/tanora.org/www/framework/library/encryption.php

<?php

/**
 * This class is intended to provide robust solutions for encrypting
 * and decrypting data.
 */

class Encryption {
		
	/**
	 * Encrypts data with the given data, key, cipher, and mode.
	 */
	public static function encrypt($data, $key = NULL, $cipher = NULL, $mode = NULL) {
		
		if(is_null($key)) {
			$key = Framework::config('encryption', 'key');
		}
		if(is_null($cipher)) {
			$cipher = Framework::config('encryption', 'cipher');
		}
		if(is_null($mode)) {
			$mode = Framework::config('encryption', 'mode');
		}
		
		if(extension_loaded('mcrypt') !== FALSE) {
			$iv = self::_create_iv($cipher, $mode);
			$data = self::_pad($data, $cipher, $mode);
			return base64_encode(mcrypt_encrypt($cipher, $key, $data, $mode, $iv));
		} else {
			Framework::warn('Mcrypt extension is not loaded. Be warned: your data is not encrypted.');
			return $data;
		}
		
	}
	
	/**
	 * Decrypts a string with the given string, key, cipher, and mode.
	 */
	public static function decrypt($string, $key = NULL, $cipher = NULL, $mode = NULL) {
		
		if(is_null($key)) {
			$key = Framework::config('encryption', 'key');
		}
		if(is_null($cipher)) {
			$cipher = Framework::config('encryption', 'cipher');
		}
		if(is_null($mode)) {
			$mode = Framework::config('encryption', 'mode');
		}
		
		if(extension_loaded('mcrypt') !== FALSE) {
			$iv = self::_get_iv($cipher, $mode, $string);
			$data = mcrypt_decrypt($cipher, $key, base64_decode($string), $mode, $iv);
			return self::_unpad($data, $cipher, $mode); 
		} else {
			Framework::warn('Mcrypt extension is not loaded. Be warned: your data is not encrypted.');
			return $string;
		}
		
	}
	
	/**
	 * Returns a blowfish encrypted string.
	 * @param string a string to encrpyt
	 * @param cost base-2 logarithm of the iteration count
	 * @param entropy 22 random alphanumeric characters
	 */
	static public function blowfish($string, $cost = 10, $entropy = NULL) {
		$salt = '$2a$';
		// Security fix from 5.3.7 and up
		if(PHP_VERSION_ID >= 50307) {
			$salt = '$2y$';
		}
		// Base-2 logarithm of the iteration count.
		$salt .= $cost . '$';
		// 22 random digits "./0-9A-Za-z"
		if(is_null($entropy)) {
			$salt .= self::_keygen(22);
		} else {
			$salt .= $entropy;
		}
		return crypt($string, $salt);
	}
	
	/**
	 * Compares a string encrypted with crypt() against an un-encrypted
	 * string. Parameters can be in either order.
	 * @param source an encrypted string
	 * @param target an unencrypted string to compare
	 */
	static public function crypt_compare($source, $target) {
		$attempt = crypt($target, $source) == $source;
		if($attempt === TRUE) {
			return TRUE;
		}
		$attempt = crypt($source, $target) == $target;
		if($attempt === TRUE) {
			return TRUE;
		}
		return FALSE;
	}
	
	/**
	 * Creates additional padding.
	 */
	private static function _pad($data, $cipher, $mode) {
		$block_size = self::_get_block_size($cipher, $mode);
		$pad_size = $block_size - (strlen($data) % $block_size);
		return $data . str_repeat(chr($pad_size), $pad_size);
	}
	
	/**
	 * Removes additional padding.
	 */
	private static function _unpad($data, $cipher, $mode) {
		$length = strlen($data);
		$pad_size = ord($data[$length - 1]);
		return substr($data, 0, -$pad_size);
	}
	
	/**
	 * Gets the block size for the given cipher and mode.
	 */
	private static function _get_block_size($cipher, $mode) {
		return mcrypt_get_block_size($cipher, $mode);
	}
	
	/**
	 * Generates an initialization vector for the given cipher and
	 * mode.
	 */
	private static function _create_iv($cipher, $mode) {
		$iv_size = mcrypt_get_iv_size($cipher, $mode);
		return mcrypt_create_iv($iv_size, MCRYPT_RAND);
	}
	
	/**
	 * Gets an initialization vector from an encrypted string.
	 */
	private static function _get_iv($cipher, $mode, $string) {
		$iv_size = mcrypt_get_iv_size($cipher, $mode);
		return substr($string, 0, $iv_size);		
	}
	
	/**
	 * Returns a unique string of random alphanumeric characters.
	 * @param length the length of the key
	 */
	private static function _keygen($length = 32) {
		$seed = '';
		$hash = '';
		// Make the hash long enough.
		while(strlen($hash) < $length) {
			// Require the seed to be at least equal to the length in order to get a more unique hash.
			while(strlen($seed) < $length) {
				$seed .= uniqid((string) microtime().rand(), true);
			}
			$hash .= hash('sha256', $seed);
		}
		return substr($hash,0,$length);
	}
	
}

?>