includes/libs/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 ?string $algo = null;
  31
  32         /**
  33          * The number of bytes outputted by the hash algorithm
  34          */
  35         protected static int $hashLength;
  36
  37         /**
  38          * Decide on the best acceptable hash algorithm we have available for hash()
  39          * @return string A hash algorithm
  40          */
  41         public static function hashAlgo() {
  42                 $algorithm = self::$algo;
  43                 if ( $algorithm !== null ) {
  44                         return $algorithm;
  45                 }
  46
  47                 $algos = hash_hmac_algos();
  48                 $preference = [ 'whirlpool', 'sha256' ];
  49
  50                 foreach ( $preference as $algorithm ) {
  51                         if ( in_array( $algorithm, $algos, true ) ) {
  52                                 self::$algo = $algorithm;
  53                                 return $algorithm;
  54                         }
  55                 }
  56
  57                 throw new DomainException( 'Could not find an acceptable hashing function.' );
  58         }
  59
  60         /**
  61          * Return the byte-length output of the hash algorithm we are
  62          * using in self::hash and self::hmac.
  63          *
  64          * @param bool $raw True to return the length for binary data, false to
  65          *   return for hex-encoded
  66          * @return int Number of bytes the hash outputs
  67          */
  68         public static function hashLength( $raw = true ) {
  69                 self::$hashLength ??= strlen( self::hash( '', true ) );
  70                 // Optimisation: Skip computing the length of non-raw hashes.
  71                 // The algos in hashAlgo() all produce a digest that is a multiple
  72                 // of 8 bits, where hex is always twice the length of binary byte length.
  73                 return $raw ? self::$hashLength : self::$hashLength * 2;
  74         }
  75
  76         /**
  77          * Generate a cryptographic hash value (message digest) for a string,
  78          * making use of the best hash algorithm that we have available.
  79          *
  80          * @param string $data
  81          * @param bool $raw True to return binary data, false to return it hex-encoded
  82          * @return string A hash of the data
  83          */
  84         public static function hash( $data, $raw = true ) {
  85                 return hash( self::hashAlgo(), $data, $raw );
  86         }
  87
  88         /**
  89          * Generate a keyed cryptographic hash value (HMAC) for a string,
  90          * making use of the best hash algorithm that we have available.
  91          *
  92          * @param string $data
  93          * @param string $key
  94          * @param bool $raw True to return binary data, false to return it hex-encoded
  95          * @return string An HMAC hash of the data + key
  96          */
  97         public static function hmac( $data, $key, $raw = true ) {
  98                 if ( !is_string( $key ) ) {
  99                         // hash_hmac tolerates non-string (would return null with warning)
 100                         throw new InvalidArgumentException( 'Invalid key type: ' . get_debug_type( $key ) );
 101                 }
 102                 return hash_hmac( self::hashAlgo(), $data, $key, $raw );
 103         }
 104
 105 }