early idea for easy crypther

Crypter.php

<?php
class Crypter {
	public static $cipher = MCRYPT_TWOFISH;
	public $key;
	public $authKey;
	
	public function __construct($key, $authKey) {
		$this->key = base64_decode($key);
		$this->authKey = base64_decode($authKey);
	}
	
	
	public function encrypt($string) {
		$ivSize = mcrypt_get_iv_size(static::$cipher, "cbc");
		$iv = mcrypt_create_iv($ivSize, MCRYPT_DEV_URANDOM);
		$encrypt = mcrypt_encrypt(static::$cipher, $this->key, $string, "cbc", $iv);
		$cipher = $encrypt.$iv;
		$mac = hash_hmac("sha256", $cipher, $this->authKey, true);
		return base64_encode($cipher.$mac);
	}
	
	public function decrypt($string) {
		$ivSize = mcrypt_get_iv_size(static::$cipher, "cbc");
		$term = base64_decode($string);
		$mac = substr($term, -32);
		$cipher = substr($term, 0, -32);
		if(hash_hmac("sha256", $cipher, $this->authKey, true) !== $mac) {
				throw new Exception("Cannot decrypt message, message is corrupted");
		}
		
		$iv = substr($cipher, $ivSize * -1);
		$crypt = substr($cipher, 0, $ivSize * -1);
		
		return mcrypt_decrypt(static::$cipher, $this->key, $crypt, "cbc", $iv);
	}
	
	public static function generateKey() {
		$ivSize = mcrypt_get_iv_size(static::$cipher, "cbc");
		return base64_encode(mcrypt_create_iv($ivSize, MCRYPT_DEV_URANDOM));
	}
}