1<?php
2
3/**
4 * DSA Public Key
5 *
6 * @author    Jim Wigginton <terrafrost@php.net>
7 * @copyright 2015 Jim Wigginton
8 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
9 * @link      http://phpseclib.sourceforge.net
10 */
11
12namespace phpseclib3\Crypt\DSA;
13
14use phpseclib3\Crypt\Common;
15use phpseclib3\Crypt\DSA;
16use phpseclib3\Crypt\DSA\Formats\Signature\ASN1 as ASN1Signature;
17
18/**
19 * DSA Public Key
20 *
21 * @author  Jim Wigginton <terrafrost@php.net>
22 */
23final class PublicKey extends DSA implements Common\PublicKey
24{
25    use Common\Traits\Fingerprint;
26
27    /**
28     * Verify a signature
29     *
30     * @see self::verify()
31     * @param string $message
32     * @param string $signature
33     * @return mixed
34     */
35    public function verify($message, $signature)
36    {
37        $format = $this->sigFormat;
38
39        $params = $format::load($signature);
40        if ($params === false || count($params) != 2) {
41            return false;
42        }
43        extract($params);
44
45        if (self::$engines['OpenSSL'] && in_array($this->hash->getHash(), openssl_get_md_methods())) {
46            $sig = $format != 'ASN1' ? ASN1Signature::save($r, $s) : $signature;
47
48            $result = openssl_verify($message, $sig, $this->toString('PKCS8'), $this->hash->getHash());
49
50            if ($result != -1) {
51                return (bool) $result;
52            }
53        }
54
55        $q_1 = $this->q->subtract(self::$one);
56        if (!$r->between(self::$one, $q_1) || !$s->between(self::$one, $q_1)) {
57            return false;
58        }
59
60        $w = $s->modInverse($this->q);
61        $h = $this->hash->hash($message);
62        $h = $this->bits2int($h);
63        list(, $u1) = $h->multiply($w)->divide($this->q);
64        list(, $u2) = $r->multiply($w)->divide($this->q);
65        $v1 = $this->g->powMod($u1, $this->p);
66        $v2 = $this->y->powMod($u2, $this->p);
67        list(, $v) = $v1->multiply($v2)->divide($this->p);
68        list(, $v) = $v->divide($this->q);
69
70        return $v->equals($r);
71    }
72
73    /**
74     * Returns the public key
75     *
76     * @param string $type
77     * @param array $options optional
78     * @return string
79     */
80    public function toString($type, array $options = [])
81    {
82        $type = self::validatePlugin('Keys', $type, 'savePublicKey');
83
84        return $type::savePublicKey($this->p, $this->q, $this->g, $this->y, $options);
85    }
86}
87