<?php
/**
 * A helper class for cryptographical things like hashing passwords and so on
 *
 * @author		Roland Haeder <webmaster@ship-simu.org>
 * @version		0.0.0
 * @copyright	Copyright (c) 2007 - 2009 Roland Haeder, this is free software
 * @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 CryptoHelper extends BaseFrameworkSystem implements Cryptable {
	// Exception constants
	const EXCEPTION_ENCRYPT_MISSING = 0x1f0;
	const EXCEPTION_ENCRYPT_INVALID = 0x1f1;

	/**
	 * An instance of this own clas
	 */
	private static $selfInstance = null;

	/**
	 * Instance of the random number generator
	 */
	private $rngInstance = null;

	/**
	 * Salt for hashing operations
	 */
	private $salt = '';

	/**
	 * Seperator on many places
	 */
	private $seperator = '|';

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

		// Clean up a little
		$this->removeNumberFormaters();
		$this->removeSystemArray();
	}

	/**
	 * Creates an instance of this class
	 *
	 * @return	$cryptoInstance		An instance of this crypto helper class
	 */
	public final static function createCryptoHelper () {
		// Get a new instance
		$cryptoInstance = new CryptoHelper();

		// Initialize the hasher
		$cryptoInstance->initHasher();

		// Return the instance
		return $cryptoInstance;
	}

	/**
	 * Get a singleton instance of this class
	 *
	 * @return	$selfInstance	An instance of this crypto helper class
	 */
	public final static function getInstance () {
		// Is no instance there?
		if (is_null(self::$selfInstance)) {
			// Then get a new one
			self::$selfInstance = self::createCryptoHelper();
		}

		// Return the instance
		return self::$selfInstance;
	}

	/**
	 * Initializes the hasher for different purposes.
	 *
	 * @return	void
	 */
	protected function initHasher () {
		// Initialize the random number generator which is required by some crypto methods
		$this->rngInstance = ObjectFactory::createObjectByConfiguredName('rng_class');

		// Generate a salt for the hasher
		$this->generateSalt();
	}

	/**
	 * Generates the salt based on configured length
	 *
	 * @return	void
	 */
	private function generateSalt () {
		// Get a random string from the RNG
		$randomString = $this->rngInstance->randomString();

		// Get config entry for salt length
		$length = $this->getConfigInstance()->readConfig('salt_length');

		// Keep only defined number of characters
		$this->salt = substr(sha1($randomString), -$length, $length);
	}

	/**
	 * Hashes a string with salt and returns the hash. If an old previous hash
	 * is supplied the method will use the first X chars of that hash for hashing
	 * the password. This is useful if you want to check if password is identical
	 * for authorization purposes.
	 *
	 * @param	$str		Unhashed string
	 * @param	$oldHash	A hash from previous hashed string
	 * @return	$hashed		The hashed and salted string
	 */
	public function hashString ($str, $oldHash = '') {
		// Cast the string
		$str = (string) $str;

		// Default is the default salt ;-)
		$salt = $this->salt;

		// Is the old password set?
		if (!empty($oldHash)) {
			// Use the salt from hash, first get length
			$length = $this->getConfigInstance()->readConfig('salt_length');

			// Then extract the X first characters from the hash as our salt
			$salt = substr($oldHash, 0, $length);
		} // END - if

		// Hash the password with salt
		//* DEBUG: */ echo "salt=".$salt."/plain=".$str."<br />\n";
		$hashed = $salt . md5(sprintf($this->getConfigInstance()->readConfig('hash_mask'),
			$salt,
			$this->rngInstance->getFixedSalt(),
			$str
		));

		// And return it
		return $hashed;
	}

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

		// Get key
		if ($this->getConfigInstance()->readConfig('crypt_fixed_salt') == 'Y') {
			$key = md5($this->rngInstance->getFixedSalt());
		} else {
			$key = md5($this->rngInstance->getExtraSalt());
		}

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

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

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

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

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

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

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

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

			case 8:
				$garbageString = sha1($this->rngInstance->randomString(10)) . $this->seperator . base64_encode($str) . $this->seperator . sha1($this->rngInstance->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	$str		The unencrypted string
	 */
	public function decryptString ($encrypted) {
		// Init crypto module
		$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
		$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);

		// Get key
		if ($this->getConfigInstance()->readConfig('crypt_fixed_salt') == 'Y') {
			$key = md5($this->rngInstance->getFixedSalt());
		} else {
			$key = md5($this->rngInstance->getExtraSalt());
		}

		// 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]
?>