OpenPGP_S2K::make_key PHP Method

    function make_key($pass, $size)
    {
        switch ($this->type) {
            case 0:
                return $this->sized_hash($pass, $size);
            case 1:
                return $this->sized_hash($this->salt . $pass, $size);
            case 3:
                return $this->sized_hash($this->iterate($this->salt . $pass), $size);
        }
    }

 public static function encrypt($passphrases_and_keys, $message, $symmetric_algorithm = 9)
 {
     list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($symmetric_algorithm);
     if (!$cipher) {
         throw new Exception("Unsupported cipher");
     }
     $prefix = crypt_random_string($key_block_bytes);
     $prefix .= substr($prefix, -2);
     $key = crypt_random_string($key_bytes);
     $cipher->setKey($key);
     $to_encrypt = $prefix . $message->to_bytes();
     $mdc = new OpenPGP_ModificationDetectionCodePacket(hash('sha1', $to_encrypt . "Ó", true));
     $to_encrypt .= $mdc->to_bytes();
     $encrypted = array(new OpenPGP_IntegrityProtectedDataPacket($cipher->encrypt($to_encrypt)));
     if (!is_array($passphrases_and_keys) && !$passphrases_and_keys instanceof IteratorAggregate) {
         $passphrases_and_keys = (array) $passphrases_and_keys;
     }
     foreach ($passphrases_and_keys as $pass) {
         if ($pass instanceof OpenPGP_PublicKeyPacket) {
             if (!in_array($pass->algorithm, array(1, 2, 3))) {
                 throw new Exception("Only RSA keys are supported.");
             }
             $crypt_rsa = new OpenPGP_Crypt_RSA($pass);
             $rsa = $crypt_rsa->public_key();
             $rsa->setEncryptionMode(CRYPT_RSA_ENCRYPTION_PKCS1);
             $esk = $rsa->encrypt(chr($symmetric_algorithm) . $key . pack('n', self::checksum($key)));
             $esk = pack('n', OpenPGP::bitlength($esk)) . $esk;
             array_unshift($encrypted, new OpenPGP_AsymmetricSessionKeyPacket($pass->algorithm, $pass->fingerprint(), $esk));
         } else {
             if (is_string($pass)) {
                 $s2k = new OpenPGP_S2K(crypt_random_string(10));
                 $cipher->setKey($s2k->make_key($pass, $key_bytes));
                 $esk = $cipher->encrypt(chr($symmetric_algorithm) . $key);
                 array_unshift($encrypted, new OpenPGP_SymmetricSessionKeyPacket($s2k, $esk, $symmetric_algorithm));
             }
         }
     }
     return new OpenPGP_Message($encrypted);
 }