-way-hash of some text
  88          * making use of the best hash algorithm that we have available.
  89          *
  90          * @param string $data
  91          * @param boolean $raw True to return binary data, false to return it hex-encoded
  92          * @return string A hash of the data
  93          */
  94         public static function hash( $data, $raw = true ) {
  95                 return hash( self::hashAlgo(), $data, $raw );
  96         }
  97
  98         /**
  99          * Generate an acceptably unstable one-way-hmac of some text
 100          * making use of the best hash algorithm that we have available.
 101          *
 102          * @param string $data
 103          * @param string $key
 104          * @param boolean $raw True to return binary data, false to return it hex-encoded
 105          * @return string An hmac hash of the data + key
 106          */
 107         public static function hmac( $data, $key, $raw = true ) {
 108                 return hash_hmac( self::hashAlgo(), $data, $key, $raw );
 109         }
 110
 111 }