library/Zend/Crypt/DiffieHellman.php

   1 <?php
   2 /**
   3  * Zend Framework
   4  *
   5  * LICENSE
   6  *
   7  * This source file is subject to the new BSD license that is bundled
   8  * with this package in the file LICENSE.txt.
   9  * It is also available through the world-wide-web at this URL:
  10  * http://framework.zend.com/license/new-bsd
  11  * If you did not receive a copy of the license and are unable to
  12  * obtain it through the world-wide-web, please send an email
  13  * to license@zend.com so we can send you a copy immediately.
  14  *
  15  * @category   Zend
  16  * @package    Zend_Crypt
  17  * @subpackage DiffieHellman
  18  * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)
  19  * @license    http://framework.zend.com/license/new-bsd     New BSD License
  20  * @version    $Id$
  21  */
  22
  23 /**
  24  * PHP implementation of the Diffie-Hellman public key encryption algorithm.
  25  * Allows two unassociated parties to establish a joint shared secret key
  26  * to be used in encrypting subsequent communications.
  27  *
  28  * @category   Zend
  29  * @package    Zend_Crypt
  30  * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)
  31  * @license    http://framework.zend.com/license/new-bsd     New BSD License
  32  */
  33 class Zend_Crypt_DiffieHellman
  34 {
  35
  36     /**
  37      * Static flag to select whether to use PHP5.3's openssl extension
  38      * if available.
  39      *
  40      * @var boolean
  41      */
  42     public static $useOpenssl = true;
  43
  44     /**
  45      * Default large prime number; required by the algorithm.
  46      *
  47      * @var string
  48      */
  49     private $_prime = null;
  50
  51     /**
  52      * The default generator number. This number must be greater than 0 but
  53      * less than the prime number set.
  54      *
  55      * @var string
  56      */
  57     private $_generator = null;
  58
  59     /**
  60      * A private number set by the local user. It's optional and will
  61      * be generated if not set.
  62      *
  63      * @var string
  64      */
  65     private $_privateKey = null;
  66
  67     /**
  68      * BigInteger support object courtesy of Zend_Crypt_Math
  69      *
  70      * @var Zend_Crypt_Math_BigInteger
  71      */
  72     private $_math = null;
  73
  74     /**
  75      * The public key generated by this instance after calling generateKeys().
  76      *
  77      * @var string
  78      */
  79     private $_publicKey = null;
  80
  81     /**
  82      * The shared secret key resulting from a completed Diffie Hellman
  83      * exchange
  84      *
  85      * @var string
  86      */
  87     private $_secretKey = null;
  88
  89     /**
  90      * Constants
  91      */
  92     const BINARY = 'binary';
  93     const NUMBER = 'number';
  94     const BTWOC  = 'btwoc';
  95
  96     /**
  97      * Constructor; if set construct the object using the parameter array to
  98      * set values for Prime, Generator and Private.
  99      * If a Private Key is not set, one will be generated at random.
 100      *
 101      * @param string $prime
 102      * @param string $generator
 103      * @param string $privateKey
 104      * @param string $privateKeyType
 105      * @return void
 106      */
 107     public function __construct($prime, $generator, $privateKey = null, $privateKeyType = self::NUMBER)
 108     {
 109         $this->setPrime($prime);
 110         $this->setGenerator($generator);
 111         if (!is_null($privateKey)) {
 112             $this->setPrivateKey($privateKey, $privateKeyType);
 113         }
 114         $this->setBigIntegerMath();
 115     }
 116
 117     /**
 118      * Generate own public key. If a private number has not already been
 119      * set, one will be generated at this stage.
 120      *
 121      * @return Zend_Crypt_DiffieHellman
 122      */
 123     public function generateKeys()
 124     {
 125         if (function_exists('openssl_dh_compute_key') && self::$useOpenssl !== false) {
 126             $details = array();
 127             $details['p'] = $this->getPrime();
 128             $details['g'] = $this->getGenerator();
 129             if ($this->hasPrivateKey()) {
 130                 $details['priv_key'] = $this->getPrivateKey();
 131             }
 132             $opensslKeyResource = openssl_pkey_new( array('dh' => $details) );
 133             $data = openssl_pkey_get_details($opensslKeyResource);
 134             $this->setPrivateKey($data['dh']['priv_key'], self::BINARY);
 135             $this->setPublicKey($data['dh']['pub_key'], self::BINARY);
 136         } else {
 137             // Private key is lazy generated in the absence of PHP 5.3's ext/openssl
 138             $publicKey = $this->_math->powmod($this->getGenerator(), $this->getPrivateKey(), $this->getPrime());
 139             $this->setPublicKey($publicKey);
 140         }
 141         return $this;
 142     }
 143
 144     /**
 145      * Setter for the value of the public number
 146      *
 147      * @param string $number
 148      * @param string $type
 149      * @return Zend_Crypt_DiffieHellman
 150      */
 151     public function setPublicKey($number, $type = self::NUMBER)
 152     {
 153         if ($type == self::BINARY) {
 154             $number = $this->_math->fromBinary($number);
 155         }
 156         if (!preg_match("/^\d+$/", $number)) {
 157             require_once('Zend/Crypt/DiffieHellman/Exception.php');
 158             throw new Zend_Crypt_DiffieHellman_Exception('invalid parameter; not a positive natural number');
 159         }
 160         $this->_publicKey = (string) $number;
 161         return $this;
 162     }
 163
 164     /**
 165      * Returns own public key for communication to the second party to this
 166      * transaction.
 167      *
 168      * @param string $type
 169      * @return string
 170      */
 171     public function getPublicKey($type = self::NUMBER)
 172     {
 173         if (is_null($this->_publicKey)) {
 174             require_once 'Zend/Crypt/DiffieHellman/Exception.php';
 175             throw new Zend_Crypt_DiffieHellman_Exception('A public key has not yet been generated using a prior call to generateKeys()');
 176         }
 177         if ($type == self::BINARY) {
 178             return $this->_math->toBinary($this->_publicKey);
 179         } elseif ($type == self::BTWOC) {
 180             return $this->_math->btwoc($this->_math->toBinary($this->_publicKey));
 181         }
 182         return $this->_publicKey;
 183     }
 184
 185     /**
 186      * Compute the shared secret key based on the public key received from the
 187      * the second party to this transaction. This should agree to the secret
 188      * key the second party computes on our own public key.
 189      * Once in agreement, the key is known to only to both parties.
 190      * By default, the function expects the public key to be in binary form
 191      * which is the typical format when being transmitted.
 192      *
 193      * If you need the binary form of the shared secret key, call
 194      * getSharedSecretKey() with the optional parameter for Binary output.
 195      *
 196      * @param string $publicKey
 197      * @param string $type
 198      * @return mixed
 199      */
 200     public function computeSecretKey($publicKey, $type = self::NUMBER, $output = self::NUMBER)
 201     {
 202         if ($type == self::BINARY) {
 203             $publicKey = $this->_math->fromBinary($publicKey);
 204         }
 205         if (!preg_match("/^\d+$/", $publicKey)) {
 206             require_once('Zend/Crypt/DiffieHellman/Exception.php');
 207             throw new Zend_Crypt_DiffieHellman_Exception('invalid parameter; not a positive natural number');
 208         }
 209         if (function_exists('openssl_dh_compute_key') && self::$useOpenssl !== false) {
 210             $this->_secretKey = openssl_dh_compute_key($publicKey, $this->getPublicKey());
 211         } else {
 212             $this->_secretKey = $this->_math->powmod($publicKey, $this->getPrivateKey(), $this->getPrime());
 213         }
 214         return $this->getSharedSecretKey($output);
 215     }
 216
 217     /**
 218      * Return the computed shared secret key from the DiffieHellman transaction
 219      *
 220      * @param string $type
 221      * @return string
 222      */
 223     public function getSharedSecretKey($type = self::NUMBER)
 224     {
 225         if (!isset($this->_secretKey)) {
 226             require_once('Zend/Crypt/DiffieHellman/Exception.php');
 227             throw new Zend_Crypt_DiffieHellman_Exception('A secret key has not yet been computed; call computeSecretKey()');
 228         }
 229         if ($type == self::BINARY) {
 230             return $this->_math->toBinary($this->_secretKey);
 231         } elseif ($type == self::BTWOC) {
 232             return $this->_math->btwoc($this->_math->toBinary($this->_secretKey));
 233         }
 234         return $this->_secretKey;
 235     }
 236
 237     /**
 238      * Setter for the value of the prime number
 239      *
 240      * @param string $number
 241      * @return Zend_Crypt_DiffieHellman
 242      */
 243     public function setPrime($number)
 244     {
 245         if (!preg_match("/^\d+$/", $number) || $number < 11) {
 246             require_once('Zend/Crypt/DiffieHellman/Exception.php');
 247             throw new Zend_Crypt_DiffieHellman_Exception('invalid parameter; not a positive natural number or too small: should be a large natural number prime');
 248         }
 249         $this->_prime = (string) $number;
 250         return $this;
 251     }
 252
 253     /**
 254      * Getter for the value of the prime number
 255      *
 256      * @return string
 257      */
 258     public function getPrime()
 259     {
 260         if (!isset($this->_prime)) {
 261             require_once('Zend/Crypt/DiffieHellman/Exception.php');
 262             throw new Zend_Crypt_DiffieHellman_Exception('No prime number has been set');
 263         }
 264         return $this->_prime;
 265     }
 266
 267
 268     /**
 269      * Setter for the value of the generator number
 270      *
 271      * @param string $number
 272      * @return Zend_Crypt_DiffieHellman
 273      */
 274     public function setGenerator($number)
 275     {
 276         if (!preg_match("/^\d+$/", $number) || $number < 2) {
 277             require_once('Zend/Crypt/DiffieHellman/Exception.php');
 278             throw new Zend_Crypt_DiffieHellman_Exception('invalid parameter; not a positive natural number greater than 1');
 279         }
 280         $this->_generator = (string) $number;
 281         return $this;
 282     }
 283
 284     /**
 285      * Getter for the value of the generator number
 286      *
 287      * @return string
 288      */
 289     public function getGenerator()
 290     {
 291         if (!isset($this->_generator)) {
 292             require_once('Zend/Crypt/DiffieHellman/Exception.php');
 293             throw new Zend_Crypt_DiffieHellman_Exception('No generator number has been set');
 294         }
 295         return $this->_generator;
 296     }
 297
 298     /**
 299      * Setter for the value of the private number
 300      *
 301      * @param string $number
 302      * @param string $type
 303      * @return Zend_Crypt_DiffieHellman
 304      */
 305     public function setPrivateKey($number, $type = self::NUMBER)
 306     {
 307         if ($type == self::BINARY) {
 308             $number = $this->_math->fromBinary($number);
 309         }
 310         if (!preg_match("/^\d+$/", $number)) {
 311             require_once('Zend/Crypt/DiffieHellman/Exception.php');
 312             throw new Zend_Crypt_DiffieHellman_Exception('invalid parameter; not a positive natural number');
 313         }
 314         $this->_privateKey = (string) $number;
 315         return $this;
 316     }
 317
 318     /**
 319      * Getter for the value of the private number
 320      *
 321      * @param string $type
 322      * @return string
 323      */
 324     public function getPrivateKey($type = self::NUMBER)
 325     {
 326         if (!$this->hasPrivateKey()) {
 327             $this->setPrivateKey($this->_generatePrivateKey(), self::BINARY);
 328         }
 329         if ($type == self::BINARY) {
 330             return $this->_math->toBinary($this->_privateKey);
 331         } elseif ($type == self::BTWOC) {
 332             return $this->_math->btwoc($this->_math->toBinary($this->_privateKey));
 333         }
 334         return $this->_privateKey;
 335     }
 336
 337     /**
 338      * Check whether a private key currently exists.
 339      *
 340      * @return boolean
 341      */
 342     public function hasPrivateKey()
 343     {
 344         return isset($this->_privateKey);
 345     }
 346
 347     /**
 348      * Setter to pass an extension parameter which is used to create
 349      * a specific BigInteger instance for a specific extension type.
 350      * Allows manual setting of the class in case of an extension
 351      * problem or bug.
 352      *
 353      * @param string $extension
 354      * @return void
 355      */
 356     public function setBigIntegerMath($extension = null)
 357     {
 358         /**
 359          * @see Zend_Crypt_Math
 360          */
 361         require_once 'Zend/Crypt/Math.php';
 362         $this->_math = new Zend_Crypt_Math($extension);
 363     }
 364
 365     /**
 366      * In the event a private number/key has not been set by the user,
 367      * or generated by ext/openssl, a best attempt will be made to
 368      * generate a random key. Having a random number generator installed
 369      * on linux/bsd is highly recommended! The alternative is not recommended
 370      * for production unless without any other option.
 371      *
 372      * @return string
 373      */
 374     protected function _generatePrivateKey()
 375     {
 376         $rand = $this->_math->rand($this->getGenerator(), $this->getPrime());
 377         return $rand;
 378     }
 379
 380 }