DiffieHellman.php

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<?php
class Zend_Crypt_DiffieHellman
{

    public static $useOpenssl = true;

    private $_prime = null;

    private $_generator = null;

    private $_privateKey = null;

    private $_math = null;

    private $_publicKey = null;

    private $_secretKey = null;

    const BINARY = 'binary';
    const NUMBER = 'number';
    const BTWOC  = 'btwoc';

    public function __construct($prime, $generator, $privateKey = null, $privateKeyType = self::NUMBER)
    {
        $this->setPrime($prime);
        $this->setGenerator($generator);
        if ($privateKey !== null) {
            $this->setPrivateKey($privateKey, $privateKeyType);
        }
        $this->setBigIntegerMath();
    }

    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;
    }

    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;
    }

    public function getPublicKey($type = self::NUMBER)
    {
        if ($this->_publicKey === null) {
            #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;
    }

    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);
    }

    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;
    }

    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;
    }

    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;
    }

    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;
    }

    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;
    }

    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;
    }

    public function getPrivateKey($type = self::NUMBER)
    {
        if (!$this->hasPrivateKey()) {
            $this->setPrivateKey($this->_generatePrivateKey(), self::BINARY);
        }
        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;
    }

    public function hasPrivateKey()
    {
        return isset($this->_privateKey);
    }

    public function setBigIntegerMath($extension = null)
    {
        #require_once 'Zend/Crypt/Math.php';
        $this->_math = new Zend_Crypt_Math($extension);
    }

    protected function _generatePrivateKey()
    {
        $rand = $this->_math->rand($this->getGenerator(), $this->getPrime());
        return $rand;
    }

}