<?php
/**
 * A mcrypt-based encryption stream
 *
 * @author		Roland Haeder <webmaster@ship-simu.org>
 * @version		0.0.0
 * @copyright	Copyright (c) 2007, 2008 Roland Haeder, 2009, 2010 Core Developer Team
 * @license		GNU GPL 3.0 or any newer version
 * @link		http://www.ship-simu.org
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
class McryptStream extends BaseStream implements EncryptableStream {
	/**
	 * Seperator on many places
	 */
	private $seperator = '|';

	/**
	 * Protected constructor
	 *
	 * @return	void
	 */
	protected function __construct () {
		// Call parent constructor
		parent::__construct(__CLASS__);
	}

	/**
	 * Creates an instance of this node class
	 *
	 * @param	$rngInstance		An RNG instance
	 * @return	$streamInstance		An instance of this node class
	 */
	public final static function createMcryptStream (RandomNumberGenerator $rngInstance) {
		// Get a new instance
		$streamInstance = new McryptStream();

		// Set the RNG instance
		$streamInstance->setRngInstance($rngInstance);

		// Return the instance
		return $streamInstance;
	}

	/**
	 * Encrypt the string with fixed salt
	 *
	 * @param	$str		The unencrypted string
	 * @return	$encrypted	Encrypted string
	 */
	public function encryptStream ($str) {
		// Init crypto module
		$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
		$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);

		// Generate key
		$key = $this->getRngInstance()->generateKey();

		// Add some "garbage" to the string
		switch ($this->getRngInstance()->randomNumber(0, 8)) {
			case 0:
				$garbageString = crc32($this->getRngInstance()->randomString(10)) . $this->seperator . base64_encode($str) . $this->seperator . crc32($this->getRngInstance()->randomString(20));
				break;

			case 1:
				$garbageString = crc32($this->getRngInstance()->randomString(10)) . $this->seperator . base64_encode($str) . $this->seperator . md5($this->getRngInstance()->randomString(20));
				break;

			case 2:
				$garbageString = crc32($this->getRngInstance()->randomString(10)) . $this->seperator . base64_encode($str) . $this->seperator . sha1($this->getRngInstance()->randomString(20));
				break;

			case 3:
				$garbageString = md5($this->getRngInstance()->randomString(10)) . $this->seperator . base64_encode($str) . $this->seperator . crc32($this->getRngInstance()->randomString(20));
				break;

			case 4:
				$garbageString = md5($this->getRngInstance()->randomString(10)) . $this->seperator . base64_encode($str) . $this->seperator . md5($this->getRngInstance()->randomString(20));
				break;

			case 5:
				$garbageString = md5($this->getRngInstance()->randomString(10)) . $this->seperator . base64_encode($str) . $this->seperator . sha1($this->getRngInstance()->randomString(20));
				break;

			case 6:
				$garbageString = sha1($this->getRngInstance()->randomString(10)) . $this->seperator . base64_encode($str) . $this->seperator . crc32($this->getRngInstance()->randomString(20));
				break;

			case 7:
				$garbageString = sha1($this->getRngInstance()->randomString(10)) . $this->seperator . base64_encode($str) . $this->seperator . md5($this->getRngInstance()->randomString(20));
				break;

			case 8:
				$garbageString = sha1($this->getRngInstance()->randomString(10)) . $this->seperator . base64_encode($str) . $this->seperator . sha1($this->getRngInstance()->randomString(20));
				break;
		}

		// Encrypt the string
		$encrypted = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $garbageString, MCRYPT_MODE_ECB, $iv);

		// Return the string
		return $encrypted;
	}

	/**
	 * Decrypt the string with fixed salt
	 *
	 * @param	$encrypted	Encrypted string
	 * @return	$str		The unencrypted string
	 */
	public function decryptStream ($encrypted) {
		// Init crypto module
		$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
		$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);

		// Generate key
		$key = $this->getRngInstance()->generateKey();

		// Decrypt the string
		$garbageString = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $encrypted, MCRYPT_MODE_ECB, $iv);

		// Get the real string out
		$strArray = explode($this->seperator, $garbageString);

		// Does the element count match?
		assert(count($strArray) == 3);

		// Decode the string
		$str = base64_decode($strArray[1]);

		// Trim trailing nulls away
		$str = rtrim($str, "\0");

		// Return the string
		return $str;
	}
}

// [EOF]
?>