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<?php
/**
* Utility functions for generating hashes
*
* This is based in part on Drupal code as well as what we used in our own code
* prior to introduction of this class, by way of MWCryptRand.
*
* This program is free software; you can redistribute it 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 more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
*/
class MWCryptHash {
/**
* The hash algorithm being used
*/
protected static $algo = null;
/**
* The number of bytes outputted by the hash algorithm
*/
protected static $hashLength = [
true => null,
false => null,
];
/**
* Decide on the best acceptable hash algorithm we have available for hash()
* @return string A hash algorithm
*/
public static function hashAlgo() {
if ( !is_null( self::$algo ) ) {
return self::$algo;
}
$algos = hash_algos();
$preference = [ 'whirlpool', 'sha256', 'sha1', 'md5' ];
foreach ( $preference as $algorithm ) {
if ( in_array( $algorithm, $algos ) ) {
self::$algo = $algorithm;
return self::$algo;
}
}
// We only reach here if no acceptable hash is found in the list, this should
// be a technical impossibility since most of php's hash list is fixed and
// some of the ones we list are available as their own native functions
// But since we already require at least 5.2 and hash() was default in
// 5.1.2 we don't bother falling back to methods like sha1 and md5.
throw new DomainException( "Could not find an acceptable hashing function in hash_algos()" );
}
/**
* Return the byte-length output of the hash algorithm we are
* using in self::hash and self::hmac.
*
* @param bool $raw True to return the length for binary data, false to
* return for hex-encoded
* @return int Number of bytes the hash outputs
*/
public static function hashLength( $raw = true ) {
$raw = (bool)$raw;
if ( is_null( self::$hashLength[$raw] ) ) {
self::$hashLength[$raw] = strlen( self::hash( '', $raw ) );
}
return self::$hashLength[$raw];
}
/**
* Generate an acceptably unstable one-way-hash of some text
* making use of the best hash algorithm that we have available.
*
* @param string $data
* @param bool $raw True to return binary data, false to return it hex-encoded
* @return string A hash of the data
*/
public static function hash( $data, $raw = true ) {
return hash( self::hashAlgo(), $data, $raw );
}
/**
* Generate an acceptably unstable one-way-hmac of some text
* making use of the best hash algorithm that we have available.
*
* @param string $data
* @param string $key
* @param bool $raw True to return binary data, false to return it hex-encoded
* @return string An hmac hash of the data + key
*/
public static function hmac( $data, $key, $raw = true ) {
if ( !is_string( $key ) ) {
// a fatal error in HHVM; an exception will at least give us a stack trace
throw new InvalidArgumentException( 'Invalid key type: ' . gettype( $key ) );
}
return hash_hmac( self::hashAlgo(), $data, $key, $raw );
}
}
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