+<?php
+
+use Wikimedia\Assert\Assert;
+
+/**
+ * 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
+ */
+
+/**
+ * Implements Argon2, a modern key derivation algorithm designed to resist GPU cracking and
+ * side-channel attacks.
+ *
+ * @see https://en.wikipedia.org/wiki/Argon2
+ */
+class Argon2Password extends Password {
+ /**
+ * @var null[] Array with known password_hash() option names as keys
+ */
+ private static $knownOptions = [
+ 'memory_cost' => null,
+ 'time_cost' => null,
+ 'threads' => null,
+ ];
+
+ /**
+ * @inheritDoc
+ */
+ protected function isSupported() {
+ // It is actually possible to have a PHP build with Argon2i but not Argon2id
+ return defined( 'PASSWORD_ARGON2I' ) || defined( 'PASSWORD_ARGON2ID' );
+ }
+
+ /**
+ * @return mixed[] Array of 2nd and third parmeters to password_hash()
+ */
+ private function prepareParams() {
+ switch ( $this->config['algo'] ) {
+ case 'argon2i':
+ $algo = PASSWORD_ARGON2I;
+ break;
+ case 'argon2id':
+ $algo = PASSWORD_ARGON2ID;
+ break;
+ case 'auto':
+ $algo = defined( 'PASSWORD_ARGON2ID' ) ? PASSWORD_ARGON2ID : PASSWORD_ARGON2I;
+ break;
+ default:
+ throw new LogicException( "Unexpected algo: {$this->config['algo']}" );
+
+ }
+
+ $params = array_intersect_key( $this->config, self::$knownOptions );
+
+ return [ $algo, $params ];
+ }
+
+ /**
+ * @inheritDoc
+ */
+ public function crypt( $password ) {
+ list( $algo, $params ) = $this->prepareParams();
+ $this->hash = password_hash( $password, $algo, $params );
+ }
+
+ /**
+ * @inheritDoc
+ */
+ public function equals( $other ) {
+ if ( is_string( $other ) ) {
+ return $this->verify( $other );
+ }
+
+ // Argon2 key derivation is not deterministic, can't pass objects to equals()
+ return false;
+ }
+
+ /**
+ * @inheritDoc
+ */
+ public function verify( $password ) {
+ Assert::parameterType( 'string', $password, '$password' );
+
+ return password_verify( $password, $this->hash );
+ }
+
+ /**
+ * @inheritDoc
+ */
+ public function toString() {
+ $res = ":argon2:{$this->hash}";
+ $this->assertIsSafeSize( $res );
+ return $res;
+ }
+
+ /**
+ * @inheritDoc
+ */
+ public function needsUpdate() {
+ list( $algo, $params ) = $this->prepareParams();
+ return password_needs_rehash( $this->hash, $algo, $params );
+ }
+}