1<?php
2/*
3 * Copyright 2011 Google Inc.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18/**
19 * Verifies signatures using PEM encoded certificates.
20 *
21 * @author Brian Eaton <beaton@google.com>
22 */
23class Google_PemVerifier extends Google_Verifier {
24  private $publicKey;
25
26  /**
27   * Constructs a verifier from the supplied PEM-encoded certificate.
28   *
29   * $pem: a PEM encoded certificate (not a file).
30   * @param $pem
31   * @throws Google_AuthException
32   * @throws Google_Exception
33   */
34  function __construct($pem) {
35    if (!function_exists('openssl_x509_read')) {
36      throw new Google_Exception('Google API PHP client needs the openssl PHP extension');
37    }
38    $this->publicKey = openssl_x509_read($pem);
39    if (!$this->publicKey) {
40      throw new Google_AuthException("Unable to parse PEM: $pem");
41    }
42  }
43
44  function __destruct() {
45    if ($this->publicKey) {
46      openssl_x509_free($this->publicKey);
47    }
48  }
49
50  /**
51   * Verifies the signature on data.
52   *
53   * Returns true if the signature is valid, false otherwise.
54   * @param $data
55   * @param $signature
56   * @throws Google_AuthException
57   * @return bool
58   */
59  function verify($data, $signature) {
60    $status = openssl_verify($data, $signature, $this->publicKey, "sha256");
61    if ($status === -1) {
62      throw new Google_AuthException('Signature verification error: ' . openssl_error_string());
63    }
64    return $status === 1;
65  }
66}
67