PHP 简单的加密解密算法

<?php
/**
 * 
 * @创建时间：2015-3-12 下午2:07:33
 * @作者：YuMing
 * @描述：异或加密解密类
 */
class Yihuo extends CI_Controller {

	//加密秘钥
	public $key0 = '123456';
	
	function __construct() {
		parent::__construct ();
		header ( "Content-type:text/html;charset=utf-8" );
	}
	
	public function  index(){
		$this->load->view('templates/header');
		$this->load->view('yihuo');
		$this->load->view('templates/footer');
	}
	
	/**
	 * 
	 * @创建时间：2015-3-12 下午2:06:47
	 * @作者：YuMing
	 * @描述：异或加密
	 * @param string $str
	 * @return string
	 */	
	public function encode($str = '') {
		
		$data = $this->input->post();
		if(!empty($data['msg'])){
			$str =$data['msg'];		
		}
		$keyBytes = $this->getBytes ( $this->key0 );
		$bytes = $this->getBytes ( $str );
		for($i = 0; $i < count ( $bytes ); $i ++) {
			foreach ( $keyBytes as $keyBytes0 ) {
				$bytes [$i] = $bytes [$i] ^ $keyBytes0;
			}
		}
		
		$encode_str= $this->toStr ( $bytes );
		
		echo $encode_str;
		return $encode_str;
	}
	/**
	 * 
	 * @创建时间：2015-3-12 下午2:06:35
	 * @作者：YuMing
	 * @描述：异或解密
	 * @param unknown $str
	 * @return string
	 */
	public function decode($str ='') {
		$data = $this->input->post();
		if(!empty($data['msg'])){
			$str =$data['msg'];
		}
		
		$keyBytes = $this->getBytes ( $this->key0 );		
		$bytes = $this->getBytes ( $str );
		for($i = 0; $i < count ( $bytes ); $i ++) {
			foreach ( $keyBytes as $keyBytes0 ) {
				$bytes[$i] = $bytes [$i] ^ $keyBytes0;
			}
		}
		$decode_str= $this->toStr ( $bytes );
		echo $decode_str;
		return $decode_str;
	}
	/**
	 * 
	 * @创建时间：2015-3-12 下午2:05:59
	 * @作者：YuMing
	 * @描述：将Bytes数组转换为String
	 * @param unknown $bytes
	 * @return string
	 */
	public static function toStr($bytes) {
		$str = '';
		foreach ( $bytes as $ch ) {
			$str .= chr ( $ch );
		}
		return $str;
	}
	/**
	 * 
	 * @创建时间：2015-3-12 下午2:06:18
	 * @作者：YuMing
	 * @描述：将String转换为Bytes数组
	 * @param unknown $string
	 * @return multitype:number
	 */
	public static function getBytes($string) {
		$bytes = array ();
		for($i = 0; $i < strlen ( $string ); $i ++) {
			$bytes [] = ord ( $string [$i] );
		}
		return $bytes;
	}
}