709f828c99
* Made $hashLength an int instead of an associative array of ints. All acceptable hash functions have a digest size that is a multiple of 8 bits, so the hex length is always twice the binary (byte) length. * Added types of both $algo and $hashLength using PHP 7.4 syntax. Change-Id: Idc4592aa69a546b27bb0e77a3689f5d14d9ba7b8
105 lines
3.3 KiB
PHP
105 lines
3.3 KiB
PHP
<?php
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/**
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* Utility functions for generating hashes
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*
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* This is based in part on Drupal code as well as what we used in our own code
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* prior to introduction of this class, by way of MWCryptRand.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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*/
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class MWCryptHash {
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/**
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* The hash algorithm being used
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*/
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protected static ?string $algo = null;
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/**
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* The number of bytes outputted by the hash algorithm
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*/
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protected static int $hashLength;
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/**
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* Decide on the best acceptable hash algorithm we have available for hash()
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* @return string A hash algorithm
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*/
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public static function hashAlgo() {
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$algorithm = self::$algo;
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if ( $algorithm !== null ) {
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return $algorithm;
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}
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$algos = hash_hmac_algos();
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$preference = [ 'whirlpool', 'sha256' ];
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foreach ( $preference as $algorithm ) {
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if ( in_array( $algorithm, $algos, true ) ) {
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self::$algo = $algorithm;
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return $algorithm;
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}
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}
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throw new DomainException( 'Could not find an acceptable hashing function.' );
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}
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/**
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* Return the byte-length output of the hash algorithm we are
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* using in self::hash and self::hmac.
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*
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* @param bool $raw True to return the length for binary data, false to
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* return for hex-encoded
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* @return int Number of bytes the hash outputs
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*/
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public static function hashLength( $raw = true ) {
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self::$hashLength ??= strlen( self::hash( '', true ) );
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// Optimisation: Skip computing the length of non-raw hashes.
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// The algos in hashAlgo() all produce a digest that is a multiple
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// of 8 bits, where hex is always twice the length of binary byte length.
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return $raw ? self::$hashLength : self::$hashLength * 2;
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}
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/**
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* Generate a cryptographic hash value (message digest) for a string,
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* making use of the best hash algorithm that we have available.
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*
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* @param string $data
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* @param bool $raw True to return binary data, false to return it hex-encoded
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* @return string A hash of the data
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*/
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public static function hash( $data, $raw = true ) {
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return hash( self::hashAlgo(), $data, $raw );
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}
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/**
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* Generate a keyed cryptographic hash value (HMAC) for a string,
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* making use of the best hash algorithm that we have available.
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*
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* @param string $data
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* @param string $key
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* @param bool $raw True to return binary data, false to return it hex-encoded
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* @return string An HMAC hash of the data + key
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*/
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public static function hmac( $data, $key, $raw = true ) {
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if ( !is_string( $key ) ) {
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// hash_hmac tolerates non-string (would return null with warning)
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throw new InvalidArgumentException( 'Invalid key type: ' . gettype( $key ) );
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}
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return hash_hmac( self::hashAlgo(), $data, $key, $raw );
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}
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}
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