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<?php
/**
* Zend Framework
*
* LICENSE
*
* This source file is subject to the new BSD license that is bundled
* with this package in the file LICENSE.txt.
* It is also available through the world-wide-web at this URL:
* http://framework.zend.com/license/new-bsd
* If you did not receive a copy of the license and are unable to
* obtain it through the world-wide-web, please send an email
* to license@zend.com so we can send you a copy immediately.
*
* @category Zend
* @package Zend_Crypt
* @subpackage DiffieHellman
* @copyright Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
* @license http://framework.zend.com/license/new-bsd New BSD License
* @version $Id: DiffieHellman.php 16971 2009-07-22 18:05:45Z mikaelkael $
*/
/**
* PHP implementation of the Diffie-Hellman public key encryption algorithm.
* Allows two unassociated parties to establish a joint shared secret key
* to be used in encrypting subsequent communications.
*
* @category Zend
* @package Zend_Crypt
* @copyright Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
* @license http://framework.zend.com/license/new-bsd New BSD License
*/
class Zend_Crypt_DiffieHellman
{
/**
* Static flag to select whether to use PHP5.3's openssl extension
* if available.
*
* @var boolean
*/
public static $useOpenssl = true;
/**
* Default large prime number; required by the algorithm.
*
* @var string
*/
private $_prime = null;
/**
* The default generator number. This number must be greater than 0 but
* less than the prime number set.
*
* @var string
*/
private $_generator = null;
/**
* A private number set by the local user. It's optional and will
* be generated if not set.
*
* @var string
*/
private $_privateKey = null;
/**
* BigInteger support object courtesy of Zend_Crypt_Math
*
* @var Zend_Crypt_Math_BigInteger
*/
private $_math = null;
/**
* The public key generated by this instance after calling generateKeys().
*
* @var string
*/
private $_publicKey = null;
/**
* The shared secret key resulting from a completed Diffie Hellman
* exchange
*
* @var string
*/
private $_secretKey = null;
/**
* Constants
*/
const BINARY = 'binary';
const NUMBER = 'number';
const BTWOC = 'btwoc';
/**
* Constructor; if set construct the object using the parameter array to
* set values for Prime, Generator and Private.
* If a Private Key is not set, one will be generated at random.
*
* @param string $prime
* @param string $generator
* @param string $privateKey
* @param string $privateKeyType
* @return void
*/
public function __construct($prime, $generator, $privateKey = null, $privateKeyType = self::NUMBER)
{
$this->setPrime($prime);
$this->setGenerator($generator);
if (!is_null($privateKey)) {
$this->setPrivateKey($privateKey, $privateKeyType);
}
$this->setBigIntegerMath();
}
/**
* Generate own public key. If a private number has not already been
* set, one will be generated at this stage.
*
* @return Zend_Crypt_DiffieHellman
*/
public function generateKeys()
{
if (function_exists('openssl_dh_compute_key') && self::$useOpenssl !== false) {
$details = array();
$details['p'] = $this->getPrime();
$details['g'] = $this->getGenerator();
if ($this->hasPrivateKey()) {
$details['priv_key'] = $this->getPrivateKey();
}
$opensslKeyResource = openssl_pkey_new( array('dh' => $details) );
$data = openssl_pkey_get_details($opensslKeyResource);
$this->setPrivateKey($data['dh']['priv_key'], self::BINARY);
$this->setPublicKey($data['dh']['pub_key'], self::BINARY);
} else {
// Private key is lazy generated in the absence of PHP 5.3's ext/openssl
$publicKey = $this->_math->powmod($this->getGenerator(), $this->getPrivateKey(), $this->getPrime());
$this->setPublicKey($publicKey);
}
return $this;
}
/**
* Setter for the value of the public number
*
* @param string $number
* @param string $type
* @return Zend_Crypt_DiffieHellman
*/
public function setPublicKey($number, $type = self::NUMBER)
{
if ($type == self::BINARY) {
$number = $this->_math->fromBinary($number);
}
if (!preg_match("/^\d+$/", $number)) {
require_once('Zend/Crypt/DiffieHellman/Exception.php');
throw new Zend_Crypt_DiffieHellman_Exception('invalid parameter; not a positive natural number');
}
$this->_publicKey = (string) $number;
return $this;
}
/**
* Returns own public key for communication to the second party to this
* transaction.
*
* @param string $type
* @return string
*/
public function getPublicKey($type = self::NUMBER)
{
if (is_null($this->_publicKey)) {
require_once 'Zend/Crypt/DiffieHellman/Exception.php';
throw new Zend_Crypt_DiffieHellman_Exception('A public key has not yet been generated using a prior call to generateKeys()');
}
if ($type == self::BINARY) {
return $this->_math->toBinary($this->_publicKey);
} elseif ($type == self::BTWOC) {
return $this->_math->btwoc($this->_math->toBinary($this->_publicKey));
}
return $this->_publicKey;
}
/**
* Compute the shared secret key based on the public key received from the
* the second party to this transaction. This should agree to the secret
* key the second party computes on our own public key.
* Once in agreement, the key is known to only to both parties.
* By default, the function expects the public key to be in binary form
* which is the typical format when being transmitted.
*
* If you need the binary form of the shared secret key, call
* getSharedSecretKey() with the optional parameter for Binary output.
*
* @param string $publicKey
* @param string $type
* @return mixed
*/
public function computeSecretKey($publicKey, $type = self::NUMBER, $output = self::NUMBER)
{
if ($type == self::BINARY) {
$publicKey = $this->_math->fromBinary($publicKey);
}
if (!preg_match("/^\d+$/", $publicKey)) {
require_once('Zend/Crypt/DiffieHellman/Exception.php');
throw new Zend_Crypt_DiffieHellman_Exception('invalid parameter; not a positive natural number');
}
if (function_exists('openssl_dh_compute_key') && self::$useOpenssl !== false) {
$this->_secretKey = openssl_dh_compute_key($publicKey, $this->getPublicKey());
} else {
$this->_secretKey = $this->_math->powmod($publicKey, $this->getPrivateKey(), $this->getPrime());
}
return $this->getSharedSecretKey($output);
}
/**
* Return the computed shared secret key from the DiffieHellman transaction
*
* @param string $type
* @return string
*/
public function getSharedSecretKey($type = self::NUMBER)
{
if (!isset($this->_secretKey)) {
require_once('Zend/Crypt/DiffieHellman/Exception.php');
throw new Zend_Crypt_DiffieHellman_Exception('A secret key has not yet been computed; call computeSecretKey()');
}
if ($type == self::BINARY) {
return $this->_math->toBinary($this->_secretKey);
} elseif ($type == self::BTWOC) {
return $this->_math->btwoc($this->_math->toBinary($this->_secretKey));
}
return $this->_secretKey;
}
/**
* Setter for the value of the prime number
*
* @param string $number
* @return Zend_Crypt_DiffieHellman
*/
public function setPrime($number)
{
if (!preg_match("/^\d+$/", $number) || $number < 11) {
require_once('Zend/Crypt/DiffieHellman/Exception.php');
throw new Zend_Crypt_DiffieHellman_Exception('invalid parameter; not a positive natural number or too small: should be a large natural number prime');
}
$this->_prime = (string) $number;
return $this;
}
/**
* Getter for the value of the prime number
*
* @return string
*/
public function getPrime()
{
if (!isset($this->_prime)) {
require_once('Zend/Crypt/DiffieHellman/Exception.php');
throw new Zend_Crypt_DiffieHellman_Exception('No prime number has been set');
}
return $this->_prime;
}
/**
* Setter for the value of the generator number
*
* @param string $number
* @return Zend_Crypt_DiffieHellman
*/
public function setGenerator($number)
{
if (!preg_match("/^\d+$/", $number) || $number < 2) {
require_once('Zend/Crypt/DiffieHellman/Exception.php');
throw new Zend_Crypt_DiffieHellman_Exception('invalid parameter; not a positive natural number greater than 1');
}
$this->_generator = (string) $number;
return $this;
}
/**
* Getter for the value of the generator number
*
* @return string
*/
public function getGenerator()
{
if (!isset($this->_generator)) {
require_once('Zend/Crypt/DiffieHellman/Exception.php');
throw new Zend_Crypt_DiffieHellman_Exception('No generator number has been set');
}
return $this->_generator;
}
/**
* Setter for the value of the private number
*
* @param string $number
* @param string $type
* @return Zend_Crypt_DiffieHellman
*/
public function setPrivateKey($number, $type = self::NUMBER)
{
if ($type == self::BINARY) {
$number = $this->_math->fromBinary($number);
}
if (!preg_match("/^\d+$/", $number)) {
require_once('Zend/Crypt/DiffieHellman/Exception.php');
throw new Zend_Crypt_DiffieHellman_Exception('invalid parameter; not a positive natural number');
}
$this->_privateKey = (string) $number;
return $this;
}
/**
* Getter for the value of the private number
*
* @param string $type
* @return string
*/
public function getPrivateKey($type = self::NUMBER)
{
if (!$this->hasPrivateKey()) {
$this->setPrivateKey($this->_generatePrivateKey());
}
if ($type == self::BINARY) {
return $this->_math->toBinary($this->_privateKey);
} elseif ($type == self::BTWOC) {
return $this->_math->btwoc($this->_math->toBinary($this->_privateKey));
}
return $this->_privateKey;
}
/**
* Check whether a private key currently exists.
*
* @return boolean
*/
public function hasPrivateKey()
{
return isset($this->_privateKey);
}
/**
* Setter to pass an extension parameter which is used to create
* a specific BigInteger instance for a specific extension type.
* Allows manual setting of the class in case of an extension
* problem or bug.
*
* @param string $extension
* @return void
*/
public function setBigIntegerMath($extension = null)
{
/**
* @see Zend_Crypt_Math
*/
require_once 'Zend/Crypt/Math.php';
$this->_math = new Zend_Crypt_Math($extension);
}
/**
* In the event a private number/key has not been set by the user,
* or generated by ext/openssl, a best attempt will be made to
* generate a random key. Having a random number generator installed
* on linux/bsd is highly recommended! The alternative is not recommended
* for production unless without any other option.
*
* @return string
*/
protected function _generatePrivateKey()
{
$rand = $this->_math->rand($this->getGenerator(), $this->getPrime());
return $rand;
}
}
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