drupal-civicrm/sites/all/modules/civicrm/CRM/Utils/Signer.php

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2018-01-14 15:10:16 +02:00
<?php
/*
+--------------------------------------------------------------------+
| CiviCRM version 4.7 |
+--------------------------------------------------------------------+
| Copyright CiviCRM LLC (c) 2004-2017 |
+--------------------------------------------------------------------+
| This file is a part of CiviCRM. |
| |
| CiviCRM is free software; you can copy, modify, and distribute it |
| under the terms of the GNU Affero General Public License |
| Version 3, 19 November 2007 and the CiviCRM Licensing Exception. |
| |
| CiviCRM 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 Affero General Public License for more details. |
| |
| You should have received a copy of the GNU Affero General Public |
| License and the CiviCRM Licensing Exception along |
| with this program; if not, contact CiviCRM LLC |
| at info[AT]civicrm[DOT]org. If you have questions about the |
| GNU Affero General Public License or the licensing of CiviCRM, |
| see the CiviCRM license FAQ at http://civicrm.org/licensing |
+--------------------------------------------------------------------+
*/
/**
*
* @package CRM
* @copyright CiviCRM LLC (c) 2004-2017
*/
/**
* A utility which signs and verifies a list of key-value pairs
*
* FIXME: Add TTL support?
*
* @code
* $signer = new CRM_Utils_Signer('myprivatekey', array('param1','param2'));
* $params = array(
* 'param1' => 'hello',
* 'param2' => 'world',
* );
* $token = $signer->sign($params);
* ...
* assertTrue($signer->validate($token, $params));
* @endcode
*/
class CRM_Utils_Signer {
/**
* Expected length of the salt
*
* @var int
*/
const SALT_LEN = 4;
/**
* Instantiate a signature-processor
*
* @param string $secret
* private.
* @param array $paramNames
* Array, fields which should be part of the signature.
*/
public function __construct($secret, $paramNames) {
sort($paramNames); // ensure consistent serialization of payloads
$this->secret = $secret;
$this->paramNames = $paramNames;
$this->signDelim = "_"; // chosen to be valid in URLs but not in salt or md5
$this->defaultSalt = CRM_Utils_String::createRandom(self::SALT_LEN, CRM_Utils_String::ALPHANUMERIC);
}
/**
* Generate a signature for a set of key-value pairs
*
* @param array $params
* Array, key-value pairs.
* @param string $salt
* the salt (if known) or NULL (for auto-generated).
* @return string, the full public token representing the signature
*/
public function sign($params, $salt = NULL) {
$message = array();
$message['secret'] = $this->secret;
$message['payload'] = array();
if (empty($salt)) {
$message['salt'] = $this->createSalt();
}
else {
$message['salt'] = $salt;
}
// recall: paramNames is pre-sorted for stability
foreach ($this->paramNames as $paramName) {
if (isset($params[$paramName])) {
if (is_numeric($params[$paramName])) {
$params[$paramName] = (string) $params[$paramName];
}
}
else {
// $paramName is not included or ===NULL
$params[$paramName] = '';
}
$message['payload'][$paramName] = $params[$paramName];
}
$token = $message['salt'] . $this->signDelim . md5(serialize($message));
return $token;
}
/**
* Determine whether a token represents a proper signature for $params
*
* @param string $token
* the full public token representing the signature.
* @param array $params
* Array, key-value pairs.
*
* @throws Exception
* @return bool, TRUE iff all $paramNames for the submitted validate($params) and the original sign($params)
*/
public function validate($token, $params) {
list ($salt, $signature) = explode($this->signDelim, $token);
if (strlen($salt) != self::SALT_LEN) {
throw new Exception("Token contains invalid salt [" . urlencode($token) . "]");
}
$newToken = $this->sign($params, $salt);
return ($token == $newToken);
}
/**
* @return string
*/
public function createSalt() {
// It would be more secure to generate a new value but liable to run this
// many times on certain admin pages; so instead we'll re-use the hash.
return $this->defaultSalt;
}
}