| 1 | <?php |
| 2 | /* |
| 3 | +--------------------------------------------------------------------+ |
| 4 | | Copyright CiviCRM LLC. All rights reserved. | |
| 5 | | | |
| 6 | | This work is published under the GNU AGPLv3 license with some | |
| 7 | | permitted exceptions and without any warranty. For full license | |
| 8 | | and copyright information, see https://civicrm.org/licensing | |
| 9 | +--------------------------------------------------------------------+ |
| 10 | */ |
| 11 | |
| 12 | /** |
| 13 | * |
| 14 | * @package CRM |
| 15 | * @copyright CiviCRM LLC https://civicrm.org/licensing |
| 16 | */ |
| 17 | |
| 18 | /** |
| 19 | * A utility which signs and verifies a list of key-value pairs |
| 20 | * |
| 21 | * FIXME: Add TTL support? |
| 22 | * |
| 23 | * ``` |
| 24 | * $signer = new CRM_Utils_Signer('myprivatekey', array('param1','param2')); |
| 25 | * $params = array( |
| 26 | * 'param1' => 'hello', |
| 27 | * 'param2' => 'world', |
| 28 | * ); |
| 29 | * $token = $signer->sign($params); |
| 30 | * ... |
| 31 | * assertTrue($signer->validate($token, $params)); |
| 32 | * ``` |
| 33 | */ |
| 34 | class CRM_Utils_Signer { |
| 35 | /** |
| 36 | * Expected length of the salt |
| 37 | * |
| 38 | * @var int |
| 39 | */ |
| 40 | const SALT_LEN = 4; |
| 41 | |
| 42 | /** |
| 43 | * Instantiate a signature-processor |
| 44 | * |
| 45 | * @param string $secret |
| 46 | * private. |
| 47 | * @param array $paramNames |
| 48 | * Array, fields which should be part of the signature. |
| 49 | */ |
| 50 | public function __construct($secret, $paramNames) { |
| 51 | // ensure consistent serialization of payloads |
| 52 | sort($paramNames); |
| 53 | $this->secret = $secret; |
| 54 | $this->paramNames = $paramNames; |
| 55 | // chosen to be valid in URLs but not in salt or md5 |
| 56 | $this->signDelim = "_"; |
| 57 | $this->defaultSalt = CRM_Utils_String::createRandom(self::SALT_LEN, CRM_Utils_String::ALPHANUMERIC); |
| 58 | } |
| 59 | |
| 60 | /** |
| 61 | * Generate a signature for a set of key-value pairs |
| 62 | * |
| 63 | * @param array $params |
| 64 | * Array, key-value pairs. |
| 65 | * @param string $salt |
| 66 | * the salt (if known) or NULL (for auto-generated). |
| 67 | * @return string, the full public token representing the signature |
| 68 | */ |
| 69 | public function sign($params, $salt = NULL) { |
| 70 | $message = []; |
| 71 | $message['secret'] = $this->secret; |
| 72 | $message['payload'] = []; |
| 73 | if (empty($salt)) { |
| 74 | $message['salt'] = $this->createSalt(); |
| 75 | } |
| 76 | else { |
| 77 | $message['salt'] = $salt; |
| 78 | } |
| 79 | // recall: paramNames is pre-sorted for stability |
| 80 | foreach ($this->paramNames as $paramName) { |
| 81 | if (isset($params[$paramName])) { |
| 82 | if (is_numeric($params[$paramName])) { |
| 83 | $params[$paramName] = (string) $params[$paramName]; |
| 84 | } |
| 85 | } |
| 86 | else { |
| 87 | // $paramName is not included or ===NULL |
| 88 | $params[$paramName] = ''; |
| 89 | } |
| 90 | $message['payload'][$paramName] = $params[$paramName]; |
| 91 | } |
| 92 | $token = $message['salt'] . $this->signDelim . md5(serialize($message)); |
| 93 | return $token; |
| 94 | } |
| 95 | |
| 96 | /** |
| 97 | * Determine whether a token represents a proper signature for $params |
| 98 | * |
| 99 | * @param string $token |
| 100 | * the full public token representing the signature. |
| 101 | * @param array $params |
| 102 | * Array, key-value pairs. |
| 103 | * |
| 104 | * @throws Exception |
| 105 | * @return bool, TRUE iff all $paramNames for the submitted validate($params) and the original sign($params) |
| 106 | */ |
| 107 | public function validate($token, $params) { |
| 108 | list ($salt, $signature) = explode($this->signDelim, $token); |
| 109 | if (strlen($salt) != self::SALT_LEN) { |
| 110 | throw new Exception("Token contains invalid salt [" . urlencode($token) . "]"); |
| 111 | } |
| 112 | $newToken = $this->sign($params, $salt); |
| 113 | return ($token == $newToken); |
| 114 | } |
| 115 | |
| 116 | /** |
| 117 | * @return string |
| 118 | */ |
| 119 | public function createSalt() { |
| 120 | // It would be more secure to generate a new value but liable to run this |
| 121 | // many times on certain admin pages; so instead we'll re-use the hash. |
| 122 | return $this->defaultSalt; |
| 123 | } |
| 124 | |
| 125 | } |