includes/utils/MWCryptRand.php

   1 <?php
   2 /**
   3  * A cryptographic random generator class used for generating secret keys
   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.
   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  * @author Daniel Friesen
  24  * @file
  25  */
  26
  27 use MediaWiki\MediaWikiServices;
  28
  29 class MWCryptRand {
  30         /**
  31          * @deprecated since 1.32
  32          * @return CryptRand
  33          */
  34         protected static function singleton() {
  35                 return MediaWikiServices::getInstance()->getCryptRand();
  36         }
  37
  38         /**
  39          * Return a boolean indicating whether or not the source used for cryptographic
  40          * random bytes generation in the previously run generate* call
  41          * was cryptographically strong.
  42          *
  43          * @deprecated since 1.32, always returns true
  44          *
  45          * @return bool Always true
  46          */
  47         public static function wasStrong() {
  48                 return true;
  49         }
  50
  51         /**
  52          * Generate a run of cryptographically random data and return
  53          * it in raw binary form.
  54          *
  55          * @deprecated since 1.32, use random_bytes()
  56          *
  57          * @param int $bytes The number of bytes of random data to generate
  58          * @return string Raw binary random data
  59          */
  60         public static function generate( $bytes ) {
  61                 return random_bytes( floor( $bytes ) );
  62         }
  63
  64         /**
  65          * Generate a run of cryptographically random data and return
  66          * it in hexadecimal string format.
  67          *
  68          * @param int $chars The number of hex chars of random data to generate
  69          * @return string Hexadecimal random data
  70          */
  71         public static function generateHex( $chars ) {
  72                 // hex strings are 2x the length of raw binary so we divide the length in half
  73                 // odd numbers will result in a .5 that leads the generate() being 1 character
  74                 // short, so we use ceil() to ensure that we always have enough bytes
  75                 $bytes = ceil( $chars / 2 );
  76                 // Generate the data and then convert it to a hex string
  77                 $hex = bin2hex( random_bytes( $bytes ) );
  78
  79                 // A bit of paranoia here, the caller asked for a specific length of string
  80                 // here, and it's possible (eg when given an odd number) that we may actually
  81                 // have at least 1 char more than they asked for. Just in case they made this
  82                 // call intending to insert it into a database that does truncation we don't
  83                 // want to give them too much and end up with their database and their live
  84                 // code having two different values because part of what we gave them is truncated
  85                 // hence, we strip out any run of characters longer than what we were asked for.
  86                 return substr( $hex, 0, $chars );
  87         }
  88 }