code:
<?php
/**
 * PKCS#1 Formatted RSA Key Handler
 *
 * PHP version 5
 *
 * Used by File/X509.php
 *
 * Has the following header:
 *
 * -----BEGIN RSA PUBLIC KEY-----
 *
 * Analogous to ssh-keygen's pem format (as specified by -m)
 *
 * @category  Crypt
 * @package   RSA
 * @author    Jim Wigginton <terrafrost@php.net>
 * @copyright 2015 Jim Wigginton
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 * @link      http://phpseclib.sourceforge.net
 */

namespace phpseclib\Crypt\RSA;

use ParagonIE\ConstantTime\Base64;
use ParagonIE\ConstantTime\Hex;
use phpseclib\Crypt\AES;
use phpseclib\Crypt\DES;
use phpseclib\Crypt\Random;
use phpseclib\Crypt\TripleDES;
use phpseclib\Math\BigInteger;

/**
 * PKCS#1 Formatted RSA Key Handler
 *
 * @package RSA
 * @author  Jim Wigginton <terrafrost@php.net>
 * @access  public
 */
class PKCS1 extends PKCS
{
    /**
     * Default encryption algorithm
     *
     * @var string
     * @access private
     */
    static $defaultEncryptionAlgorithm = 'DES-EDE3-CBC';

    /**
     * Sets the default encryption algorithm
     *
     * @access public
     * @param string $algo
     */
    static function setEncryptionAlgorithm($algo)
    {
        self::$defaultEncryptionAlgorithm = $algo;
    }

    /**
     * Convert a private key to the appropriate format.
     *
     * @access public
     * @param \phpseclib\Math\BigInteger $n
     * @param \phpseclib\Math\BigInteger $e
     * @param \phpseclib\Math\BigInteger $d
     * @param array $primes
     * @param array $exponents
     * @param array $coefficients
     * @param string $password optional
     * @return string
     */
    static function savePrivateKey(BigInteger $n, BigInteger $e, BigInteger $d, $primes, $exponents, $coefficients, $password = '')
    {
        $num_primes = count($primes);
        $raw = array(
            'version' => $num_primes == 2 ? chr(0) : chr(1), // two-prime vs. multi
            'modulus' => $n->toBytes(true),
            'publicExponent' => $e->toBytes(true),
            'privateExponent' => $d->toBytes(true),
            'prime1' => $primes[1]->toBytes(true),
            'prime2' => $primes[2]->toBytes(true),
            'exponent1' => $exponents[1]->toBytes(true),
            'exponent2' => $exponents[2]->toBytes(true),
            'coefficient' => $coefficients[2]->toBytes(true)
        );

        $components = array();
        foreach ($raw as $name => $value) {
            $components[$name] = pack('Ca*a*', self::ASN1_INTEGER, self::_encodeLength(strlen($value)), $value);
        }

        $RSAPrivateKey = implode('', $components);

        if ($num_primes > 2) {
            $OtherPrimeInfos = '';
            for ($i = 3; $i <= $num_primes; $i++) {
                // OtherPrimeInfos ::= SEQUENCE SIZE(1..MAX) OF OtherPrimeInfo
                //
                // OtherPrimeInfo ::= SEQUENCE {
                //     prime             INTEGER,  -- ri
                //     exponent          INTEGER,  -- di
                //     coefficient       INTEGER   -- ti
                // }
                $OtherPrimeInfo = pack('Ca*a*', self::ASN1_INTEGER, self::_encodeLength(strlen($primes[$i]->toBytes(true))), $primes[$i]->toBytes(true));
                $OtherPrimeInfo.= pack('Ca*a*', self::ASN1_INTEGER, self::_encodeLength(strlen($exponents[$i]->toBytes(true))), $exponents[$i]->toBytes(true));
                $OtherPrimeInfo.= pack('Ca*a*', self::ASN1_INTEGER, self::_encodeLength(strlen($coefficients[$i]->toBytes(true))), $coefficients[$i]->toBytes(true));
                $OtherPrimeInfos.= pack('Ca*a*', self::ASN1_SEQUENCE, self::_encodeLength(strlen($OtherPrimeInfo)), $OtherPrimeInfo);
            }
            $RSAPrivateKey.= pack('Ca*a*', self::ASN1_SEQUENCE, self::_encodeLength(strlen($OtherPrimeInfos)), $OtherPrimeInfos);
        }

        $RSAPrivateKey = pack('Ca*a*', self::ASN1_SEQUENCE, self::_encodeLength(strlen($RSAPrivateKey)), $RSAPrivateKey);

        if (!empty($password) || is_string($password)) {
            $cipher = self::getEncryptionObject(self::$defaultEncryptionAlgorithm);
            $iv = Random::string($cipher->getBlockLength() >> 3);
            $cipher->setKey(self::generateSymmetricKey($password, $iv, $cipher->getKeyLength() >> 3));
            $cipher->setIV($iv);
            $iv = strtoupper(Hex::encode($iv));
            $RSAPrivateKey = "-----BEGIN RSA PRIVATE KEY-----\r\n" .
                     "Proc-Type: 4,ENCRYPTED\r\n" .
                     "DEK-Info: " . self::$defaultEncryptionAlgorithm . ",$iv\r\n" .
                     "\r\n" .
                     chunk_split(Base64::encode($cipher->encrypt($RSAPrivateKey)), 64) .
                     '-----END RSA PRIVATE KEY-----';
        } else {
            $RSAPrivateKey = "-----BEGIN RSA PRIVATE KEY-----\r\n" .
                     chunk_split(Base64::encode($RSAPrivateKey), 64) .
                     '-----END RSA PRIVATE KEY-----';
        }

        return $RSAPrivateKey;
    }

    /**
     * Convert a public key to the appropriate format
     *
     * @access public
     * @param \phpseclib\Math\BigInteger $n
     * @param \phpseclib\Math\BigInteger $e
     * @return string
     */
    static function savePublicKey(BigInteger $n, BigInteger $e)
    {
        $modulus = $n->toBytes(true);
        $publicExponent = $e->toBytes(true);

        // from <http://tools.ietf.org/html/rfc3447#appendix-A.1.1>:
        // RSAPublicKey ::= SEQUENCE {
        //     modulus           INTEGER,  -- n
        //     publicExponent    INTEGER   -- e
        // }
        $components = array(
            'modulus' => pack('Ca*a*', self::ASN1_INTEGER, self::_encodeLength(strlen($modulus)), $modulus),
            'publicExponent' => pack('Ca*a*', self::ASN1_INTEGER, self::_encodeLength(strlen($publicExponent)), $publicExponent)
        );

        $RSAPublicKey = pack(
            'Ca*a*a*',
            self::ASN1_SEQUENCE,
            self::_encodeLength(strlen($components['modulus']) + strlen($components['publicExponent'])),
            $components['modulus'],
            $components['publicExponent']
        );

        $RSAPublicKey = "-----BEGIN RSA PUBLIC KEY-----\r\n" .
                        chunk_split(Base64::encode($RSAPublicKey), 64) .
                        '-----END RSA PUBLIC KEY-----';

        return $RSAPublicKey;
    }
}


code:
<?php
/**
 * PKCS#8 Formatted RSA Key Handler
 *
 * PHP version 5
 *
 * Used by PHP's openssl_public_encrypt() and openssl's rsautl (when -pubin is set)
 *
 * Has the following header:
 *
 * -----BEGIN PUBLIC KEY-----
 *
 * Analogous to ssh-keygen's pkcs8 format (as specified by -m). Although PKCS8
 * is specific to private keys it's basically creating a DER-encoded wrapper
 * for keys. This just extends that same concept to public keys (much like ssh-keygen)
 *
 * @category  Crypt
 * @package   RSA
 * @author    Jim Wigginton <terrafrost@php.net>
 * @copyright 2015 Jim Wigginton
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 * @link      http://phpseclib.sourceforge.net
 */

namespace phpseclib\Crypt\RSA;

use ParagonIE\ConstantTime\Base64;
use phpseclib\Crypt\DES;
use phpseclib\Crypt\Random;
use phpseclib\Math\BigInteger;

/**
 * PKCS#8 Formatted RSA Key Handler
 *
 * @package RSA
 * @author  Jim Wigginton <terrafrost@php.net>
 * @access  public
 */
class PKCS8 extends PKCS
{
    /**
     * Convert a private key to the appropriate format.
     *
     * @access public
     * @param \phpseclib\Math\BigInteger $n
     * @param \phpseclib\Math\BigInteger $e
     * @param \phpseclib\Math\BigInteger $d
     * @param array $primes
     * @param array $exponents
     * @param array $coefficients
     * @param string $password optional
     * @return string
     */
    static function savePrivateKey(BigInteger $n, BigInteger $e, BigInteger $d, $primes, $exponents, $coefficients, $password = '')
    {
        $num_primes = count($primes);
        $raw = array(
            'version' => $num_primes == 2 ? chr(0) : chr(1), // two-prime vs. multi
            'modulus' => $n->toBytes(true),
            'publicExponent' => $e->toBytes(true),
            'privateExponent' => $d->toBytes(true),
            'prime1' => $primes[1]->toBytes(true),
            'prime2' => $primes[2]->toBytes(true),
            'exponent1' => $exponents[1]->toBytes(true),
            'exponent2' => $exponents[2]->toBytes(true),
            'coefficient' => $coefficients[2]->toBytes(true)
        );

        $components = array();
        foreach ($raw as $name => $value) {
            $components[$name] = pack('Ca*a*', self::ASN1_INTEGER, self::_encodeLength(strlen($value)), $value);
        }

        $RSAPrivateKey = implode('', $components);

        if ($num_primes > 2) {
            $OtherPrimeInfos = '';
            for ($i = 3; $i <= $num_primes; $i++) {
                // OtherPrimeInfos ::= SEQUENCE SIZE(1..MAX) OF OtherPrimeInfo
                //
                // OtherPrimeInfo ::= SEQUENCE {
                //     prime             INTEGER,  -- ri
                //     exponent          INTEGER,  -- di
                //     coefficient       INTEGER   -- ti
                // }
                $OtherPrimeInfo = pack('Ca*a*', self::ASN1_INTEGER, self::_encodeLength(strlen($primes[$i]->toBytes(true))), $primes[$i]->toBytes(true));
                $OtherPrimeInfo.= pack('Ca*a*', self::ASN1_INTEGER, self::_encodeLength(strlen($exponents[$i]->toBytes(true))), $exponents[$i]->toBytes(true));
                $OtherPrimeInfo.= pack('Ca*a*', self::ASN1_INTEGER, self::_encodeLength(strlen($coefficients[$i]->toBytes(true))), $coefficients[$i]->toBytes(true));
                $OtherPrimeInfos.= pack('Ca*a*', self::ASN1_SEQUENCE, self::_encodeLength(strlen($OtherPrimeInfo)), $OtherPrimeInfo);
            }
            $RSAPrivateKey.= pack('Ca*a*', self::ASN1_SEQUENCE, self::_encodeLength(strlen($OtherPrimeInfos)), $OtherPrimeInfos);
        }

        $RSAPrivateKey = pack('Ca*a*', self::ASN1_SEQUENCE, self::_encodeLength(strlen($RSAPrivateKey)), $RSAPrivateKey);

        $rsaOID = "\x30\x0d\x06\x09\x2a\x86\x48\x86\xf7\x0d\x01\x01\x01\x05\x00"; // hex version of MA0GCSqGSIb3DQEBAQUA
        $RSAPrivateKey = pack(
            'Ca*a*Ca*a*',
            self::ASN1_INTEGER,
            "\01\00",
            $rsaOID,
            4,
            self::_encodeLength(strlen($RSAPrivateKey)),
            $RSAPrivateKey
        );
        $RSAPrivateKey = pack('Ca*a*', self::ASN1_SEQUENCE, self::_encodeLength(strlen($RSAPrivateKey)), $RSAPrivateKey);
        if (!empty($password) || is_string($password)) {
            $salt = Random::string(8);
            $iterationCount = 2048;

            $crypto = new DES(DES::MODE_CBC);
            $crypto->setPassword($password, 'pbkdf1', 'md5', $salt, $iterationCount);
            $RSAPrivateKey = $crypto->encrypt($RSAPrivateKey);

            $parameters = pack(
                'Ca*a*Ca*N',
                self::ASN1_OCTETSTRING,
                self::_encodeLength(strlen($salt)),
                $salt,
                self::ASN1_INTEGER,
                self::_encodeLength(4),
                $iterationCount
            );
            $pbeWithMD5AndDES_CBC = "\x2a\x86\x48\x86\xf7\x0d\x01\x05\x03";

            $encryptionAlgorithm = pack(
                'Ca*a*Ca*a*',
                self::ASN1_OBJECT,
                self::_encodeLength(strlen($pbeWithMD5AndDES_CBC)),
                $pbeWithMD5AndDES_CBC,
                self::ASN1_SEQUENCE,
                self::_encodeLength(strlen($parameters)),
                $parameters
            );

            $RSAPrivateKey = pack(
                'Ca*a*Ca*a*',
                self::ASN1_SEQUENCE,
                self::_encodeLength(strlen($encryptionAlgorithm)),
                $encryptionAlgorithm,
                self::ASN1_OCTETSTRING,
                self::_encodeLength(strlen($RSAPrivateKey)),
                $RSAPrivateKey
            );

            $RSAPrivateKey = pack('Ca*a*', self::ASN1_SEQUENCE, self::_encodeLength(strlen($RSAPrivateKey)), $RSAPrivateKey);

            $RSAPrivateKey = "-----BEGIN ENCRYPTED PRIVATE KEY-----\r\n" .
                 chunk_split(Base64::encode($RSAPrivateKey), 64) .
                 '-----END ENCRYPTED PRIVATE KEY-----';
        } else {
            $RSAPrivateKey = "-----BEGIN PRIVATE KEY-----\r\n" .
                 chunk_split(Base64::encode($RSAPrivateKey), 64) .
                 '-----END PRIVATE KEY-----';
        }

        return $RSAPrivateKey;
    }

    /**
     * Convert a public key to the appropriate format
     *
     * @access public
     * @param \phpseclib\Math\BigInteger $n
     * @param \phpseclib\Math\BigInteger $e
     * @return string
     */
    static function savePublicKey(BigInteger $n, BigInteger $e)
    {
        $modulus = $n->toBytes(true);
        $publicExponent = $e->toBytes(true);

        // from <http://tools.ietf.org/html/rfc3447#appendix-A.1.1>:
        // RSAPublicKey ::= SEQUENCE {
        //     modulus           INTEGER,  -- n
        //     publicExponent    INTEGER   -- e
        // }
        $components = array(
            'modulus' => pack('Ca*a*', self::ASN1_INTEGER, self::_encodeLength(strlen($modulus)), $modulus),
            'publicExponent' => pack('Ca*a*', self::ASN1_INTEGER, self::_encodeLength(strlen($publicExponent)), $publicExponent)
        );

        $RSAPublicKey = pack(
            'Ca*a*a*',
            self::ASN1_SEQUENCE,
            self::_encodeLength(strlen($components['modulus']) + strlen($components['publicExponent'])),
            $components['modulus'],
            $components['publicExponent']
        );

        // sequence(oid(1.2.840.113549.1.1.1), null)) = rsaEncryption.
        $rsaOID = "\x30\x0d\x06\x09\x2a\x86\x48\x86\xf7\x0d\x01\x01\x01\x05\x00"; // hex version of MA0GCSqGSIb3DQEBAQUA
        $RSAPublicKey = chr(0) . $RSAPublicKey;
        $RSAPublicKey = chr(3) . self::_encodeLength(strlen($RSAPublicKey)) . $RSAPublicKey;

        $RSAPublicKey = pack(
            'Ca*a*',
            self::ASN1_SEQUENCE,
            self::_encodeLength(strlen($rsaOID . $RSAPublicKey)),
            $rsaOID . $RSAPublicKey
        );

        $RSAPublicKey = "-----BEGIN PUBLIC KEY-----\r\n" .
                        chunk_split(Base64::encode($RSAPublicKey), 64) .
                        '-----END PUBLIC KEY-----';

        return $RSAPublicKey;
    }
}

repo_name: ksuudilla/gnu

license: mit


code:
<?php
/**
 * PuTTY Formatted RSA Key Handler
 *
 * PHP version 5
 *
 * @category  Crypt
 * @package   RSA
 * @author    Jim Wigginton <terrafrost@php.net>
 * @copyright 2015 Jim Wigginton
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 * @link      http://phpseclib.sourceforge.net
 */

namespace phpseclib\Crypt\RSA;

use ParagonIE\ConstantTime\Base64;
use ParagonIE\ConstantTime\Hex;
use phpseclib\Crypt\AES;
use phpseclib\Crypt\Hash;
use phpseclib\Math\BigInteger;

/**
 * PuTTY Formatted RSA Key Handler
 *
 * @package RSA
 * @author  Jim Wigginton <terrafrost@php.net>
 * @access  public
 */
class PuTTY
{
    /**
     * Default comment
     *
     * @var string
     * @access private
     */
    static $comment = 'phpseclib-generated-key';

    /**
     * Sets the default comment
     *
     * @access public
     * @param string $comment
     */
    static function setComment($comment)
    {
        self::$comment = str_replace(array("\r", "\n"), '', $comment);
    }

    /**
     * Generate a symmetric key for PuTTY keys
     *
     * @access public
     * @param string $password
     * @param string $iv
     * @param int $length
     * @return string
     */
    static function generateSymmetricKey($password, $length)
    {
        $symkey = '';
        $sequence = 0;
        while (strlen($symkey) < $length) {
            $temp = pack('Na*', $sequence++, $password);
            $symkey.= Hex::decode(sha1($temp));
        }
        return substr($symkey, 0, $length);
    }

    /**
     * Break a public or private key down into its constituent components
     *
     * @access public
     * @param string $key
     * @param string $password optional
     * @return array
     */
    static function load($key, $password = '')
    {
        if (!is_string($key)) {
            return false;
        }

        static $one;
        if (!isset($one)) {
            $one = new BigInteger(1);
        }

        if (strpos($key, 'BEGIN SSH2 PUBLIC KEY')) {
            $data = preg_split('#[\r\n]+#', $key);
            $data = array_splice($data, 2, -1);
            $data = implode('', $data);

            $components = OpenSSH::load($data);
            if ($components === false) {
                return false;
            }

            if (!preg_match('#Comment: "(.+)"#', $key, $matches)) {
                return false;
            }
            $components['comment'] = str_replace(array('\\\\', '\"'), array('\\', '"'), $matches[1]);

            return $components;
        }

        $components = array('isPublicKey' => false);
        $key = preg_split('#\r\n|\r|\n#', $key);
        $type = trim(preg_replace('#PuTTY-User-Key-File-2: (.+)#', '$1', $key[0]));
        if ($type != 'ssh-rsa') {
            return false;
        }
        $encryption = trim(preg_replace('#Encryption: (.+)#', '$1', $key[1]));
        $components['comment'] = trim(preg_replace('#Comment: (.+)#', '$1', $key[2]));

        $publicLength = trim(preg_replace('#Public-Lines: (\d+)#', '$1', $key[3]));
        $public = Base64::decode(implode('', array_map('trim', array_slice($key, 4, $publicLength))));
        $public = substr($public, 11);
        extract(unpack('Nlength', self::_string_shift($public, 4)));
        $components['publicExponent'] = new BigInteger(self::_string_shift($public, $length), -256);
        extract(unpack('Nlength', self::_string_shift($public, 4)));
        $components['modulus'] = new BigInteger(self::_string_shift($public, $length), -256);

        $privateLength = trim(preg_replace('#Private-Lines: (\d+)#', '$1', $key[$publicLength + 4]));
        $private = Base64::decode(implode('', array_map('trim', array_slice($key, $publicLength + 5, $privateLength))));

        switch ($encryption) {
            case 'aes256-cbc':
                $symkey = static::generateSymmetricKey($password, 32);
                $crypto = new AES(AES::MODE_CBC);
        }

        if ($encryption != 'none') {
            $crypto->setKey($symkey);
            $crypto->setIV(str_repeat("\0", $crypto->getBlockLength() >> 3));
            $crypto->disablePadding();
            $private = $crypto->decrypt($private);
            if ($private === false) {
                return false;
            }
        }

        extract(unpack('Nlength', self::_string_shift($private, 4)));
        if (strlen($private) < $length) {
            return false;
        }
        $components['privateExponent'] = new BigInteger(self::_string_shift($private, $length), -256);
        extract(unpack('Nlength', self::_string_shift($private, 4)));
        if (strlen($private) < $length) {
            return false;
        }
        $components['primes'] = array(1 => new BigInteger(self::_string_shift($private, $length), -256));
        extract(unpack('Nlength', self::_string_shift($private, 4)));
        if (strlen($private) < $length) {
            return false;
        }
        $components['primes'][] = new BigInteger(self::_string_shift($private, $length), -256);

        $temp = $components['primes'][1]->subtract($one);
        $components['exponents'] = array(1 => $components['publicExponent']->modInverse($temp));
        $temp = $components['primes'][2]->subtract($one);
        $components['exponents'][] = $components['publicExponent']->modInverse($temp);

        extract(unpack('Nlength', self::_string_shift($private, 4)));
        if (strlen($private) < $length) {
            return false;
        }
        $components['coefficients'] = array(2 => new BigInteger(self::_string_shift($private, $length), -256));

        return $components;
    }

    /**
     * String Shift
     *
     * Inspired by array_shift
     *
     * @param string $string
     * @param int $index
     * @return string
     * @access private
     */
    static function _string_shift(&$string, $index = 1)
    {
        $substr = substr($string, 0, $index);
        $string = substr($string, $index);
        return $substr;
    }

    /**
     * Convert a private key to the appropriate format.
     *
     * @access public
     * @param \phpseclib\Math\BigInteger $n
     * @param \phpseclib\Math\BigInteger $e
     * @param \phpseclib\Math\BigInteger $d
     * @param array $primes
     * @param array $exponents
     * @param array $coefficients
     * @param string $password optional
     * @return string
     */
    static function savePrivateKey(BigInteger $n, BigInteger $e, BigInteger $d, $primes, $exponents, $coefficients, $password = '')
    {
        if (count($primes) != 2) {
            return false;
        }

        $raw = array(
            'modulus' => $n->toBytes(true),
            'publicExponent' => $e->toBytes(true),
            'privateExponent' => $d->toBytes(true),
            'prime1' => $primes[1]->toBytes(true),
            'prime2' => $primes[2]->toBytes(true),
            'exponent1' => $exponents[1]->toBytes(true),
            'exponent2' => $exponents[2]->toBytes(true),
            'coefficient' => $coefficients[2]->toBytes(true)
        );

        $key = "PuTTY-User-Key-File-2: ssh-rsa\r\nEncryption: ";
        $encryption = (!empty($password) || is_string($password)) ? 'aes256-cbc' : 'none';
        $key.= $encryption;
        $key.= "\r\nComment: " . self::$comment . "\r\n";
        $public = pack(
            'Na*Na*Na*',
            strlen('ssh-rsa'),
            'ssh-rsa',
            strlen($raw['publicExponent']),
            $raw['publicExponent'],
            strlen($raw['modulus']),
            $raw['modulus']
        );
        $source = pack(
            'Na*Na*Na*Na*',
            strlen('ssh-rsa'),
            'ssh-rsa',
            strlen($encryption),
            $encryption,
            strlen(self::$comment),
            self::$comment,
            strlen($public),
            $public
        );
        $public = Base64::encode($public);
        $key.= "Public-Lines: " . ((strlen($public) + 63) >> 6) . "\r\n";
        $key.= chunk_split($public, 64);
        $private = pack(
            'Na*Na*Na*Na*',
            strlen($raw['privateExponent']),
            $raw['privateExponent'],
            strlen($raw['prime1']),
            $raw['prime1'],
            strlen($raw['prime2']),
            $raw['prime2'],
            strlen($raw['coefficient']),
            $raw['coefficient']
        );
        if (empty($password) && !is_string($password)) {
            $source.= pack('Na*', strlen($private), $private);
            $hashkey = 'putty-private-key-file-mac-key';
        } else {
            $private.= Random::string(16 - (strlen($private) & 15));
            $source.= pack('Na*', strlen($private), $private);
            $crypto = new AES();

            $crypto->setKey(static::generateSymmetricKey($password, 32));
            $crypto->setIV(str_repeat("\0", $crypto->getBlockLength() >> 3));
            $crypto->disablePadding();
            $private = $crypto->encrypt($private);
            $hashkey = 'putty-private-key-file-mac-key' . $password;
        }

        $private = Base64::encode($private);
        $key.= 'Private-Lines: ' . ((strlen($private) + 63) >> 6) . "\r\n";
        $key.= chunk_split($private, 64);
        $hash = new Hash('sha1');
        $hash->setKey(sha1($hashkey, true));
        $key.= 'Private-MAC: ' . Hex::encode($hash->hash($source)) . "\r\n";

        return $key;
    }

    /**
     * Convert a public key to the appropriate format
     *
     * @access public
     * @param \phpseclib\Math\BigInteger $n
     * @param \phpseclib\Math\BigInteger $e
     * @return string
     */
    static function savePublicKey(BigInteger $n, BigInteger $e)
    {
        $n = $n->toBytes(true);
        $e = $e->toBytes(true);

        $key = pack(
            'Na*Na*Na*',
            strlen('ssh-rsa'),
            'ssh-rsa',
            strlen($e),
            $e,
            strlen($n),
            $n
        );
        $key = "---- BEGIN SSH2 PUBLIC KEY ----\r\n" .
               'Comment: "' . str_replace(array('\\', '"'), array('\\\\', '\"'), self::$comment) . "\"\r\n";
               chunk_split(Base64::encode($key), 64) .
               '---- END SSH2 PUBLIC KEY ----';

        return $key;
    }
}


code:
<?php
/**
 * Raw RSA Key Handler
 *
 * PHP version 5
 *
 * An array containing two \phpseclib\Math\BigInteger objects.
 *
 * The exponent can be indexed with any of the following:
 *
 * 0, e, exponent, publicExponent
 *
 * The modulus can be indexed with any of the following:
 *
 * 1, n, modulo, modulus
 *
 * @category  Crypt
 * @package   RSA
 * @author    Jim Wigginton <terrafrost@php.net>
 * @copyright 2015 Jim Wigginton
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 * @link      http://phpseclib.sourceforge.net
 */

namespace phpseclib\Crypt\RSA;

use phpseclib\Math\BigInteger;

/**
 * Raw RSA Key Handler
 *
 * @package RSA
 * @author  Jim Wigginton <terrafrost@php.net>
 * @access  public
 */
class Raw
{
    /**
     * Break a public or private key down into its constituent components
     *
     * @access public
     * @param string $key
     * @param string $password optional
     * @return array
     */
    static function load($key, $password = '')
    {
        if (!is_array($key)) {
            return false;
        }
        if (isset($key['isPublicKey']) && isset($key['modulus'])) {
            if (isset($key['privateExponent']) || isset($key['publicExponent'])) {
                if (!isset($key['primes'])) {
                    return $key;
                }
                if (isset($key['exponents']) && isset($key['coefficients']) && isset($key['publicExponent']) && isset($key['privateExponent'])) {
                    return $key;
                }
            }
        }
        $components = array('isPublicKey' => true);
        switch (true) {
            case isset($key['e']):
                $components['publicExponent'] = $key['e'];
                break;
            case isset($key['exponent']):
                $components['publicExponent'] = $key['exponent'];
                break;
            case isset($key['publicExponent']):
                $components['publicExponent'] = $key['publicExponent'];
                break;
            case isset($key[0]):
                $components['publicExponent'] = $key[0];
        }
        switch (true) {
            case isset($key['n']):
                $components['modulus'] = $key['n'];
                break;
            case isset($key['modulo']):
                $components['modulus'] = $key['modulo'];
                break;
            case isset($key['modulus']):
                $components['modulus'] = $key['modulus'];
                break;
            case isset($key[1]):
                $components['modulus'] = $key[1];
        }
        return isset($components['modulus']) && isset($components['publicExponent']) ? $components : false;
    }

    /**
     * Convert a public key to the appropriate format
     *
     * @access public
     * @param \phpseclib\Math\BigInteger $n
     * @param \phpseclib\Math\BigInteger $e
     * @return string
     */
    static function savePublicKey(BigInteger $n, BigInteger $e)
    {
        return array('e' => clone $e, 'n' => clone $n);
    }
}


code:
<?php
/**
 * XML Formatted RSA Key Handler
 *
 * More info:
 *
 * http://www.w3.org/TR/xmldsig-core/#sec-RSAKeyValue
 * http://en.wikipedia.org/wiki/XML_Signature
 *
 * PHP version 5
 *
 * @category  Crypt
 * @package   RSA
 * @author    Jim Wigginton <terrafrost@php.net>
 * @copyright 2015 Jim Wigginton
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 * @link      http://phpseclib.sourceforge.net
 */

namespace phpseclib\Crypt\RSA;

use ParagonIE\ConstantTime\Base64;
use phpseclib\Math\BigInteger;

/**
 * XML Formatted RSA Key Handler
 *
 * @package RSA
 * @author  Jim Wigginton <terrafrost@php.net>
 * @access  public
 */
class XML
{
    /**
     * Break a public or private key down into its constituent components
     *
     * @access public
     * @param string $key
     * @param string $password optional
     * @return array
     */
    static function load($key, $password = '')
    {
        if (!is_string($key)) {
            return false;
        }

        $components = array(
            'isPublicKey' => false,
            'primes' => array(),
            'exponents' => array(),
            'coefficients' => array()
        );

        $use_errors = libxml_use_internal_errors(true);

        $dom = new \DOMDocument();
        if (!$dom->loadXML('<xml>' . $key . '</xml>')) {
            return false;
        }
        $xpath = new \DOMXPath($dom);
        $keys = array('modulus', 'exponent', 'p', 'q', 'dp', 'dq', 'inverseq', 'd');
        foreach ($keys as $key) {
            // $dom->getElementsByTagName($key) is case-sensitive
            $temp = $xpath->query("//*[translate(local-name(), 'ABCDEFGHIJKLMNOPQRSTUVWXYZ','abcdefghijklmnopqrstuvwxyz')='$key']");
            if (!$temp->length) {
                continue;
            }
            $value = new BigInteger(Base64::decode($temp->item(0)->nodeValue), 256);
            switch ($key) {
                case 'modulus':
                    $components['modulus'] = $value;
                    break;
                case 'exponent':
                    $components['publicExponent'] = $value;
                    break;
                case 'p':
                    $components['primes'][1] = $value;
                    break;
                case 'q':
                    $components['primes'][2] = $value;
                    break;
                case 'dp':
                    $components['exponents'][1] = $value;
                    break;
                case 'dq':
                    $components['exponents'][2] = $value;
                    break;
                case 'inverseq':
                    $components['coefficients'][2] = $value;
                    break;
                case 'd':
                    $components['privateExponent'] = $value;
            }
        }

        libxml_use_internal_errors($use_errors);

        return isset($components['modulus']) && isset($components['publicExponent']) ? $components : false;
    }

    /**
     * Convert a private key to the appropriate format.
     *
     * @access public
     * @param \phpseclib\Math\BigInteger $n
     * @param \phpseclib\Math\BigInteger $e
     * @param \phpseclib\Math\BigInteger $d
     * @param array $primes
     * @param array $exponents
     * @param array $coefficients
     * @param string $password optional
     * @return string
     */
    static function savePrivateKey(BigInteger $n, BigInteger $e, BigInteger $d, $primes, $exponents, $coefficients, $password = '')
    {
        if (count($primes) != 2) {
            return false;
        }
        return "<RSAKeyValue>\r\n" .
               '  <Modulus>' . Base64::encode($n->toBytes()) . "</Modulus>\r\n" .
               '  <Exponent>' . Base64::encode($e->toBytes()) . "</Exponent>\r\n" .
               '  <P>' . Base64::encode($primes[1]->toBytes()) . "</P>\r\n" .
               '  <Q>' . Base64::encode($primes[2]->toBytes()) . "</Q>\r\n" .
               '  <DP>' . Base64::encode($exponents[1]->toBytes()) . "</DP>\r\n" .
               '  <DQ>' . Base64::encode($exponents[2]->toBytes()) . "</DQ>\r\n" .
               '  <InverseQ>' . Base64::encode($coefficients[2]->toBytes()) . "</InverseQ>\r\n" .
               '  <D>' . Base64::encode($d->toBytes()) . "</D>\r\n" .
               '</RSAKeyValue>';
    }

    /**
     * Convert a public key to the appropriate format
     *
     * @access public
     * @param \phpseclib\Math\BigInteger $n
     * @param \phpseclib\Math\BigInteger $e
     * @return string
     */
    static function savePublicKey(BigInteger $n, BigInteger $e)
    {
        return "<RSAKeyValue>\r\n" .
               '  <Modulus>' . Base64::encode($n->toBytes()) . "</Modulus>\r\n" .
               '  <Exponent>' . Base64::encode($e->toBytes()) . "</Exponent>\r\n" .
               '</RSAKeyValue>';
    }
}


code:
<?php

/**
 * Random Number Generator
 *
 * PHP version 5
 *
 * Here's a short example of how to use this library:
 * <code>
 * <?php
 *    include 'vendor/autoload.php';
 *
 *    echo bin2hex(\phpseclib\Crypt\Random::string(8));
 * ?>
 * </code>
 *
 * @category  Crypt
 * @package   Random
 * @author    Jim Wigginton <terrafrost@php.net>
 * @copyright 2007 Jim Wigginton
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 * @link      http://phpseclib.sourceforge.net
 */

namespace phpseclib\Crypt;

/**
 * Pure-PHP Random Number Generator
 *
 * @package Random
 * @author  Jim Wigginton <terrafrost@php.net>
 * @access  public
 */
class Random
{
    /**
     * Generate a random string.
     *
     * Although microoptimizations are generally discouraged as they impair readability this function is ripe with
     * microoptimizations because this function has the potential of being called a huge number of times.
     * eg. for RSA key generation.
     *
     * @param int $length
     * @throws \RuntimeException if a symmetric cipher is needed but not loaded
     * @return string
     */
    static function string($length)
    {
        try {
            return \random_bytes($length);
        } catch (\Exception $e) {
            // random_compat will throw an Exception, which in PHP 5 does not implement Throwable
        } catch (\Throwable $e) {
            // If a sufficient source of randomness is unavailable, random_bytes() will throw an
            // object that implements the Throwable interface (Exception, TypeError, Error).
            // We don't actually need to do anything here. The string() method should just continue
            // as normal. Note, however, that if we don't have a sufficient source of randomness for
            // random_bytes(), most of the other calls here will fail too, so we'll end up using
            // the PHP implementation.
        }
        // at this point we have no choice but to use a pure-PHP CSPRNG

        // cascade entropy across multiple PHP instances by fixing the session and collecting all
        // environmental variables, including the previous session data and the current session
        // data.
        //
        // mt_rand seeds itself by looking at the PID and the time, both of which are (relatively)
        // easy to guess at. linux uses mouse clicks, keyboard timings, etc, as entropy sources, but
        // PHP isn't low level to be able to use those as sources and on a web server there's not likely
        // going to be a ton of keyboard or mouse action. web servers do have one thing that we can use
        // however, a ton of people visiting the website. obviously you don't want to base your seeding
        // soley on parameters a potential attacker sends but (1) not everything in $_SERVER is controlled
        // by the user and (2) this isn't just looking at the data sent by the current user - it's based
        // on the data sent by all users. one user requests the page and a hash of their info is saved.
        // another user visits the page and the serialization of their data is utilized along with the
        // server envirnment stuff and a hash of the previous http request data (which itself utilizes
        // a hash of the session data before that). certainly an attacker should be assumed to have
        // full control over his own http requests. he, however, is not going to have control over
        // everyone's http requests.
        static $crypto = false, $v;
        if ($crypto === false) {
            // save old session data
            $old_session_id = session_id();
            $old_use_cookies = ini_get('session.use_cookies');
            $old_session_cache_limiter = session_cache_limiter();
            $_OLD_SESSION = isset($_SESSION) ? $_SESSION : false;
            if ($old_session_id != '') {
                session_write_close();
            }

            session_id(1);
            ini_set('session.use_cookies', 0);
            session_cache_limiter('');
            session_start();

            $v = (isset($_SERVER) ? self::safe_serialize($_SERVER) : '') .
                 (isset($_POST) ? self::safe_serialize($_POST) : '') .
                 (isset($_GET) ? self::safe_serialize($_GET) : '') .
                 (isset($_COOKIE) ? self::safe_serialize($_COOKIE) : '') .
                 self::safe_serialize($GLOBALS) .
                 self::safe_serialize($_SESSION) .
                 self::safe_serialize($_OLD_SESSION);
            $v = $seed = $_SESSION['seed'] = sha1($v, true);
            if (!isset($_SESSION['count'])) {
                $_SESSION['count'] = 0;
            }
            $_SESSION['count']++;

            session_write_close();

            // restore old session data
            if ($old_session_id != '') {
                session_id($old_session_id);
                session_start();
                ini_set('session.use_cookies', $old_use_cookies);
                session_cache_limiter($old_session_cache_limiter);
            } else {
                if ($_OLD_SESSION !== false) {
                    $_SESSION = $_OLD_SESSION;
                    unset($_OLD_SESSION);
                } else {
                    unset($_SESSION);
                }
            }

            // in SSH2 a shared secret and an exchange hash are generated through the key exchange process.
            // the IV client to server is the hash of that "nonce" with the letter A and for the encryption key it's the letter C.
            // if the hash doesn't produce enough a key or an IV that's long enough concat successive hashes of the
            // original hash and the current hash. we'll be emulating that. for more info see the following URL:
            //
            // http://tools.ietf.org/html/rfc4253#section-7.2
            //
            // see the is_string($crypto) part for an example of how to expand the keys
            $key = sha1($seed . 'A', true);
            $iv = sha1($seed . 'C', true);

            // ciphers are used as per the nist.gov link below. also, see this link:
            //
            // http://en.wikipedia.org/wiki/Cryptographically_secure_pseudorandom_number_generator#Designs_based_on_cryptographic_primitives
            switch (true) {
                case class_exists('\phpseclib\Crypt\AES'):
                    $crypto = new AES(Base::MODE_CTR);
                    break;
                case class_exists('\phpseclib\Crypt\Twofish'):
                    $crypto = new Twofish(Base::MODE_CTR);
                    break;
                case class_exists('\phpseclib\Crypt\Blowfish'):
                    $crypto = new Blowfish(Base::MODE_CTR);
                    break;
                case class_exists('\phpseclib\Crypt\TripleDES'):
                    $crypto = new TripleDES(Base::MODE_CTR);
                    break;
                case class_exists('\phpseclib\Crypt\DES'):
                    $crypto = new DES(Base::MODE_CTR);
                    break;
                case class_exists('\phpseclib\Crypt\RC4'):
                    $crypto = new RC4();
                    break;
                default:
                    throw new \RuntimeException(__CLASS__ . ' requires at least one symmetric cipher be loaded');
            }

            $crypto->setKey($key);
            $crypto->setIV($iv);
            $crypto->enableContinuousBuffer();
        }

        //return $crypto->encrypt(str_repeat("\0", $length));

        // the following is based off of ANSI X9.31:
        //
        // http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf
        //
        // OpenSSL uses that same standard for it's random numbers:
        //
        // http://www.opensource.apple.com/source/OpenSSL/OpenSSL-38/openssl/fips-1.0/rand/fips_rand.c
        // (do a search for "ANS X9.31 A.2.4")
        $result = '';
        while (strlen($result) < $length) {
            $i = $crypto->encrypt(microtime()); // strlen(microtime()) == 21
            $r = $crypto->encrypt($i ^ $v); // strlen($v) == 20
            $v = $crypto->encrypt($r ^ $i); // strlen($r) == 20
            $result.= $r;
        }
        return substr($result, 0, $length);
    }

    /**
     * Safely serialize variables
     *
     * If a class has a private __sleep() it'll emit a warning
     *
     * @param mixed $arr
     * @access public
     */
    function safe_serialize(&$arr)
    {
        if (is_object($arr)) {
            return '';
        }
        if (!is_array($arr)) {
            return serialize($arr);
        }
        // prevent circular array recursion
        if (isset($arr['__phpseclib_marker'])) {
            return '';
        }
        $safearr = array();
        $arr['__phpseclib_marker'] = true;
        foreach (array_keys($arr) as $key) {
            // do not recurse on the '__phpseclib_marker' key itself, for smaller memory usage
            if ($key !== '__phpseclib_marker') {
                $safearr[$key] = self::safe_serialize($arr[$key]);
            }
        }
        unset($arr['__phpseclib_marker']);
        return serialize($safearr);
    }
}


code:
<?php

/**
 * Pure-PHP implementation of Rijndael.
 *
 * Uses mcrypt, if available/possible, and an internal implementation, otherwise.
 *
 * PHP version 5
 *
 * If {@link self::setBlockLength() setBlockLength()} isn't called, it'll be assumed to be 128 bits.  If
 * {@link self::setKeyLength() setKeyLength()} isn't called, it'll be calculated from
 * {@link self::setKey() setKey()}.  ie. if the key is 128-bits, the key length will be 128-bits.  If it's
 * 136-bits it'll be null-padded to 192-bits and 192 bits will be the key length until
 * {@link self::setKey() setKey()} is called, again, at which point, it'll be recalculated.
 *
 * Not all Rijndael implementations may support 160-bits or 224-bits as the block length / key length.  mcrypt, for example,
 * does not.  AES, itself, only supports block lengths of 128 and key lengths of 128, 192, and 256.
 * {@link http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf#page=10 Rijndael-ammended.pdf#page=10} defines the
 * algorithm for block lengths of 192 and 256 but not for block lengths / key lengths of 160 and 224.  Indeed, 160 and 224
 * are first defined as valid key / block lengths in
 * {@link http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf#page=44 Rijndael-ammended.pdf#page=44}:
 * Extensions: Other block and Cipher Key lengths.
 * Note: Use of 160/224-bit Keys must be explicitly set by setKeyLength(160) respectively setKeyLength(224).
 *
 * {@internal The variable names are the same as those in
 * {@link http://www.csrc.nist.gov/publications/fips/fips197/fips-197.pdf#page=10 fips-197.pdf#page=10}.}}
 *
 * Here's a short example of how to use this library:
 * <code>
 * <?php
 *    include 'vendor/autoload.php';
 *
 *    $rijndael = new \phpseclib\Crypt\Rijndael();
 *
 *    $rijndael->setKey('abcdefghijklmnop');
 *
 *    $size = 10 * 1024;
 *    $plaintext = '';
 *    for ($i = 0; $i < $size; $i++) {
 *        $plaintext.= 'a';
 *    }
 *
 *    echo $rijndael->decrypt($rijndael->encrypt($plaintext));
 * ?>
 * </code>
 *
 * @category  Crypt
 * @package   Rijndael
 * @author    Jim Wigginton <terrafrost@php.net>
 * @copyright 2008 Jim Wigginton
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 * @link      http://phpseclib.sourceforge.net
 */

namespace phpseclib\Crypt;

/**
 * Pure-PHP implementation of Rijndael.
 *
 * @package Rijndael
 * @author  Jim Wigginton <terrafrost@php.net>
 * @access  public
 */
class Rijndael extends Base
{
    /**
     * The mcrypt specific name of the cipher
     *
     * Mcrypt is useable for 128/192/256-bit $block_size/$key_length. For 160/224 not.
     * \phpseclib\Crypt\Rijndael determines automatically whether mcrypt is useable
     * or not for the current $block_size/$key_length.
     * In case of, $cipher_name_mcrypt will be set dynamically at run time accordingly.
     *
     * @see \phpseclib\Crypt\Base::cipher_name_mcrypt
     * @see \phpseclib\Crypt\Base::engine
     * @see self::isValidEngine()
     * @var string
     * @access private
     */
    var $cipher_name_mcrypt = 'rijndael-128';

    /**
     * The default salt used by setPassword()
     *
     * @see \phpseclib\Crypt\Base::password_default_salt
     * @see \phpseclib\Crypt\Base::setPassword()
     * @var string
     * @access private
     */
    var $password_default_salt = 'phpseclib';

    /**
     * The Key Schedule
     *
     * @see self::_setup()
     * @var array
     * @access private
     */
    var $w;

    /**
     * The Inverse Key Schedule
     *
     * @see self::_setup()
     * @var array
     * @access private
     */
    var $dw;

    /**
     * The Block Length divided by 32
     *
     * @see self::setBlockLength()
     * @var int
     * @access private
     * @internal The max value is 256 / 32 = 8, the min value is 128 / 32 = 4.  Exists in conjunction with $block_size
     *    because the encryption / decryption / key schedule creation requires this number and not $block_size.  We could
     *    derive this from $block_size or vice versa, but that'd mean we'd have to do multiple shift operations, so in lieu
     *    of that, we'll just precompute it once.
     */
    var $Nb = 4;

    /**
     * The Key Length (in bytes)
     *
     * @see self::setKeyLength()
     * @var int
     * @access private
     * @internal The max value is 256 / 8 = 32, the min value is 128 / 8 = 16.  Exists in conjunction with $Nk
     *    because the encryption / decryption / key schedule creation requires this number and not $key_length.  We could
     *    derive this from $key_length or vice versa, but that'd mean we'd have to do multiple shift operations, so in lieu
     *    of that, we'll just precompute it once.
     */
    var $key_length = 16;

    /**
     * The Key Length divided by 32
     *
     * @see self::setKeyLength()
     * @var int
     * @access private
     * @internal The max value is 256 / 32 = 8, the min value is 128 / 32 = 4
     */
    var $Nk = 4;

    /**
     * The Number of Rounds
     *
     * @var int
     * @access private
     * @internal The max value is 14, the min value is 10.
     */
    var $Nr;

    /**
     * Shift offsets
     *
     * @var array
     * @access private
     */
    var $c;

    /**
     * Holds the last used key- and block_size information
     *
     * @var array
     * @access private
     */
    var $kl;

    /**
     * Default Constructor.
     *
     * @param int $mode
     * @access public
     * @throws \InvalidArgumentException if an invalid / unsupported mode is provided
     */
    function __construct($mode)
    {
        if ($mode == self::MODE_STREAM) {
            throw new \InvalidArgumentException('Block ciphers cannot be ran in stream mode');
        }

        parent::__construct($mode);
    }

    /**
     * Sets the key length.
     *
     * Valid key lengths are 128, 160, 192, 224, and 256.
     *
     * Note: phpseclib extends Rijndael (and AES) for using 160- and 224-bit keys but they are officially not defined
     *       and the most (if not all) implementations are not able using 160/224-bit keys but round/pad them up to
     *       192/256 bits as, for example, mcrypt will do.
     *
     *       That said, if you want be compatible with other Rijndael and AES implementations,
     *       you should not setKeyLength(160) or setKeyLength(224).
     *
     * Additional: In case of 160- and 224-bit keys, phpseclib will/can, for that reason, not use
     *             the mcrypt php extension, even if available.
     *             This results then in slower encryption.
     *
     * @access public
     * @throws \LengthException if the key length is invalid
     * @param int $length
     */
    function setKeyLength($length)
    {
        switch ($length) {
            case 128:
            case 160:
            case 192:
            case 224:
            case 256:
                $this->key_length = $length >> 3;
                break;
            default:
                throw new \LengthException('Key size of ' . $length . ' bits is not supported by this algorithm. Only keys of sizes 128, 160, 192, 224 or 256 bits are supported');
        }

        parent::setKeyLength($length);
    }

    /**
     * Sets the key.
     *
     * Rijndael supports five different key lengths
     *
     * @see setKeyLength()
     * @access public
     * @param string $key
     * @throws \LengthException if the key length isn't supported
     */
    function setKey($key)
    {
        switch (strlen($key)) {
            case 16:
            case 20:
            case 24:
            case 28:
            case 32:
                break;
            default:
                throw new \LengthException('Key of size ' . strlen($key) . ' not supported by this algorithm. Only keys of sizes 16, 20, 24, 28 or 32 are supported');
        }

        parent::setKey($key);
    }

    /**
     * Sets the block length
     *
     * Valid block lengths are 128, 160, 192, 224, and 256.
     *
     * @access public
     * @param int $length
     */
    function setBlockLength($length)
    {
        switch ($length) {
            case 128:
            case 160:
            case 192:
            case 224:
            case 256:
                break;
            default:
                throw new \LengthException('Key size of ' . $length . ' bits is not supported by this algorithm. Only keys of sizes 128, 160, 192, 224 or 256 bits are supported');
        }

        $this->Nb = $length >> 5;
        $this->block_size = $length >> 3;
        $this->changed = true;
        $this->_setEngine();
    }

    /**
     * Test for engine validity
     *
     * This is mainly just a wrapper to set things up for \phpseclib\Crypt\Base::isValidEngine()
     *
     * @see \phpseclib\Crypt\Base::__construct()
     * @param int $engine
     * @access public
     * @return bool
     */
    function isValidEngine($engine)
    {
        switch ($engine) {
            case self::ENGINE_OPENSSL:
                if ($this->block_size != 16) {
                    return false;
                }
                $this->cipher_name_openssl_ecb = 'aes-' . ($this->key_length << 3) . '-ecb';
                $this->cipher_name_openssl = 'aes-' . ($this->key_length << 3) . '-' . $this->_openssl_translate_mode();
                break;
            case self::ENGINE_MCRYPT:
                $this->cipher_name_mcrypt = 'rijndael-' . ($this->block_size << 3);
                if ($this->key_length % 8) { // is it a 160/224-bit key?
                    // mcrypt is not usable for them, only for 128/192/256-bit keys
                    return false;
                }
        }

        return parent::isValidEngine($engine);
    }

    /**
     * Encrypts a block
     *
     * @access private
     * @param string $in
     * @return string
     */
    function _encryptBlock($in)
    {
        static $tables;
        if (empty($tables)) {
            $tables = &$this->_getTables();
        }
        $t0   = $tables[0];
        $t1   = $tables[1];
        $t2   = $tables[2];
        $t3   = $tables[3];
        $sbox = $tables[4];

        $state = array();
        $words = unpack('N*', $in);

        $c = $this->c;
        $w = $this->w;
        $Nb = $this->Nb;
        $Nr = $this->Nr;

        // addRoundKey
        $wc = $Nb - 1;
        foreach ($words as $word) {
            $state[] = $word ^ $w[++$wc];
        }

        // fips-197.pdf#page=19, "Figure 5. Pseudo Code for the Cipher", states that this loop has four components -
        // subBytes, shiftRows, mixColumns, and addRoundKey. fips-197.pdf#page=30, "Implementation Suggestions Regarding
        // Various Platforms" suggests that performs enhanced implementations are described in Rijndael-ammended.pdf.
        // Rijndael-ammended.pdf#page=20, "Implementation aspects / 32-bit processor", discusses such an optimization.
        // Unfortunately, the description given there is not quite correct.  Per aes.spec.v316.pdf#page=19 [1],
        // equation (7.4.7) is supposed to use addition instead of subtraction, so we'll do that here, as well.

        // [1] http://fp.gladman.plus.com/cryptography_technology/rijndael/aes.spec.v316.pdf
        $temp = array();
        for ($round = 1; $round < $Nr; ++$round) {
            $i = 0; // $c[0] == 0
            $j = $c[1];
            $k = $c[2];
            $l = $c[3];

            while ($i < $Nb) {
                $temp[$i] = $t0[$state[$i] >> 24 & 0x000000FF] ^
                            $t1[$state[$j] >> 16 & 0x000000FF] ^
                            $t2[$state[$k] >>  8 & 0x000000FF] ^
                            $t3[$state[$l]       & 0x000000FF] ^
                            $w[++$wc];
                ++$i;
                $j = ($j + 1) % $Nb;
                $k = ($k + 1) % $Nb;
                $l = ($l + 1) % $Nb;
            }
            $state = $temp;
        }

        // subWord
        for ($i = 0; $i < $Nb; ++$i) {
            $state[$i] =   $sbox[$state[$i]       & 0x000000FF]        |
                          ($sbox[$state[$i] >>  8 & 0x000000FF] <<  8) |
                          ($sbox[$state[$i] >> 16 & 0x000000FF] << 16) |
                          ($sbox[$state[$i] >> 24 & 0x000000FF] << 24);
        }

        // shiftRows + addRoundKey
        $i = 0; // $c[0] == 0
        $j = $c[1];
        $k = $c[2];
        $l = $c[3];
        while ($i < $Nb) {
            $temp[$i] = ($state[$i] & 0xFF000000) ^
                        ($state[$j] & 0x00FF0000) ^
                        ($state[$k] & 0x0000FF00) ^
                        ($state[$l] & 0x000000FF) ^
                         $w[$i];
            ++$i;
            $j = ($j + 1) % $Nb;
            $k = ($k + 1) % $Nb;
            $l = ($l + 1) % $Nb;
        }

        switch ($Nb) {
            case 8:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4], $temp[5], $temp[6], $temp[7]);
            case 7:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4], $temp[5], $temp[6]);
            case 6:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4], $temp[5]);
            case 5:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4]);
            default:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3]);
        }
    }

    /**
     * Decrypts a block
     *
     * @access private
     * @param string $in
     * @return string
     */
    function _decryptBlock($in)
    {
        static $invtables;
        if (empty($invtables)) {
            $invtables = &$this->_getInvTables();
        }
        $dt0   = $invtables[0];
        $dt1   = $invtables[1];
        $dt2   = $invtables[2];
        $dt3   = $invtables[3];
        $isbox = $invtables[4];

        $state = array();
        $words = unpack('N*', $in);

        $c  = $this->c;
        $dw = $this->dw;
        $Nb = $this->Nb;
        $Nr = $this->Nr;

        // addRoundKey
        $wc = $Nb - 1;
        foreach ($words as $word) {
            $state[] = $word ^ $dw[++$wc];
        }

        $temp = array();
        for ($round = $Nr - 1; $round > 0; --$round) {
            $i = 0; // $c[0] == 0
            $j = $Nb - $c[1];
            $k = $Nb - $c[2];
            $l = $Nb - $c[3];

            while ($i < $Nb) {
                $temp[$i] = $dt0[$state[$i] >> 24 & 0x000000FF] ^
                            $dt1[$state[$j] >> 16 & 0x000000FF] ^
                            $dt2[$state[$k] >>  8 & 0x000000FF] ^
                            $dt3[$state[$l]       & 0x000000FF] ^
                            $dw[++$wc];
                ++$i;
                $j = ($j + 1) % $Nb;
                $k = ($k + 1) % $Nb;
                $l = ($l + 1) % $Nb;
            }
            $state = $temp;
        }

        // invShiftRows + invSubWord + addRoundKey
        $i = 0; // $c[0] == 0
        $j = $Nb - $c[1];
        $k = $Nb - $c[2];
        $l = $Nb - $c[3];

        while ($i < $Nb) {
            $word = ($state[$i] & 0xFF000000) |
                    ($state[$j] & 0x00FF0000) |
                    ($state[$k] & 0x0000FF00) |
                    ($state[$l] & 0x000000FF);

            $temp[$i] = $dw[$i] ^ ($isbox[$word       & 0x000000FF]        |
                                  ($isbox[$word >>  8 & 0x000000FF] <<  8) |
                                  ($isbox[$word >> 16 & 0x000000FF] << 16) |
                                  ($isbox[$word >> 24 & 0x000000FF] << 24));
            ++$i;
            $j = ($j + 1) % $Nb;
            $k = ($k + 1) % $Nb;
            $l = ($l + 1) % $Nb;
        }

        switch ($Nb) {
            case 8:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4], $temp[5], $temp[6], $temp[7]);
            case 7:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4], $temp[5], $temp[6]);
            case 6:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4], $temp[5]);
            case 5:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3], $temp[4]);
            default:
                return pack('N*', $temp[0], $temp[1], $temp[2], $temp[3]);
        }
    }

    /**
     * Setup the key (expansion)
     *
     * @see \phpseclib\Crypt\Base::_setupKey()
     * @access private
     */
    function _setupKey()
    {
        // Each number in $rcon is equal to the previous number multiplied by two in Rijndael's finite field.
        // See http://en.wikipedia.org/wiki/Finite_field_arithmetic#Multiplicative_inverse
        static $rcon = array(0,
            0x01000000, 0x02000000, 0x04000000, 0x08000000, 0x10000000,
            0x20000000, 0x40000000, 0x80000000, 0x1B000000, 0x36000000,
            0x6C000000, 0xD8000000, 0xAB000000, 0x4D000000, 0x9A000000,
            0x2F000000, 0x5E000000, 0xBC000000, 0x63000000, 0xC6000000,
            0x97000000, 0x35000000, 0x6A000000, 0xD4000000, 0xB3000000,
            0x7D000000, 0xFA000000, 0xEF000000, 0xC5000000, 0x91000000
        );

        if (isset($this->kl['key']) && $this->key === $this->kl['key'] && $this->key_length === $this->kl['key_length'] && $this->block_size === $this->kl['block_size']) {
            // already expanded
            return;
        }
        $this->kl = array('key' => $this->key, 'key_length' => $this->key_length, 'block_size' => $this->block_size);

        $this->Nk = $this->key_length >> 2;
        // see Rijndael-ammended.pdf#page=44
        $this->Nr = max($this->Nk, $this->Nb) + 6;

        // shift offsets for Nb = 5, 7 are defined in Rijndael-ammended.pdf#page=44,
        //     "Table 8: Shift offsets in Shiftrow for the alternative block lengths"
        // shift offsets for Nb = 4, 6, 8 are defined in Rijndael-ammended.pdf#page=14,
        //     "Table 2: Shift offsets for different block lengths"
        switch ($this->Nb) {
            case 4:
            case 5:
            case 6:
                $this->c = array(0, 1, 2, 3);
                break;
            case 7:
                $this->c = array(0, 1, 2, 4);
                break;
            case 8:
                $this->c = array(0, 1, 3, 4);
        }

        $w = array_values(unpack('N*words', $this->key));

        $length = $this->Nb * ($this->Nr + 1);
        for ($i = $this->Nk; $i < $length; $i++) {
            $temp = $w[$i - 1];
            if ($i % $this->Nk == 0) {
                // according to <http://php.net/language.types.integer>, "the size of an integer is platform-dependent".
                // on a 32-bit machine, it's 32-bits, and on a 64-bit machine, it's 64-bits. on a 32-bit machine,
                // 0xFFFFFFFF << 8 == 0xFFFFFF00, but on a 64-bit machine, it equals 0xFFFFFFFF00. as such, doing 'and'
                // with 0xFFFFFFFF (or 0xFFFFFF00) on a 32-bit machine is unnecessary, but on a 64-bit machine, it is.
                $temp = (($temp << 8) & 0xFFFFFF00) | (($temp >> 24) & 0x000000FF); // rotWord
                $temp = $this->_subWord($temp) ^ $rcon[$i / $this->Nk];
            } elseif ($this->Nk > 6 && $i % $this->Nk == 4) {
                $temp = $this->_subWord($temp);
            }
            $w[$i] = $w[$i - $this->Nk] ^ $temp;
        }

        // convert the key schedule from a vector of $Nb * ($Nr + 1) length to a matrix with $Nr + 1 rows and $Nb columns
        // and generate the inverse key schedule.  more specifically,
        // according to <http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf#page=23> (section 5.3.3),
        // "The key expansion for the Inverse Cipher is defined as follows:
        //        1. Apply the Key Expansion.
        //        2. Apply InvMixColumn to all Round Keys except the first and the last one."
        // also, see fips-197.pdf#page=27, "5.3.5 Equivalent Inverse Cipher"
        list($dt0, $dt1, $dt2, $dt3) = $this->_getInvTables();
        $temp = $this->w = $this->dw = array();
        for ($i = $row = $col = 0; $i < $length; $i++, $col++) {
            if ($col == $this->Nb) {
                if ($row == 0) {
                    $this->dw[0] = $this->w[0];
                } else {
                    // subWord + invMixColumn + invSubWord = invMixColumn
                    $j = 0;
                    while ($j < $this->Nb) {
                        $dw = $this->_subWord($this->w[$row][$j]);
                        $temp[$j] = $dt0[$dw >> 24 & 0x000000FF] ^
                                    $dt1[$dw >> 16 & 0x000000FF] ^
                                    $dt2[$dw >>  8 & 0x000000FF] ^
                                    $dt3[$dw       & 0x000000FF];
                        $j++;
                    }
                    $this->dw[$row] = $temp;
                }

                $col = 0;
                $row++;
            }
            $this->w[$row][$col] = $w[$i];
        }

        $this->dw[$row] = $this->w[$row];

        // Converting to 1-dim key arrays (both ascending)
        $this->dw = array_reverse($this->dw);
        $w  = array_pop($this->w);
        $dw = array_pop($this->dw);
        foreach ($this->w as $r => $wr) {
            foreach ($wr as $c => $wc) {
                $w[]  = $wc;
                $dw[] = $this->dw[$r][$c];
            }
        }
        $this->w  = $w;
        $this->dw = $dw;
    }

    /**
     * Performs S-Box substitutions
     *
     * @access private
     * @param int $word
     */
    function _subWord($word)
    {
        static $sbox;
        if (empty($sbox)) {
            list(, , , , $sbox) = $this->_getTables();
        }

        return  $sbox[$word       & 0x000000FF]        |
               ($sbox[$word >>  8 & 0x000000FF] <<  8) |
               ($sbox[$word >> 16 & 0x000000FF] << 16) |
               ($sbox[$word >> 24 & 0x000000FF] << 24);
    }

    /**
     * Provides the mixColumns and sboxes tables
     *
     * @see self::_encryptBlock()
     * @see self::_setupInlineCrypt()
     * @see self::_subWord()
     * @access private
     * @return array &$tables
     */
    function &_getTables()
    {
        static $tables;
        if (empty($tables)) {
            // according to <http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf#page=19> (section 5.2.1),
            // precomputed tables can be used in the mixColumns phase. in that example, they're assigned t0...t3, so
            // those are the names we'll use.
            $t3 = array_map('intval', array(
                // with array_map('intval', ...) we ensure we have only int's and not
                // some slower floats converted by php automatically on high values
                0x6363A5C6, 0x7C7C84F8, 0x777799EE, 0x7B7B8DF6, 0xF2F20DFF, 0x6B6BBDD6, 0x6F6FB1DE, 0xC5C55491,
                0x30305060, 0x01010302, 0x6767A9CE, 0x2B2B7D56, 0xFEFE19E7, 0xD7D762B5, 0xABABE64D, 0x76769AEC,
                0xCACA458F, 0x82829D1F, 0xC9C94089, 0x7D7D87FA, 0xFAFA15EF, 0x5959EBB2, 0x4747C98E, 0xF0F00BFB,
                0xADADEC41, 0xD4D467B3, 0xA2A2FD5F, 0xAFAFEA45, 0x9C9CBF23, 0xA4A4F753, 0x727296E4, 0xC0C05B9B,
                0xB7B7C275, 0xFDFD1CE1, 0x9393AE3D, 0x26266A4C, 0x36365A6C, 0x3F3F417E, 0xF7F702F5, 0xCCCC4F83,
                0x34345C68, 0xA5A5F451, 0xE5E534D1, 0xF1F108F9, 0x717193E2, 0xD8D873AB, 0x31315362, 0x15153F2A,
                0x04040C08, 0xC7C75295, 0x23236546, 0xC3C35E9D, 0x18182830, 0x9696A137, 0x05050F0A, 0x9A9AB52F,
                0x0707090E, 0x12123624, 0x80809B1B, 0xE2E23DDF, 0xEBEB26CD, 0x2727694E, 0xB2B2CD7F, 0x75759FEA,
                0x09091B12, 0x83839E1D, 0x2C2C7458, 0x1A1A2E34, 0x1B1B2D36, 0x6E6EB2DC, 0x5A5AEEB4, 0xA0A0FB5B,
                0x5252F6A4, 0x3B3B4D76, 0xD6D661B7, 0xB3B3CE7D, 0x29297B52, 0xE3E33EDD, 0x2F2F715E, 0x84849713,
                0x5353F5A6, 0xD1D168B9, 0x00000000, 0xEDED2CC1, 0x20206040, 0xFCFC1FE3, 0xB1B1C879, 0x5B5BEDB6,
                0x6A6ABED4, 0xCBCB468D, 0xBEBED967, 0x39394B72, 0x4A4ADE94, 0x4C4CD498, 0x5858E8B0, 0xCFCF4A85,
                0xD0D06BBB, 0xEFEF2AC5, 0xAAAAE54F, 0xFBFB16ED, 0x4343C586, 0x4D4DD79A, 0x33335566, 0x85859411,
                0x4545CF8A, 0xF9F910E9, 0x02020604, 0x7F7F81FE, 0x5050F0A0, 0x3C3C4478, 0x9F9FBA25, 0xA8A8E34B,
                0x5151F3A2, 0xA3A3FE5D, 0x4040C080, 0x8F8F8A05, 0x9292AD3F, 0x9D9DBC21, 0x38384870, 0xF5F504F1,
                0xBCBCDF63, 0xB6B6C177, 0xDADA75AF, 0x21216342, 0x10103020, 0xFFFF1AE5, 0xF3F30EFD, 0xD2D26DBF,
                0xCDCD4C81, 0x0C0C1418, 0x13133526, 0xECEC2FC3, 0x5F5FE1BE, 0x9797A235, 0x4444CC88, 0x1717392E,
                0xC4C45793, 0xA7A7F255, 0x7E7E82FC, 0x3D3D477A, 0x6464ACC8, 0x5D5DE7BA, 0x19192B32, 0x737395E6,
                0x6060A0C0, 0x81819819, 0x4F4FD19E, 0xDCDC7FA3, 0x22226644, 0x2A2A7E54, 0x9090AB3B, 0x8888830B,
                0x4646CA8C, 0xEEEE29C7, 0xB8B8D36B, 0x14143C28, 0xDEDE79A7, 0x5E5EE2BC, 0x0B0B1D16, 0xDBDB76AD,
                0xE0E03BDB, 0x32325664, 0x3A3A4E74, 0x0A0A1E14, 0x4949DB92, 0x06060A0C, 0x24246C48, 0x5C5CE4B8,
                0xC2C25D9F, 0xD3D36EBD, 0xACACEF43, 0x6262A6C4, 0x9191A839, 0x9595A431, 0xE4E437D3, 0x79798BF2,
                0xE7E732D5, 0xC8C8438B, 0x3737596E, 0x6D6DB7DA, 0x8D8D8C01, 0xD5D564B1, 0x4E4ED29C, 0xA9A9E049,
                0x6C6CB4D8, 0x5656FAAC, 0xF4F407F3, 0xEAEA25CF, 0x6565AFCA, 0x7A7A8EF4, 0xAEAEE947, 0x08081810,
                0xBABAD56F, 0x787888F0, 0x25256F4A, 0x2E2E725C, 0x1C1C2438, 0xA6A6F157, 0xB4B4C773, 0xC6C65197,
                0xE8E823CB, 0xDDDD7CA1, 0x74749CE8, 0x1F1F213E, 0x4B4BDD96, 0xBDBDDC61, 0x8B8B860D, 0x8A8A850F,
                0x707090E0, 0x3E3E427C, 0xB5B5C471, 0x6666AACC, 0x4848D890, 0x03030506, 0xF6F601F7, 0x0E0E121C,
                0x6161A3C2, 0x35355F6A, 0x5757F9AE, 0xB9B9D069, 0x86869117, 0xC1C15899, 0x1D1D273A, 0x9E9EB927,
                0xE1E138D9, 0xF8F813EB, 0x9898B32B, 0x11113322, 0x6969BBD2, 0xD9D970A9, 0x8E8E8907, 0x9494A733,
                0x9B9BB62D, 0x1E1E223C, 0x87879215, 0xE9E920C9, 0xCECE4987, 0x5555FFAA, 0x28287850, 0xDFDF7AA5,
                0x8C8C8F03, 0xA1A1F859, 0x89898009, 0x0D0D171A, 0xBFBFDA65, 0xE6E631D7, 0x4242C684, 0x6868B8D0,
                0x4141C382, 0x9999B029, 0x2D2D775A, 0x0F0F111E, 0xB0B0CB7B, 0x5454FCA8, 0xBBBBD66D, 0x16163A2C
            ));

            foreach ($t3 as $t3i) {
                $t0[] = (($t3i << 24) & 0xFF000000) | (($t3i >>  8) & 0x00FFFFFF);
                $t1[] = (($t3i << 16) & 0xFFFF0000) | (($t3i >> 16) & 0x0000FFFF);
                $t2[] = (($t3i <<  8) & 0xFFFFFF00) | (($t3i >> 24) & 0x000000FF);
            }

            $tables = array(
                // The Precomputed mixColumns tables t0 - t3
                $t0,
                $t1,
                $t2,
                $t3,
                // The SubByte S-Box
                array(
                    0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, 0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76,
                    0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0,
                    0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC, 0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15,
                    0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, 0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75,
                    0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0, 0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84,
                    0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B, 0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF,
                    0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, 0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8,
                    0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5, 0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2,
                    0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17, 0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73,
                    0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, 0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB,
                    0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C, 0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79,
                    0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9, 0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08,
                    0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, 0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A,
                    0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E, 0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E,
                    0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94, 0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF,
                    0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, 0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16
                )
            );
        }
        return $tables;
    }

    /**
     * Provides the inverse mixColumns and inverse sboxes tables
     *
     * @see self::_decryptBlock()
     * @see self::_setupInlineCrypt()
     * @see self::_setupKey()
     * @access private
     * @return array &$tables
     */
    function &_getInvTables()
    {
        static $tables;
        if (empty($tables)) {
            $dt3 = array_map('intval', array(
                0xF4A75051, 0x4165537E, 0x17A4C31A, 0x275E963A, 0xAB6BCB3B, 0x9D45F11F, 0xFA58ABAC, 0xE303934B,
                0x30FA5520, 0x766DF6AD, 0xCC769188, 0x024C25F5, 0xE5D7FC4F, 0x2ACBD7C5, 0x35448026, 0x62A38FB5,
                0xB15A49DE, 0xBA1B6725, 0xEA0E9845, 0xFEC0E15D, 0x2F7502C3, 0x4CF01281, 0x4697A38D, 0xD3F9C66B,
                0x8F5FE703, 0x929C9515, 0x6D7AEBBF, 0x5259DA95, 0xBE832DD4, 0x7421D358, 0xE0692949, 0xC9C8448E,
                0xC2896A75, 0x8E7978F4, 0x583E6B99, 0xB971DD27, 0xE14FB6BE, 0x88AD17F0, 0x20AC66C9, 0xCE3AB47D,
                0xDF4A1863, 0x1A3182E5, 0x51336097, 0x537F4562, 0x6477E0B1, 0x6BAE84BB, 0x81A01CFE, 0x082B94F9,
                0x48685870, 0x45FD198F, 0xDE6C8794, 0x7BF8B752, 0x73D323AB, 0x4B02E272, 0x1F8F57E3, 0x55AB2A66,
                0xEB2807B2, 0xB5C2032F, 0xC57B9A86, 0x3708A5D3, 0x2887F230, 0xBFA5B223, 0x036ABA02, 0x16825CED,
                0xCF1C2B8A, 0x79B492A7, 0x07F2F0F3, 0x69E2A14E, 0xDAF4CD65, 0x05BED506, 0x34621FD1, 0xA6FE8AC4,
                0x2E539D34, 0xF355A0A2, 0x8AE13205, 0xF6EB75A4, 0x83EC390B, 0x60EFAA40, 0x719F065E, 0x6E1051BD,
                0x218AF93E, 0xDD063D96, 0x3E05AEDD, 0xE6BD464D, 0x548DB591, 0xC45D0571, 0x06D46F04, 0x5015FF60,
                0x98FB2419, 0xBDE997D6, 0x4043CC89, 0xD99E7767, 0xE842BDB0, 0x898B8807, 0x195B38E7, 0xC8EEDB79,
                0x7C0A47A1, 0x420FE97C, 0x841EC9F8, 0x00000000, 0x80868309, 0x2BED4832, 0x1170AC1E, 0x5A724E6C,
                0x0EFFFBFD, 0x8538560F, 0xAED51E3D, 0x2D392736, 0x0FD9640A, 0x5CA62168, 0x5B54D19B, 0x362E3A24,
                0x0A67B10C, 0x57E70F93, 0xEE96D2B4, 0x9B919E1B, 0xC0C54F80, 0xDC20A261, 0x774B695A, 0x121A161C,
                0x93BA0AE2, 0xA02AE5C0, 0x22E0433C, 0x1B171D12, 0x090D0B0E, 0x8BC7ADF2, 0xB6A8B92D, 0x1EA9C814,
                0xF1198557, 0x75074CAF, 0x99DDBBEE, 0x7F60FDA3, 0x01269FF7, 0x72F5BC5C, 0x663BC544, 0xFB7E345B,
                0x4329768B, 0x23C6DCCB, 0xEDFC68B6, 0xE4F163B8, 0x31DCCAD7, 0x63851042, 0x97224013, 0xC6112084,
                0x4A247D85, 0xBB3DF8D2, 0xF93211AE, 0x29A16DC7, 0x9E2F4B1D, 0xB230F3DC, 0x8652EC0D, 0xC1E3D077,
                0xB3166C2B, 0x70B999A9, 0x9448FA11, 0xE9642247, 0xFC8CC4A8, 0xF03F1AA0, 0x7D2CD856, 0x3390EF22,
                0x494EC787, 0x38D1C1D9, 0xCAA2FE8C, 0xD40B3698, 0xF581CFA6, 0x7ADE28A5, 0xB78E26DA, 0xADBFA43F,
                0x3A9DE42C, 0x78920D50, 0x5FCC9B6A, 0x7E466254, 0x8D13C2F6, 0xD8B8E890, 0x39F75E2E, 0xC3AFF582,
                0x5D80BE9F, 0xD0937C69, 0xD52DA96F, 0x2512B3CF, 0xAC993BC8, 0x187DA710, 0x9C636EE8, 0x3BBB7BDB,
                0x267809CD, 0x5918F46E, 0x9AB701EC, 0x4F9AA883, 0x956E65E6, 0xFFE67EAA, 0xBCCF0821, 0x15E8E6EF,
                0xE79BD9BA, 0x6F36CE4A, 0x9F09D4EA, 0xB07CD629, 0xA4B2AF31, 0x3F23312A, 0xA59430C6, 0xA266C035,
                0x4EBC3774, 0x82CAA6FC, 0x90D0B0E0, 0xA7D81533, 0x04984AF1, 0xECDAF741, 0xCD500E7F, 0x91F62F17,
                0x4DD68D76, 0xEFB04D43, 0xAA4D54CC, 0x9604DFE4, 0xD1B5E39E, 0x6A881B4C, 0x2C1FB8C1, 0x65517F46,
                0x5EEA049D, 0x8C355D01, 0x877473FA, 0x0B412EFB, 0x671D5AB3, 0xDBD25292, 0x105633E9, 0xD647136D,
                0xD7618C9A, 0xA10C7A37, 0xF8148E59, 0x133C89EB, 0xA927EECE, 0x61C935B7, 0x1CE5EDE1, 0x47B13C7A,
                0xD2DF599C, 0xF2733F55, 0x14CE7918, 0xC737BF73, 0xF7CDEA53, 0xFDAA5B5F, 0x3D6F14DF, 0x44DB8678,
                0xAFF381CA, 0x68C43EB9, 0x24342C38, 0xA3405FC2, 0x1DC37216, 0xE2250CBC, 0x3C498B28, 0x0D9541FF,
                0xA8017139, 0x0CB3DE08, 0xB4E49CD8, 0x56C19064, 0xCB84617B, 0x32B670D5, 0x6C5C7448, 0xB85742D0
            ));

            foreach ($dt3 as $dt3i) {
                $dt0[] = (($dt3i << 24) & 0xFF000000) | (($dt3i >>  8) & 0x00FFFFFF);
                $dt1[] = (($dt3i << 16) & 0xFFFF0000) | (($dt3i >> 16) & 0x0000FFFF);
                $dt2[] = (($dt3i <<  8) & 0xFFFFFF00) | (($dt3i >> 24) & 0x000000FF);
            };

            $tables = array(
                // The Precomputed inverse mixColumns tables dt0 - dt3
                $dt0,
                $dt1,
                $dt2,
                $dt3,
                // The inverse SubByte S-Box
                array(
                    0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, 0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB,
                    0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB,
                    0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, 0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E,
                    0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, 0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25,
                    0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92,
                    0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, 0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84,
                    0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, 0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06,
                    0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, 0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B,
                    0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, 0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73,
                    0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, 0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E,
                    0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, 0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B,
                    0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, 0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4,
                    0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, 0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F,
                    0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, 0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF,
                    0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0, 0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61,
                    0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, 0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D
                )
            );
        }
        return $tables;
    }

    /**
     * Setup the performance-optimized function for de/encrypt()
     *
     * @see \phpseclib\Crypt\Base::_setupInlineCrypt()
     * @access private
     */
    function _setupInlineCrypt()
    {
        // Note: _setupInlineCrypt() will be called only if $this->changed === true
        // So here we are'nt under the same heavy timing-stress as we are in _de/encryptBlock() or de/encrypt().
        // However...the here generated function- $code, stored as php callback in $this->inline_crypt, must work as fast as even possible.

        $lambda_functions =& self::_getLambdaFunctions();

        // We create max. 10 hi-optimized code for memory reason. Means: For each $key one ultra fast inline-crypt function.
        // (Currently, for Crypt_Rijndael/AES, one generated $lambda_function cost on php5.5@32bit ~80kb unfreeable mem and ~130kb on php5.5@64bit)
        // After that, we'll still create very fast optimized code but not the hi-ultimative code, for each $mode one.
        $gen_hi_opt_code = (bool)(count($lambda_functions) < 10);

        // Generation of a uniqe hash for our generated code
        $code_hash = "Crypt_Rijndael, {$this->mode}, {$this->Nr}, {$this->Nb}";
        if ($gen_hi_opt_code) {
            $code_hash = str_pad($code_hash, 32) . $this->_hashInlineCryptFunction($this->key);
        }

        if (!isset($lambda_functions[$code_hash])) {
            switch (true) {
                case $gen_hi_opt_code:
                    // The hi-optimized $lambda_functions will use the key-words hardcoded for better performance.
                    $w  = $this->w;
                    $dw = $this->dw;
                    $init_encrypt = '';
                    $init_decrypt = '';
                    break;
                default:
                    for ($i = 0, $cw = count($this->w); $i < $cw; ++$i) {
                        $w[]  = '$w['  . $i . ']';
                        $dw[] = '$dw[' . $i . ']';
                    }
                    $init_encrypt = '$w  = $self->w;';
                    $init_decrypt = '$dw = $self->dw;';
            }

            $Nr = $this->Nr;
            $Nb = $this->Nb;
            $c  = $this->c;

            // Generating encrypt code:
            $init_encrypt.= '
                static $tables;
                if (empty($tables)) {
                    $tables = &$self->_getTables();
                }
                $t0   = $tables[0];
                $t1   = $tables[1];
                $t2   = $tables[2];
                $t3   = $tables[3];
                $sbox = $tables[4];
            ';

            $s  = 'e';
            $e  = 's';
            $wc = $Nb - 1;

            // Preround: addRoundKey
            $encrypt_block = '$in = unpack("N*", $in);'."\n";
            for ($i = 0; $i < $Nb; ++$i) {
                $encrypt_block .= '$s'.$i.' = $in['.($i + 1).'] ^ '.$w[++$wc].";\n";
            }

            // Mainrounds: shiftRows + subWord + mixColumns + addRoundKey
            for ($round = 1; $round < $Nr; ++$round) {
                list($s, $e) = array($e, $s);
                for ($i = 0; $i < $Nb; ++$i) {
                    $encrypt_block.=
                        '$'.$e.$i.' =
                        $t0[($'.$s.$i                  .' >> 24) & 0xff] ^
                        $t1[($'.$s.(($i + $c[1]) % $Nb).' >> 16) & 0xff] ^
                        $t2[($'.$s.(($i + $c[2]) % $Nb).' >>  8) & 0xff] ^
                        $t3[ $'.$s.(($i + $c[3]) % $Nb).'        & 0xff] ^
                        '.$w[++$wc].";\n";
                }
            }

            // Finalround: subWord + shiftRows + addRoundKey
            for ($i = 0; $i < $Nb; ++$i) {
                $encrypt_block.=
                    '$'.$e.$i.' =
                     $sbox[ $'.$e.$i.'        & 0xff]        |
                    ($sbox[($'.$e.$i.' >>  8) & 0xff] <<  8) |
                    ($sbox[($'.$e.$i.' >> 16) & 0xff] << 16) |
                    ($sbox[($'.$e.$i.' >> 24) & 0xff] << 24);'."\n";
            }
            $encrypt_block .= '$in = pack("N*"'."\n";
            for ($i = 0; $i < $Nb; ++$i) {
                $encrypt_block.= ',
                    ($'.$e.$i                  .' & '.((int)0xFF000000).') ^
                    ($'.$e.(($i + $c[1]) % $Nb).' &         0x00FF0000   ) ^
                    ($'.$e.(($i + $c[2]) % $Nb).' &         0x0000FF00   ) ^
                    ($'.$e.(($i + $c[3]) % $Nb).' &         0x000000FF   ) ^
                    '.$w[$i]."\n";
            }
            $encrypt_block .= ');';

            // Generating decrypt code:
            $init_decrypt.= '
                static $invtables;
                if (empty($invtables)) {
                    $invtables = &$self->_getInvTables();
                }
                $dt0   = $invtables[0];
                $dt1   = $invtables[1];
                $dt2   = $invtables[2];
                $dt3   = $invtables[3];
                $isbox = $invtables[4];
            ';

            $s  = 'e';
            $e  = 's';
            $wc = $Nb - 1;

            // Preround: addRoundKey
            $decrypt_block = '$in = unpack("N*", $in);'."\n";
            for ($i = 0; $i < $Nb; ++$i) {
                $decrypt_block .= '$s'.$i.' = $in['.($i + 1).'] ^ '.$dw[++$wc].';'."\n";
            }

            // Mainrounds: shiftRows + subWord + mixColumns + addRoundKey
            for ($round = 1; $round < $Nr; ++$round) {
                list($s, $e) = array($e, $s);
                for ($i = 0; $i < $Nb; ++$i) {
                    $decrypt_block.=
                        '$'.$e.$i.' =
                        $dt0[($'.$s.$i                        .' >> 24) & 0xff] ^
                        $dt1[($'.$s.(($Nb + $i - $c[1]) % $Nb).' >> 16) & 0xff] ^
                        $dt2[($'.$s.(($Nb + $i - $c[2]) % $Nb).' >>  8) & 0xff] ^
                        $dt3[ $'.$s.(($Nb + $i - $c[3]) % $Nb).'        & 0xff] ^
                        '.$dw[++$wc].";\n";
                }
            }

            // Finalround: subWord + shiftRows + addRoundKey
            for ($i = 0; $i < $Nb; ++$i) {
                $decrypt_block.=
                    '$'.$e.$i.' =
                     $isbox[ $'.$e.$i.'        & 0xff]        |
                    ($isbox[($'.$e.$i.' >>  8) & 0xff] <<  8) |
                    ($isbox[($'.$e.$i.' >> 16) & 0xff] << 16) |
                    ($isbox[($'.$e.$i.' >> 24) & 0xff] << 24);'."\n";
            }
            $decrypt_block .= '$in = pack("N*"'."\n";
            for ($i = 0; $i < $Nb; ++$i) {
                $decrypt_block.= ',
                    ($'.$e.$i.                        ' & '.((int)0xFF000000).') ^
                    ($'.$e.(($Nb + $i - $c[1]) % $Nb).' &         0x00FF0000   ) ^
                    ($'.$e.(($Nb + $i - $c[2]) % $Nb).' &         0x0000FF00   ) ^
                    ($'.$e.(($Nb + $i - $c[3]) % $Nb).' &         0x000000FF   ) ^
                    '.$dw[$i]."\n";
            }
            $decrypt_block .= ');';

            $lambda_functions[$code_hash] = $this->_createInlineCryptFunction(
                array(
                   'init_crypt'    => '',
                   'init_encrypt'  => $init_encrypt,
                   'init_decrypt'  => $init_decrypt,
                   'encrypt_block' => $encrypt_block,
                   'decrypt_block' => $decrypt_block
                )
            );
        }
        $this->inline_crypt = $lambda_functions[$code_hash];
    }
}


code:
<?php

/**
 * Pure-PHP implementation of Triple DES.
 *
 * Uses mcrypt, if available, and an internal implementation, otherwise.  Operates in the EDE3 mode (encrypt-decrypt-encrypt).
 *
 * PHP version 5
 *
 * Here's a short example of how to use this library:
 *
 * <?php
 *    include 'vendor/autoload.php';
 *
 *    $des = new \phpseclib\Crypt\TripleDES();
 *
 *    $des->setKey('abcdefghijklmnopqrstuvwx');
 *
 *    $size = 10 * 1024;
 *    $plaintext = '';
 *    for ($i = 0; $i < $size; $i++) {
 *        $plaintext.= 'a';
 *    }
 *
 *    echo $des->decrypt($des->encrypt($plaintext));
 * ?>
 *
 *
 * @category  Crypt
 * @package   TripleDES
 * @author    Jim Wigginton <terrafrost@php.net>
 * @copyright 2007 Jim Wigginton
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 * @link      http://phpseclib.sourceforge.net
 */

namespace phpseclib\Crypt;

/**
 * Pure-PHP implementation of Triple DES.
 *
 * @package TripleDES
 * @author  Jim Wigginton <terrafrost@php.net>
 * @access  public
 */
class TripleDES extends DES
{
    /**
     * Encrypt / decrypt using inner chaining
     *
     * Inner chaining is used by SSH-1 and is generally considered to be less secure then outer chaining (self::MODE_CBC3).
     */
    const MODE_3CBC = -2;

    /**
     * Encrypt / decrypt using outer chaining
     *
     * Outer chaining is used by SSH-2 and when the mode is set to \phpseclib\Crypt\Base::MODE_CBC.
     */
    const MODE_CBC3 = Base::MODE_CBC;

    /**
     * Key Length (in bytes)
     *
     * @see \phpseclib\Crypt\TripleDES::setKeyLength()
     * @var int
     * @access private
     */
    var $key_length = 24;

    /**
     * The default salt used by setPassword()
     *
     * @see \phpseclib\Crypt\Base::password_default_salt
     * @see \phpseclib\Crypt\Base::setPassword()
     * @var string
     * @access private
     */
    var $password_default_salt = 'phpseclib';

    /**
     * The mcrypt specific name of the cipher
     *
     * @see \phpseclib\Crypt\DES::cipher_name_mcrypt
     * @see \phpseclib\Crypt\Base::cipher_name_mcrypt
     * @var string
     * @access private
     */
    var $cipher_name_mcrypt = 'tripledes';

    /**
     * Optimizing value while CFB-encrypting
     *
     * @see \phpseclib\Crypt\Base::cfb_init_len
     * @var int
     * @access private
     */
    var $cfb_init_len = 750;

    /**
     * max possible size of $key
     *
     * @see self::setKey()
     * @see \phpseclib\Crypt\DES::setKey()
     * @var string
     * @access private
     */
    var $key_length_max = 24;

    /**
     * Internal flag whether using self::MODE_3CBC or not
     *
     * @var bool
     * @access private
     */
    var $mode_3cbc;

    /**
     * The \phpseclib\Crypt\DES objects
     *
     * Used only if $mode_3cbc === true
     *
     * @var array
     * @access private
     */
    var $des;

    /**
     * Default Constructor.
     *
     * Determines whether or not the mcrypt or OpenSSL extensions should be used.
     *
     * $mode could be:
     *
     * - \phpseclib\Crypt\Base::MODE_ECB
     *
     * - \phpseclib\Crypt\Base::MODE_CBC
     *
     * - \phpseclib\Crypt\Base::MODE_CTR
     *
     * - \phpseclib\Crypt\Base::MODE_CFB
     *
     * - \phpseclib\Crypt\Base::MODE_OFB
     *
     * - \phpseclib\Crypt\TripleDES::MODE_3CB
     *
     * @see \phpseclib\Crypt\DES::__construct()
     * @see \phpseclib\Crypt\Base::__construct()
     * @param int $mode
     * @access public
     */
    function __construct($mode)
    {
        switch ($mode) {
            // In case of self::MODE_3CBC, we init as CRYPT_DES_MODE_CBC
            // and additional flag us internally as 3CBC
            case self::MODE_3CBC:
                parent::__construct(Base::MODE_CBC);
                $this->mode_3cbc = true;

                // This three $des'es will do the 3CBC work (if $key > 64bits)
                $this->des = array(
                    new DES(Base::MODE_CBC),
                    new DES(Base::MODE_CBC),
                    new DES(Base::MODE_CBC),
                );

                // we're going to be doing the padding, ourselves, so disable it in the \phpseclib\Crypt\DES objects
                $this->des[0]->disablePadding();
                $this->des[1]->disablePadding();
                $this->des[2]->disablePadding();
                break;
            // If not 3CBC, we init as usual
            default:
                parent::__construct($mode);
        }
    }

    /**
     * Test for engine validity
     *
     * This is mainly just a wrapper to set things up for \phpseclib\Crypt\Base::isValidEngine()
     *
     * @see \phpseclib\Crypt\Base::__construct()
     * @param int $engine
     * @access public
     * @return bool
     */
    function isValidEngine($engine)
    {
        if ($engine == self::ENGINE_OPENSSL) {
            $this->cipher_name_openssl_ecb = 'des-ede3';
            $mode = $this->_openssl_translate_mode();
            $this->cipher_name_openssl = $mode == 'ecb' ? 'des-ede3' : 'des-ede3-' . $mode;
        }

        return parent::isValidEngine($engine);
    }

    /**
     * Sets the initialization vector.
     *
     * SetIV is not required when \phpseclib\Crypt\Base::MODE_ECB is being used.
     *
     * @see \phpseclib\Crypt\Base::setIV()
     * @access public
     * @param string $iv
     */
    function setIV($iv)
    {
        parent::setIV($iv);
        if ($this->mode_3cbc) {
            $this->des[0]->setIV($iv);
            $this->des[1]->setIV($iv);
            $this->des[2]->setIV($iv);
        }
    }

    /**
     * Sets the key length.
     *
     * Valid key lengths are 128 and 192 bits.
     *
     * If you want to use a 64-bit key use DES.php
     *
     * @see \phpseclib\Crypt\Base:setKeyLength()
     * @access public
     * @throws \LengthException if the key length is invalid
     * @param int $length
     */
    function setKeyLength($length)
    {
        switch ($length) {
            case 128:
            case 192:
                break;
            default:
                throw new \LengthException('Key size of ' . $length . ' bits is not supported by this algorithm. Only keys of sizes 128 or 192 bits are supported');
        }

        parent::setKeyLength($length);
    }

    /**
     * Sets the key.
     *
     * Triple DES can use 128-bit (eg. strlen($key) == 16) or 192-bit (eg. strlen($key) == 24) keys.
     *
     * DES also requires that every eighth bit be a parity bit, however, we'll ignore that.
     *
     * @access public
     * @see \phpseclib\Crypt\DES::setKey()
     * @see \phpseclib\Crypt\Base::setKey()
     * @throws \LengthException if the key length is invalid
     * @param string $key
     */
    function setKey($key)
    {
        if ($this->explicit_key_length !== false && strlen($key) != $this->explicit_key_length) {
            throw new \LengthException('Key length has already been set to ' . $this->explicit_key_length . ' bytes and this key is ' . strlen($key) . ' bytes');
        }

        switch (strlen($key)) {
            case 16:
                $key.= substr($key, 0, 8);
            case 24:
                break;
            default:
                throw new \LengthException('Key of size ' . strlen($key) . ' not supported by this algorithm. Only keys of sizes 16 or 24 are supported');
        }

        // copied from Base::setKey()
        $this->key = $key;
        $this->key_length = strlen($key);
        $this->changed = true;
        $this->_setEngine();

        if ($this->mode_3cbc) {
            $this->des[0]->setKey(substr($key,  0, 8));
            $this->des[1]->setKey(substr($key,  8, 8));
            $this->des[2]->setKey(substr($key, 16, 8));
        }
    }

    /**
     * Encrypts a message.
     *
     * @see \phpseclib\Crypt\Base::encrypt()
     * @access public
     * @param string $plaintext
     * @return string $cipertext
     */
    function encrypt($plaintext)
    {
        // parent::en/decrypt() is able to do all the work for all modes and keylengths,
        // except for: self::MODE_3CBC (inner chaining CBC) with a key > 64bits

        // if the key is smaller then 8, do what we'd normally do
        if ($this->mode_3cbc && strlen($this->key) > 8) {
            return $this->des[2]->encrypt(
                $this->des[1]->decrypt(
                    $this->des[0]->encrypt(
                        $this->_pad($plaintext)
                    )
                )
            );
        }

        return parent::encrypt($plaintext);
    }

    /**
     * Decrypts a message.
     *
     * @see \phpseclib\Crypt\Base::decrypt()
     * @access public
     * @param string $ciphertext
     * @return string $plaintext
     */
    function decrypt($ciphertext)
    {
        if ($this->mode_3cbc && strlen($this->key) > 8) {
            return $this->_unpad(
                $this->des[0]->decrypt(
                    $this->des[1]->encrypt(
                        $this->des[2]->decrypt(
                            str_pad($ciphertext, (strlen($ciphertext) + 7) & 0xFFFFFFF8, "\0")
                        )
                    )
                )
            );
        }

        return parent::decrypt($ciphertext);
    }

    /**
     * Treat consecutive "packets" as if they are a continuous buffer.
     *
     * Say you have a 16-byte plaintext $plaintext.  Using the default behavior, the two following code snippets
     * will yield different outputs:
     *
     *
     *    echo $des->encrypt(substr($plaintext, 0, 8));
     *    echo $des->encrypt(substr($plaintext, 8, 8));
     *
     *
     *    echo $des->encrypt($plaintext);
     *
     *
     * The solution is to enable the continuous buffer.  Although this will resolve the above discrepancy, it creates
     * another, as demonstrated with the following:
     *
     *
     *    $des->encrypt(substr($plaintext, 0, 8));
     *    echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
     *
     *
     *    echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
     *
     *
     * With the continuous buffer disabled, these would yield the same output.  With it enabled, they yield different
     * outputs.  The reason is due to the fact that the initialization vector's change after every encryption /
     * decryption round when the continuous buffer is enabled.  When it's disabled, they remain constant.
     *
     * Put another way, when the continuous buffer is enabled, the state of the \phpseclib\Crypt\DES() object changes after each
     * encryption / decryption round, whereas otherwise, it'd remain constant.  For this reason, it's recommended that
     * continuous buffers not be used.  They do offer better security and are, in fact, sometimes required (SSH uses them),
     * however, they are also less intuitive and more likely to cause you problems.
     *
     * @see \phpseclib\Crypt\Base::enableContinuousBuffer()
     * @see self::disableContinuousBuffer()
     * @access public
     */
    function enableContinuousBuffer()
    {
        parent::enableContinuousBuffer();
        if ($this->mode_3cbc) {
            $this->des[0]->enableContinuousBuffer();
            $this->des[1]->enableContinuousBuffer();
            $this->des[2]->enableContinuousBuffer();
        }
    }

    /**
     * Treat consecutive packets as if they are a discontinuous buffer.
     *
     * The default behavior.
     *
     * @see \phpseclib\Crypt\Base::disableContinuousBuffer()
     * @see self::enableContinuousBuffer()
     * @access public
     */
    function disableContinuousBuffer()
    {
        parent::disableContinuousBuffer();
        if ($this->mode_3cbc) {
            $this->des[0]->disableContinuousBuffer();
            $this->des[1]->disableContinuousBuffer();
            $this->des[2]->disableContinuousBuffer();
        }
    }

    /**
     * Creates the key schedule
     *
     * @see \phpseclib\Crypt\DES::_setupKey()
     * @see \phpseclib\Crypt\Base::_setupKey()
     * @access private
     */
    function _setupKey()
    {
        switch (true) {
            // if $key <= 64bits we configure our internal pure-php cipher engine
            // to act as regular [1]DES, not as 3DES. mcrypt.so::tripledes does the same.
            case strlen($this->key) <= 8:
                $this->des_rounds = 1;
                break;

            // otherwise, if $key > 64bits, we configure our engine to work as 3DES.
            default:
                $this->des_rounds = 3;

                // (only) if 3CBC is used we have, of course, to setup the $des[0-2] keys also separately.
                if ($this->mode_3cbc) {
                    $this->des[0]->_setupKey();
                    $this->des[1]->_setupKey();
                    $this->des[2]->_setupKey();

                    // because $des[0-2] will, now, do all the work we can return here
                    // not need unnecessary stress parent::_setupKey() with our, now unused, $key.
                    return;
                }
        }
        // setup our key
        parent::_setupKey();
    }

    /**
     * Sets the internal crypt engine
     *
     * @see \phpseclib\Crypt\Base::__construct()
     * @see \phpseclib\Crypt\Base::setPreferredEngine()
     * @param int $engine
     * @access public
     * @return int
     */
    function setPreferredEngine($engine)
    {
        if ($this->mode_3cbc) {
            $this->des[0]->setPreferredEngine($engine);
            $this->des[1]->setPreferredEngine($engine);
            $this->des[2]->setPreferredEngine($engine);
        }

        return parent::setPreferredEngine($engine);
    }
}