/vendor/phpseclib/Crypt/RSA.php

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<?php
/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */

namespace PHPSecLib;

/**
 * Pure-PHP PKCS#1 (v2.1) compliant implementation of RSA.
 *
 * PHP versions 4 and 5
 *
 * Here's an example of how to encrypt and decrypt text with this library:
 * <code>
 * <?php
 *    include 'Crypt/RSA.php';
 *
 *    $rsa = new Crypt_RSA();
 *    extract($rsa->createKey());
 *
 *    $plaintext = 'terrafrost';
 *
 *    $rsa->loadKey($privatekey);
 *    $ciphertext = $rsa->encrypt($plaintext);
 *
 *    $rsa->loadKey($publickey);
 *    echo $rsa->decrypt($ciphertext);
 * ?>
 * </code>
 *
 * Here's an example of how to create signatures and verify signatures with this library:
 * <code>
 * <?php
 *    include 'Crypt/RSA.php';
 *
 *    $rsa = new Crypt_RSA();
 *    extract($rsa->createKey());
 *
 *    $plaintext = 'terrafrost';
 *
 *    $rsa->loadKey($privatekey);
 *    $signature = $rsa->sign($plaintext);
 *
 *    $rsa->loadKey($publickey);
 *    echo $rsa->verify($plaintext, $signature) ? 'verified' : 'unverified';
 * ?>
 * </code>
 *
 * LICENSE: Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @category  Crypt
 * @package   Crypt_RSA
 * @author    Jim Wigginton <terrafrost@php.net>
 * @copyright MMIX Jim Wigginton
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 * @link      http://phpseclib.sourceforge.net
 */

use \PHPSecLib\Crypt\Random;
use \PHPSecLib\Math\BigInteger;

/**#@+
 * @access public
 * @see Crypt_RSA::encrypt()
 * @see Crypt_RSA::decrypt()
 */
/**
 * Use {@link http://en.wikipedia.org/wiki/Optimal_Asymmetric_Encryption_Padding Optimal Asymmetric Encryption Padding}
 * (OAEP) for encryption / decryption.
 *
 * Uses sha1 by default.
 *
 * @see Crypt_RSA::setHash()
 * @see Crypt_RSA::setMGFHash()
 */
define('CRYPT_RSA_ENCRYPTION_OAEP',  1);
/**
 * Use PKCS#1 padding.
 *
 * Although CRYPT_RSA_ENCRYPTION_OAEP offers more security, including PKCS#1 padding is necessary for purposes of backwards
 * compatibility with protocols (like SSH-1) written before OAEP's introduction.
 */
define('CRYPT_RSA_ENCRYPTION_PKCS1', 2);
/**#@-*/

/**#@+
 * @access public
 * @see Crypt_RSA::sign()
 * @see Crypt_RSA::verify()
 * @see Crypt_RSA::setHash()
 */
/**
 * Use the Probabilistic Signature Scheme for signing
 *
 * Uses sha1 by default.
 *
 * @see Crypt_RSA::setSaltLength()
 * @see Crypt_RSA::setMGFHash()
 */
define('CRYPT_RSA_SIGNATURE_PSS',  1);
/**
 * Use the PKCS#1 scheme by default.
 *
 * Although CRYPT_RSA_SIGNATURE_PSS offers more security, including PKCS#1 signing is necessary for purposes of backwards
 * compatibility with protocols (like SSH-2) written before PSS's introduction.
 */
define('CRYPT_RSA_SIGNATURE_PKCS1', 2);
/**#@-*/

/**#@+
 * @access private
 * @see Crypt_RSA::createKey()
 */
/**
 * ASN1 Integer
 */
define('CRYPT_RSA_ASN1_INTEGER',     2);
/**
 * ASN1 Bit String
 */
define('CRYPT_RSA_ASN1_BITSTRING',   3);
/**
 * ASN1 Octet String
 */
define('CRYPT_RSA_ASN1_OCTETSTRING', 4);
/**
 * ASN1 Object Identifier
 */
define('CRYPT_RSA_ASN1_OBJECT',      6);
/**
 * ASN1 Sequence (with the constucted bit set)
 */
define('CRYPT_RSA_ASN1_SEQUENCE',   48);
/**#@-*/

/**#@+
 * @access private
 * @see Crypt_RSA::__construct()
 */
/**
 * To use the pure-PHP implementation
 */
define('CRYPT_RSA_MODE_INTERNAL', 1);
/**
 * To use the OpenSSL library
 *
 * (if enabled; otherwise, the internal implementation will be used)
 */
define('CRYPT_RSA_MODE_OPENSSL', 2);
/**#@-*/

/**
 * Default openSSL configuration file.
 */
define('CRYPT_RSA_OPENSSL_CONFIG', dirname(__FILE__) . '/../openssl.cnf');

/**#@+
 * @access public
 * @see Crypt_RSA::createKey()
 * @see Crypt_RSA::setPrivateKeyFormat()
 */
/**
 * PKCS#1 formatted private key
 *
 * Used by OpenSSH
 */
define('CRYPT_RSA_PRIVATE_FORMAT_PKCS1', 0);
/**
 * PuTTY formatted private key
 */
define('CRYPT_RSA_PRIVATE_FORMAT_PUTTY', 1);
/**
 * XML formatted private key
 */
define('CRYPT_RSA_PRIVATE_FORMAT_XML', 2);
/**
 * PKCS#8 formatted private key
 */
define('CRYPT_RSA_PRIVATE_FORMAT_PKCS8', 3);
/**#@-*/

/**#@+
 * @access public
 * @see Crypt_RSA::createKey()
 * @see Crypt_RSA::setPublicKeyFormat()
 */
/**
 * Raw public key
 *
 * 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
 */
define('CRYPT_RSA_PUBLIC_FORMAT_RAW', 3);
/**
 * PKCS#1 formatted public key (raw)
 *
 * Used by File/X509.php
 *
 * Has the following header:
 *
 * -----BEGIN RSA PUBLIC KEY-----
 *
 * Analogous to ssh-keygen's pem format (as specified by -m)
 */
define('CRYPT_RSA_PUBLIC_FORMAT_PKCS1', 4);
define('CRYPT_RSA_PUBLIC_FORMAT_PKCS1_RAW', 4);
/**
 * XML formatted public key
 */
define('CRYPT_RSA_PUBLIC_FORMAT_XML', 5);
/**
 * OpenSSH formatted public key
 *
 * Place in $HOME/.ssh/authorized_keys
 */
define('CRYPT_RSA_PUBLIC_FORMAT_OPENSSH', 6);
/**
 * PKCS#1 formatted public key (encapsulated)
 *
 * 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)
 */
define('CRYPT_RSA_PUBLIC_FORMAT_PKCS8', 7);
/**#@-*/

/**
 * Pure-PHP PKCS#1 compliant implementation of RSA.
 *
 * @package Crypt_RSA
 * @author  Jim Wigginton <terrafrost@php.net>
 * @access  public
 */
class Crypt_RSA
{
    /**
     * Precomputed Zero
     *
     * @var Array
     * @access private
     */
    var $zero;

    /**
     * Precomputed One
     *
     * @var Array
     * @access private
     */
    var $one;

    /**
     * Private Key Format
     *
     * @var Integer
     * @access private
     */
    var $privateKeyFormat = CRYPT_RSA_PRIVATE_FORMAT_PKCS1;

    /**
     * Public Key Format
     *
     * @var Integer
     * @access public
     */
    var $publicKeyFormat = CRYPT_RSA_PUBLIC_FORMAT_PKCS8;

    /**
     * Modulus (ie. n)
     *
     * @var \phpseclib\Math\BigInteger
     * @access private
     */
    var $modulus;

    /**
     * Modulus length
     *
     * @var \phpseclib\Math\BigInteger
     * @access private
     */
    var $k;

    /**
     * Exponent (ie. e or d)
     *
     * @var \phpseclib\Math\BigInteger
     * @access private
     */
    var $exponent;

    /**
     * Primes for Chinese Remainder Theorem (ie. p and q)
     *
     * @var Array
     * @access private
     */
    var $primes;

    /**
     * Exponents for Chinese Remainder Theorem (ie. dP and dQ)
     *
     * @var Array
     * @access private
     */
    var $exponents;

    /**
     * Coefficients for Chinese Remainder Theorem (ie. qInv)
     *
     * @var Array
     * @access private
     */
    var $coefficients;

    /**
     * Hash name
     *
     * @var String
     * @access private
     */
    var $hashName;

    /**
     * Hash function
     *
     * @var Crypt_Hash
     * @access private
     */
    var $hash;

    /**
     * Length of hash function output
     *
     * @var Integer
     * @access private
     */
    var $hLen;

    /**
     * Length of salt
     *
     * @var Integer
     * @access private
     */
    var $sLen;

    /**
     * Hash function for the Mask Generation Function
     *
     * @var Crypt_Hash
     * @access private
     */
    var $mgfHash;

    /**
     * Length of MGF hash function output
     *
     * @var Integer
     * @access private
     */
    var $mgfHLen;

    /**
     * Encryption mode
     *
     * @var Integer
     * @access private
     */
    var $encryptionMode = CRYPT_RSA_ENCRYPTION_OAEP;

    /**
     * Signature mode
     *
     * @var Integer
     * @access private
     */
    var $signatureMode = CRYPT_RSA_SIGNATURE_PSS;

    /**
     * Public Exponent
     *
     * @var Mixed
     * @access private
     */
    var $publicExponent = false;

    /**
     * Password
     *
     * @var String
     * @access private
     */
    var $password = false;

    /**
     * Components
     *
     * For use with parsing XML formatted keys.  PHP's XML Parser functions use utilized - instead of PHP's DOM functions -
     * because PHP's XML Parser functions work on PHP4 whereas PHP's DOM functions - although surperior - don't.
     *
     * @see Crypt_RSA::_start_element_handler()
     * @var Array
     * @access private
     */
    var $components = array();

    /**
     * Current String
     *
     * For use with parsing XML formatted keys.
     *
     * @see Crypt_RSA::_character_handler()
     * @see Crypt_RSA::_stop_element_handler()
     * @var Mixed
     * @access private
     */
    var $current;

    /**
     * OpenSSL configuration file name.
     *
     * Set to null to use system configuration file.
     * @see Crypt_RSA::createKey()
     * @var Mixed
     * @Access public
     */
    var $configFile;

    /**
     * Public key comment field.
     *
     * @var String
     * @access private
     */
    var $comment = 'phpseclib-generated-key';

    /**
     * The constructor
     *
     * If you want to make use of the openssl extension, you'll need to set the mode manually, yourself.  The reason
     * Crypt_RSA doesn't do it is because OpenSSL doesn't fail gracefully.  openssl_pkey_new(), in particular, requires
     * openssl.cnf be present somewhere and, unfortunately, the only real way to find out is too late.
     *
     * @return Crypt_RSA
     * @access public
     */
    function __construct()
    {
        $this->configFile = CRYPT_RSA_OPENSSL_CONFIG;

        if ( !defined('CRYPT_RSA_MODE') ) {
            switch (true) {
                // Math/BigInteger's openssl requirements are a little less stringent than Crypt/RSA's. in particular,
                // Math/BigInteger doesn't require an openssl.cfg file whereas Crypt/RSA does. so if Math/BigInteger
                // can't use OpenSSL it can be pretty trivially assumed, then, that Crypt/RSA can't either.
                case defined('MATH_BIGINTEGER_OPENSSL_DISABLE'):
                    define('CRYPT_RSA_MODE', CRYPT_RSA_MODE_INTERNAL);
                    break;
                // openssl_pkey_get_details - which is used in the only place Crypt/RSA.php uses OpenSSL - was introduced in PHP 5.2.0
                case !function_exists('openssl_pkey_get_details'):
                    define('CRYPT_RSA_MODE', CRYPT_RSA_MODE_INTERNAL);
                    break;
                case extension_loaded('openssl') && version_compare(PHP_VERSION, '4.2.0', '>=') && file_exists($this->configFile):
                    // some versions of XAMPP have mismatched versions of OpenSSL which causes it not to work
                    ob_start();
                    @phpinfo();
                    $content = ob_get_contents();
                    ob_end_clean();

                    preg_match_all('#OpenSSL (Header|Library) Version(.*)#im', $content, $matches);

                    $versions = array();
                    if (!empty($matches[1])) {
                       for ($i = 0; $i < count($matches[1]); $i++) {
                          $versions[$matches[1][$i]] = trim(str_replace('=>', '', strip_tags($matches[2][$i])));
                       }
                    }

                    // it doesn't appear that OpenSSL versions were reported upon until PHP 5.3+
                    switch (true) {
                        case !isset($versions['Header']):
                        case !isset($versions['Library']):
                        case $versions['Header'] == $versions['Library']:
                            define('CRYPT_RSA_MODE', CRYPT_RSA_MODE_OPENSSL);
                            break;
                        default:
                            define('CRYPT_RSA_MODE', CRYPT_RSA_MODE_INTERNAL);
                            define('MATH_BIGINTEGER_OPENSSL_DISABLE', true);
                    }
                    break;
                default:
                    define('CRYPT_RSA_MODE', CRYPT_RSA_MODE_INTERNAL);
            }
        }

        $this->zero = new BigInteger();
        $this->one = new BigInteger(1);

        $this->hash = new Crypt_Hash('sha1');
        $this->hLen = $this->hash->getLength();
        $this->hashName = 'sha1';
        $this->mgfHash = new Crypt_Hash('sha1');
        $this->mgfHLen = $this->mgfHash->getLength();
    }

    /**
     * Create public / private key pair
     *
     * Returns an array with the following three elements:
     *  - 'privatekey': The private key.
     *  - 'publickey':  The public key.
     *  - 'partialkey': A partially computed key (if the execution time exceeded $timeout).
     *                  Will need to be passed back to Crypt_RSA::createKey() as the third parameter for further processing.
     *
     * @access public
     * @param optional Integer $bits
     * @param optional Integer $timeout
     * @param optional array $p
     */
    function createKey($bits = 1024, $timeout = false, $partial = array())
    {
        if (!defined('CRYPT_RSA_EXPONENT')) {
            // http://en.wikipedia.org/wiki/65537_%28number%29
            define('CRYPT_RSA_EXPONENT', '65537');
        }
        // per <http://cseweb.ucsd.edu/~hovav/dist/survey.pdf#page=5>, this number ought not result in primes smaller
        // than 256 bits. as a consequence if the key you're trying to create is 1024 bits and you've set CRYPT_RSA_SMALLEST_PRIME
        // to 384 bits then you're going to get a 384 bit prime and a 640 bit prime (384 + 1024 % 384). at least if
        // CRYPT_RSA_MODE is set to CRYPT_RSA_MODE_INTERNAL. if CRYPT_RSA_MODE is set to CRYPT_RSA_MODE_OPENSSL then
        // CRYPT_RSA_SMALLEST_PRIME is ignored (ie. multi-prime RSA support is more intended as a way to speed up RSA key
        // generation when there's a chance neither gmp nor OpenSSL are installed)
        if (!defined('CRYPT_RSA_SMALLEST_PRIME')) {
            define('CRYPT_RSA_SMALLEST_PRIME', 4096);
        }

        // OpenSSL uses 65537 as the exponent and requires RSA keys be 384 bits minimum
        if ( CRYPT_RSA_MODE == CRYPT_RSA_MODE_OPENSSL && $bits >= 384 && CRYPT_RSA_EXPONENT == 65537) {
            $config = array();
            if (isset($this->configFile)) {
                $config['config'] = $this->configFile;
            }
            $rsa = openssl_pkey_new(array('private_key_bits' => $bits) + $config);
            openssl_pkey_export($rsa, $privatekey, null, $config);
            $publickey = openssl_pkey_get_details($rsa);
            $publickey = $publickey['key'];

            $privatekey = call_user_func_array(array($this, '_convertPrivateKey'), array_values($this->_parseKey($privatekey, CRYPT_RSA_PRIVATE_FORMAT_PKCS1)));
            $publickey = call_user_func_array(array($this, '_convertPublicKey'), array_values($this->_parseKey($publickey, CRYPT_RSA_PUBLIC_FORMAT_PKCS1)));

            // clear the buffer of error strings stemming from a minimalistic openssl.cnf
            while (openssl_error_string() !== false);

            return array(
                'privatekey' => $privatekey,
                'publickey' => $publickey,
                'partialkey' => false
            );
        }

        static $e;
        if (!isset($e)) {
            $e = new BigInteger(CRYPT_RSA_EXPONENT);
        }

        extract($this->_generateMinMax($bits));
        $absoluteMin = $min;
        $temp = $bits >> 1; // divide by two to see how many bits P and Q would be
        if ($temp > CRYPT_RSA_SMALLEST_PRIME) {
            $num_primes = floor($bits / CRYPT_RSA_SMALLEST_PRIME);
            $temp = CRYPT_RSA_SMALLEST_PRIME;
        } else {
            $num_primes = 2;
        }
        extract($this->_generateMinMax($temp + $bits % $temp));
        $finalMax = $max;
        extract($this->_generateMinMax($temp));

        $generator = new BigInteger();

        $n = $this->one->copy();
        if (!empty($partial)) {
            extract(unserialize($partial));
        } else {
            $exponents = $coefficients = $primes = array();
            $lcm = array(
                'top' => $this->one->copy(),
                'bottom' => false
            );
        }

        $start = time();
        $i0 = count($primes) + 1;

        do {
            for ($i = $i0; $i <= $num_primes; $i++) {
                if ($timeout !== false) {
                    $timeout-= time() - $start;
                    $start = time();
                    if ($timeout <= 0) {
                        return array(
                            'privatekey' => '',
                            'publickey'  => '',
                            'partialkey' => serialize(array(
                                'primes' => $primes,
                                'coefficients' => $coefficients,
                                'lcm' => $lcm,
                                'exponents' => $exponents
                            ))
                        );
                    }
                }

                if ($i == $num_primes) {
                    list($min, $temp) = $absoluteMin->divide($n);
                    if (!$temp->equals($this->zero)) {
                        $min = $min->add($this->one); // ie. ceil()
                    }
                    $primes[$i] = $generator->randomPrime($min, $finalMax, $timeout);
                } else {
                    $primes[$i] = $generator->randomPrime($min, $max, $timeout);
                }

                if ($primes[$i] === false) { // if we've reached the timeout
                    if (count($primes) > 1) {
                        $partialkey = '';
                    } else {
                        array_pop($primes);
                        $partialkey = serialize(array(
                            'primes' => $primes,
                            'coefficients' => $coefficients,
                            'lcm' => $lcm,
                            'exponents' => $exponents
                        ));
                    }

                    return array(
                        'privatekey' => '',
                        'publickey'  => '',
                        'partialkey' => $partialkey
                    );
                }

                // the first coefficient is calculated differently from the rest
                // ie. instead of being $primes[1]->modInverse($primes[2]), it's $primes[2]->modInverse($primes[1])
                if ($i > 2) {
                    $coefficients[$i] = $n->modInverse($primes[$i]);
                }

                $n = $n->multiply($primes[$i]);

                $temp = $primes[$i]->subtract($this->one);

                // textbook RSA implementations use Euler's totient function instead of the least common multiple.
                // see http://en.wikipedia.org/wiki/Euler%27s_totient_function
                $lcm['top'] = $lcm['top']->multiply($temp);
                $lcm['bottom'] = $lcm['bottom'] === false ? $temp : $lcm['bottom']->gcd($temp);

                $exponents[$i] = $e->modInverse($temp);
            }

            list($temp) = $lcm['top']->divide($lcm['bottom']);
            $gcd = $temp->gcd($e);
            $i0 = 1;
        } while (!$gcd->equals($this->one));

        $d = $e->modInverse($temp);

        $coefficients[2] = $primes[2]->modInverse($primes[1]);

        // from <http://tools.ietf.org/html/rfc3447#appendix-A.1.2>:
        // RSAPrivateKey ::= SEQUENCE {
        //     version           Version,
        //     modulus           INTEGER,  -- n
        //     publicExponent    INTEGER,  -- e
        //     privateExponent   INTEGER,  -- d
        //     prime1            INTEGER,  -- p
        //     prime2            INTEGER,  -- q
        //     exponent1         INTEGER,  -- d mod (p-1)
        //     exponent2         INTEGER,  -- d mod (q-1)
        //     coefficient       INTEGER,  -- (inverse of q) mod p
        //     otherPrimeInfos   OtherPrimeInfos OPTIONAL
        // }

        return array(
            'privatekey' => $this->_convertPrivateKey($n, $e, $d, $primes, $exponents, $coefficients),
            'publickey'  => $this->_convertPublicKey($n, $e),
            'partialkey' => false
        );
    }

    /**
     * Convert a private key to the appropriate format.
     *
     * @access private
     * @see setPrivateKeyFormat()
     * @param String $RSAPrivateKey
     * @return String
     */
    function _convertPrivateKey($n, $e, $d, $primes, $exponents, $coefficients)
    {
        $signed = $this->privateKeyFormat != CRYPT_RSA_PRIVATE_FORMAT_XML;
        $num_primes = count($primes);
        $raw = array(
            'version' => $num_primes == 2 ? chr(0) : chr(1), // two-prime vs. multi
            'modulus' => $n->toBytes($signed),
            'publicExponent' => $e->toBytes($signed),
            'privateExponent' => $d->toBytes($signed),
            'prime1' => $primes[1]->toBytes($signed),
            'prime2' => $primes[2]->toBytes($signed),
            'exponent1' => $exponents[1]->toBytes($signed),
            'exponent2' => $exponents[2]->toBytes($signed),
            'coefficient' => $coefficients[2]->toBytes($signed)
        );

        // if the format in question does not support multi-prime rsa and multi-prime rsa was used,
        // call _convertPublicKey() instead.
        switch ($this->privateKeyFormat) {
            case CRYPT_RSA_PRIVATE_FORMAT_XML:
                if ($num_primes != 2) {
                    return false;
                }
                return "<RSAKeyValue>\r\n" .
                       '  <Modulus>' . base64_encode($raw['modulus']) . "</Modulus>\r\n" .
                       '  <Exponent>' . base64_encode($raw['publicExponent']) . "</Exponent>\r\n" .
                       '  <P>' . base64_encode($raw['prime1']) . "</P>\r\n" .
                       '  <Q>' . base64_encode($raw['prime2']) . "</Q>\r\n" .
                       '  <DP>' . base64_encode($raw['exponent1']) . "</DP>\r\n" .
                       '  <DQ>' . base64_encode($raw['exponent2']) . "</DQ>\r\n" .
                       '  <InverseQ>' . base64_encode($raw['coefficient']) . "</InverseQ>\r\n" .
                       '  <D>' . base64_encode($raw['privateExponent']) . "</D>\r\n" .
                       '</RSAKeyValue>';
                break;
            case CRYPT_RSA_PRIVATE_FORMAT_PUTTY:
                if ($num_primes != 2) {
                    return false;
                }
                $key = "PuTTY-User-Key-File-2: ssh-rsa\r\nEncryption: ";
                $encryption = (!empty($this->password) || is_string($this->password)) ? 'aes256-cbc' : 'none';
                $key.= $encryption;
                $key.= "\r\nComment: " . $this->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), $encryption,
                    strlen($this->comment), $this->comment, strlen($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']), $raw['coefficient']
                );
                if (empty($this->password) && !is_string($this->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);
                    $sequence = 0;
                    $symkey = '';
                    while (strlen($symkey) < 32) {
                        $temp = pack('Na*', $sequence++, $this->password);
                        $symkey.= pack('H*', sha1($temp));
                    }
                    $symkey = substr($symkey, 0, 32);
                    $crypto = new Crypt_AES();

                    $crypto->setKey($symkey);
                    $crypto->disablePadding();
                    $private = $crypto->encrypt($private);
                    $hashkey = 'putty-private-key-file-mac-key' . $this->password;
                }

                $private = base64_encode($private);
                $key.= 'Private-Lines: ' . ((strlen($private) + 63) >> 6) . "\r\n";
                $key.= chunk_split($private, 64);
                $hash = new Crypt_Hash('sha1');
                $hash->setKey(pack('H*', sha1($hashkey)));
                $key.= 'Private-MAC: ' . bin2hex($hash->hash($source)) . "\r\n";

                return $key;
            default: // eg. CRYPT_RSA_PRIVATE_FORMAT_PKCS1
                $components = array();
                foreach ($raw as $name => $value) {
                    $components[$name] = pack('Ca*a*', CRYPT_RSA_ASN1_INTEGER, $this->_encodeLength(strlen($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*', CRYPT_RSA_ASN1_INTEGER, $this->_encodeLength(strlen($primes[$i]->toBytes(true))), $primes[$i]->toBytes(true));
                        $OtherPrimeInfo.= pack('Ca*a*', CRYPT_RSA_ASN1_INTEGER, $this->_encodeLength(strlen($exponents[$i]->toBytes(true))), $exponents[$i]->toBytes(true));
                        $OtherPrimeInfo.= pack('Ca*a*', CRYPT_RSA_ASN1_INTEGER, $this->_encodeLength(strlen($coefficients[$i]->toBytes(true))), $coefficients[$i]->toBytes(true));
                        $OtherPrimeInfos.= pack('Ca*a*', CRYPT_RSA_ASN1_SEQUENCE, $this->_encodeLength(strlen($OtherPrimeInfo)), $OtherPrimeInfo);
                    }
                    $RSAPrivateKey.= pack('Ca*a*', CRYPT_RSA_ASN1_SEQUENCE, $this->_encodeLength(strlen($OtherPrimeInfos)), $OtherPrimeInfos);
                }

                $RSAPrivateKey = pack('Ca*a*', CRYPT_RSA_ASN1_SEQUENCE, $this->_encodeLength(strlen($RSAPrivateKey)), $RSAPrivateKey);

                if ($this->privateKeyFormat == CRYPT_RSA_PRIVATE_FORMAT_PKCS8) {
                    $rsaOID = pack('H*', '300d06092a864886f70d0101010500'); // hex version of MA0GCSqGSIb3DQEBAQUA
                    $RSAPrivateKey = pack('Ca*a*Ca*a*',
                        CRYPT_RSA_ASN1_INTEGER, "\01\00", $rsaOID, 4, $this->_encodeLength(strlen($RSAPrivateKey)), $RSAPrivateKey
                    );
                    $RSAPrivateKey = pack('Ca*a*', CRYPT_RSA_ASN1_SEQUENCE, $this->_encodeLength(strlen($RSAPrivateKey)), $RSAPrivateKey);
                    if (!empty($this->password) || is_string($this->password)) {
                        $salt = Random::string(8);
                        $iterationCount = 2048;

                        $crypto = new Crypt_DES();
                        $crypto->setPassword($this->password, 'pbkdf1', 'md5', $salt, $iterationCount);
                        $RSAPrivateKey = $crypto->encrypt($RSAPrivateKey);

                        $parameters = pack('Ca*a*Ca*N',
                            CRYPT_RSA_ASN1_OCTETSTRING, $this->_encodeLength(strlen($salt)), $salt,
                            CRYPT_RSA_ASN1_INTEGER, $this->_encodeLength(4), $iterationCount
                        );
                        $pbeWithMD5AndDES_CBC = "\x2a\x86\x48\x86\xf7\x0d\x01\x05\x03";

                        $encryptionAlgorithm = pack('Ca*a*Ca*a*',
                            CRYPT_RSA_ASN1_OBJECT, $this->_encodeLength(strlen($pbeWithMD5AndDES_CBC)), $pbeWithMD5AndDES_CBC,
                            CRYPT_RSA_ASN1_SEQUENCE, $this->_encodeLength(strlen($parameters)), $parameters
                        );

                        $RSAPrivateKey = pack('Ca*a*Ca*a*',
                            CRYPT_RSA_ASN1_SEQUENCE, $this->_encodeLength(strlen($encryptionAlgorithm)), $encryptionAlgorithm,
                            CRYPT_RSA_ASN1_OCTETSTRING, $this->_encodeLength(strlen($RSAPrivateKey)), $RSAPrivateKey
                        );

                        $RSAPrivateKey = pack('Ca*a*', CRYPT_RSA_ASN1_SEQUENCE, $this->_encodeLength(strlen($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;
                }

                if (!empty($this->password) || is_string($this->password)) {
                    $iv = Random::string(8);
                    $symkey = pack('H*', md5($this->password . $iv)); // symkey is short for symmetric key
                    $symkey.= substr(pack('H*', md5($symkey . $this->password . $iv)), 0, 8);
                    $des = new Crypt_TripleDES();
                    $des->setKey($symkey);
                    $des->setIV($iv);
                    $iv = strtoupper(bin2hex($iv));
                    $RSAPrivateKey = "-----BEGIN RSA PRIVATE KEY-----\r\n" .
                                     "Proc-Type: 4,ENCRYPTED\r\n" .
                                     "DEK-Info: DES-EDE3-CBC,$iv\r\n" .
                                     "\r\n" .
                                     chunk_split(base64_encode($des->encrypt($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 private
     * @see setPublicKeyFormat()
     * @param String $RSAPrivateKey
     * @return String
     */
    function _convertPublicKey($n, $e)
    {
        $signed = $this->publicKeyFormat != CRYPT_RSA_PUBLIC_FORMAT_XML;

        $modulus = $n->toBytes($signed);
        $publicExponent = $e->toBytes($signed);

        switch ($this->publicKeyFormat) {
            case CRYPT_RSA_PUBLIC_FORMAT_RAW:
                return array('e' => $e->copy(), 'n' => $n->copy());
            case CRYPT_RSA_PUBLIC_FORMAT_XML:
                return "<RSAKeyValue>\r\n" .
                       '  <Modulus>' . base64_encode($modulus) . "</Modulus>\r\n" .
                       '  <Exponent>' . base64_encode($publicExponent) . "</Exponent>\r\n" .
                       '</RSAKeyValue>';
                break;
            case CRYPT_RSA_PUBLIC_FORMAT_OPENSSH:
                // from <http://tools.ietf.org/html/rfc4253#page-15>:
                // string    "ssh-rsa"
                // mpint     e
                // mpint     n
                $RSAPublicKey = pack('Na*Na*Na*', strlen('ssh-rsa'), 'ssh-rsa', strlen($publicExponent), $publicExponent, strlen($modulus), $modulus);
                $RSAPublicKey = 'ssh-rsa ' . base64_encode($RSAPublicKey) . ' ' . $this->comment;

                return $RSAPublicKey;
            default: // eg. CRYPT_RSA_PUBLIC_FORMAT_PKCS1_RAW or CRYPT_RSA_PUBLIC_FORMAT_PKCS1
                // 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*', CRYPT_RSA_ASN1_INTEGER, $this->_encodeLength(strlen($modulus)), $modulus),
                    'publicExponent' => pack('Ca*a*', CRYPT_RSA_ASN1_INTEGER, $this->_encodeLength(strlen($publicExponent)), $publicExponent)
                );

                $RSAPublicKey = pack('Ca*a*a*',
                    CRYPT_RSA_ASN1_SEQUENCE, $this->_encodeLength(strlen($components['modulus']) + strlen($components['publicExponent'])),
                    $components['modulus'], $components['publicExponent']
                );

                if ($this->publicKeyFormat == CRYPT_RSA_PUBLIC_FORMAT_PKCS1_RAW) {
                    $RSAPublicKey = "-----BEGIN RSA PUBLIC KEY-----\r\n" .
                                    chunk_split(base64_encode($RSAPublicKey), 64) .
                                    '-----END RSA PUBLIC KEY-----';
                } else {
                    // sequence(oid(1.2.840.113549.1.1.1), null)) = rsaEncryption.
                    $rsaOID = pack('H*', '300d06092a864886f70d0101010500'); // hex version of MA0GCSqGSIb3DQEBAQUA
                    $RSAPublicKey = chr(0) . $RSAPublicKey;
                    $RSAPublicKey = chr(3) . $this->_encodeLength(strlen($RSAPublicKey)) . $RSAPublicKey;

                    $RSAPublicKey = pack('Ca*a*',
                        CRYPT_RSA_ASN1_SEQUENCE, $this->_encodeLength(strlen($rsaOID . $RSAPublicKey)), $rsaOID . $RSAPublicKey
                    );

                    $RSAPublicKey = "-----BEGIN PUBLIC KEY-----\r\n" .
                                     chunk_split(base64_encode($RSAPublicKey), 64) .
                                     '-----END PUBLIC KEY-----';
                }

                return $RSAPublicKey;
        }
    }

    /**
     * Break a public or private key down into its constituant components
     *
     * @access private
     * @see _convertPublicKey()
     * @see _convertPrivateKey()
     * @param String $key
     * @param Integer $type
     * @return Array
     */
    function _parseKey($key, $type)
    {
        if ($type != CRYPT_RSA_PUBLIC_FORMAT_RAW && !is_string($key)) {
            return false;
        }

        switch ($type) {
            case CRYPT_RSA_PUBLIC_FORMAT_RAW:
                if (!is_array($key)) {
                    return false;
                }
                $components = array();
                switch (true) {
                    case isset($key['e']):
                        $components['publicExponent'] = $key['e']->copy();
                        break;
                    case isset($key['exponent']):
                        $components['publicExponent'] = $key['exponent']->copy();
                        break;
                    case isset($key['publicExponent']):
                        $components['publicExponent'] = $key['publicExponent']->copy();
                        break;
                    case isset($key[0]):
                        $components['publicExponent'] = $key[0]->copy();
                }
                switch (true) {
                    case isset($key['n']):
                        $components['modulus'] = $key['n']->copy();
                        break;
                    case isset($key['modulo']):
                        $components['modulus'] = $key['modulo']->copy();
                        break;
                    case isset($key['modulus']):
                        $components['modulus'] = $key['modulus']->copy();
                        break;
                    case isset($key[1]):
                        $components['modulus'] = $key[1]->copy();
                }
                return isset($components['modulus']) && isset($components['publicExponent']) ? $components : false;
            case CRYPT_RSA_PRIVATE_FORMAT_PKCS1:
            case CRYPT_RSA_PRIVATE_FORMAT_PKCS8:
            case CRYPT_RSA_PUBLIC_FORMAT_PKCS1:
                /* Although PKCS#1 proposes a format that public and private keys can use, encrypting them is
                   "outside the scope" of PKCS#1.  PKCS#1 then refers you to PKCS#12 and PKCS#15 if you're wanting to
                   protect private keys, however, that's not what OpenSSL* does.  OpenSSL protects private keys by adding
                   two new "fields" to the key - DEK-Info and Proc-Type.  These fields are discussed here:

                   http://tools.ietf.org/html/rfc1421#section-4.6.1.1
                   http://tools.ietf.org/html/rfc1421#section-4.6.1.3

                   DES-EDE3-CBC as an algorithm, however, is not discussed anywhere, near as I can tell.
                   DES-CBC and DES-EDE are discussed in RFC1423, however, DES-EDE3-CBC isn't, nor is its key derivation
                   function.  As is, the definitive authority on this encoding scheme isn't the IETF but rather OpenSSL's
                   own implementation.  ie. the implementation *is* the standard and any bugs that may exist in that
                   implementation are part of the standard, as well.

                   * OpenSSL is the de facto standard.  It's utilized by OpenSSH and other projects */
                if (preg_match('#DEK-Info: (.+),(.+)#', $key, $matches)) {
                    $iv = pack('H*', trim($matches[2]));
                    $symkey = pack('H*', md5($this->password . substr($iv, 0, 8))); // symkey is short for symmetric key
                    $symkey.= pack('H*', md5($symkey . $this->password . substr($iv, 0, 8)));
                    // remove the Proc-Type / DEK-Info sections as they're no longer needed
                    $key = preg_replace('#^(?:Proc-Type|DEK-Info): .*#m', '', $key);
                    $ciphertext = $this->_extractBER($key);
                    if ($ciphertext === false) {
                        $ciphertext = $key;
                    }
                    switch ($matches[1]) {
                        case 'AES-256-CBC':
                            $crypto = new Crypt_AES();
                            break;
                        case 'AES-128-CBC':
                            $symkey = substr($symkey, 0, 16);
                            $crypto = new Crypt_AES();
                            break;
                        case 'DES-EDE3-CFB':
                            $crypto = new Crypt_TripleDES(CRYPT_DES_MODE_CFB);
                            break;
                        case 'DES-EDE3-CBC':
                            $symkey = substr($symkey, 0, 24);
                            $crypto = new Crypt_TripleDES();
                            break;
                        case 'DES-CBC':
                            $crypto = new Crypt_DES();
                            break;
                        default:
                            return false;
                    }
                    $crypto->setKey($symkey);
                    $crypto->setIV($iv);
                    $decoded = $crypto->decrypt($ciphertext);
                } else {
                    $decoded = $this->_extractBER($key);
                }

                if ($decoded !== false) {
                    $key = $decoded;
                }

                $components = array();

                if (ord($this->_string_shift($key)) != CRYPT_RSA_ASN1_SEQUENCE) {
                    return false;
                }
                if ($this->_decodeLength($key) != strlen($key)) {
                    return false;
                }

                $tag = ord($this->_string_shift($key));
                /* intended for keys for which OpenSSL's asn1parse returns the following:

                    0:d=0  hl=4 l= 631 cons: SEQUENCE
                    4:d=1  hl=2 l=   1 prim:  INTEGER           :00
                    7:d=1  hl=2 l=  13 cons:  SEQUENCE
                    9:d=2  hl=2 l=   9 prim:   OBJECT            :rsaEncryption
                   20:d=2  hl=2 l=   0 prim:   NULL
                   22:d=1  hl=4 l= 609 prim:  OCTET STRING

                   ie. PKCS8 keys*/

                if ($tag == CRYPT_RSA_ASN1_INTEGER && substr($key, 0, 3) == "\x01\x00\x30") {
                    $this->_string_shift($key, 3);
                    $tag = CRYPT_RSA_ASN1_SEQUENCE;
                }

                if ($tag == CRYPT_RSA_ASN1_SEQUENCE) {
                    $temp = $this->_string_shift($key, $this->_decodeLength($key));
                    if (ord($this->_string_shift($temp)) != CRYPT_RSA_ASN1_OBJECT) {
                        return false;
                    }
                    $length = $this->_decodeLength($temp);
                    switch ($this->_string_shift($temp, $length)) {
                        case "\x2a\x86\x48\x86\xf7\x0d\x01\x01\x01": // rsaEncryption
                            break;
                        case "\x2a\x86\x48\x86\xf7\x0d\x01\x05\x03": // pbeWithMD5AndDES-CBC
                            /*
                               PBEParameter ::= SEQUENCE {
                                   salt OCTET STRING (SIZE(8)),
                                   iterationCount INTEGER }
                            */
                            if (ord($this->_string_shift($temp)) != CRYPT_RSA_ASN1_SEQUENCE) {
                                return false;
                            }
                            if ($this->_decodeLength($temp) != strlen($temp)) {
                                return false;
                            }
                            $this->_string_shift($temp); // assume it's an octet string
                            $salt = $this->_string_shift($temp, $this->_decodeLength($temp));
                            if (ord($this->_string_shift($temp)) != CRYPT_RSA_ASN1_INTEGER) {
                                return false;
                            }
                            $this->_decodeLength($temp);
                            list(, $iterationCount) = unpack('N', str_pad($temp, 4, chr(0), STR_PAD_LEFT));
                            $this->_string_shift($key); // assume it's an octet string
                            $length = $this->_decodeLength($key);
                            if (strlen($key) != $length) {
                                return false;
                            }

                            $crypto = new Crypt_DES();
                            $crypto->setPassword($this->password, 'pbkdf1', 'md5', $salt, $iterationCount);
                            $key = $crypto->decrypt($key);
                            if ($key === false) {
                                return false;
                            }
                            return $this->_parseKey($key, CRYPT_RSA_PRIVATE_FORMAT_PKCS1);
                        default:
                            return false;
                    }
                    /* intended for keys for which OpenSSL's asn1parse returns the following:

                        0:d=0  hl=4 l= 290 cons: SEQUENCE
                        4:d=1  hl=2 l=  13 cons:  SEQUENCE
                        6:d=2  hl=2 l=   9 prim:   OBJECT            :rsaEncryption
                       17:d=2  hl=2 l=   0 prim:   NULL
                       19:d=1  hl=4 l= 271 prim:  BIT STRING */
                    $tag = ord($this->_string_shift($key)); // skip over the BIT STRING / OCTET STRING tag
                    $this->_decodeLength($key); // skip over the BIT STRING / OCTET STRING length
                    // "The initial octet shall encode, as an unsigned binary integer wtih bit 1 as the least significant bit, the number of
                    //  unused bits in the final subsequent octet. The number shall be in the range zero to seven."
                    //  -- http://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf (section 8.6.2.2)
                    if ($tag == CRYPT_RSA_ASN1_BITSTRING) {
                        $this->_string_shift($key);
                    }
                    if (ord($this->_string_shift($key)) != CRYPT_RSA_ASN1_SEQUENCE) {
                        return false;
                    }
                    if ($this->_decodeLength($key) != strlen($key)) {
                        return false;
                    }
                    $tag = ord($this->_string_shift($key));
                }
                if ($tag != CRYPT_RSA_ASN1_INTEGER) {
                    return false;
                }

                $length = $this->_decodeLength($key);
                $temp = $this->_string_shift($key, $length);
                if (strlen($temp) != 1 || ord($temp) > 2) {
                    $components['modulus'] = new BigInteger($temp, 256);
                    $this->_string_shift($key); // skip over CRYPT_RSA_ASN1_INTEGER
                    $length = $this->_decodeLength($key);
                    $components[$type == CRYPT_RSA_PUBLIC_FORMAT_PKCS1 ? 'publicExponent' : 'privateExponent'] = new BigInteger($this->_string_shift($key, $length), 256);

                    return $components;
                }
                if (ord($this->_string_shift($key)) != CRYPT_RSA_ASN1_INTEGER) {
                    return false;
                }
                $length = $this->_decodeLength($key);
                $components['modulus'] = new BigInteger($this->_string_shift($key, $length), 256);
                $this->_string_shift($key);
                $length = $this->_decodeLength($key);
                $components['publicExponent'] = new BigInteger($this->_string_shift($key, $length), 256);
                $this->_string_shift($key);
                $length = $this->_decodeLength($key);
                $components['privateExponent'] = new BigInteger($this->_string_shift($key, $length), 256);
                $this->_string_shift($key);
                $length = $this->_decodeLength($key);
                $components['primes'] = array(1 => new BigInteger($this->_string_shift($key, $length), 256));
                $this->_string_shift($key);
                $length = $this->_decodeLength($key);
                $components['primes'][] = new BigInteger($this->_string_shift($key, $length), 256);
                $this->_string_shift($key);
                $length = $this->_decodeLength($key);
                $components['exponents'] = array(1 => new BigInteger($this->_string_shift($key, $length), 256));
                $this->_string_shift($key);
                $length = $this->_decodeLength($key);
                $components['exponents'][] = new BigInteger($this->_string_shift($key, $length), 256);
                $this->_string_shift($key);
                $length = $this->_decodeLength($key);
                $components['coefficients'] = array(2 => new BigInteger($this->_string_shift($key, $length), 256));

                if (!empty($key)) {
                    if (ord($this->_string_shift($key)) != CRYPT_RSA_ASN1_SEQUENCE) {
                        return false;
                    }
                    $this->_decodeLength($key);
                    while (!empty($key)) {
                        if (ord($this->_string_shift($key)) != CRYPT_RSA_ASN1_SEQUENCE) {
                            return false;
                        }
                        $this->_decodeLength($key);
                        $key = substr($key, 1);
                        $length = $this->_decodeLength($key);
                        $components['primes'][] = new BigInteger($this->_string_shift($key, $length), 256);
                        $this->_string_shift($key);
                        $length = $this->_decodeLength($key);
                        $components['exponents'][] = new BigInteger($this->_string_shift($key, $length), 256);
                        $this->_string_shift($key);
                        $length = $this->_decodeLength($key);
                        $components['coefficients'][] = new BigInteger($this->_string_shift($key, $length), 256);
                    }
                }

                return $components;
            case CRYPT_RSA_PUBLIC_FORMAT_OPENSSH:
                $parts = explode(' ', $key, 3);

                $key = isset($parts[1]…

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