php 简单加密解密

<?php
namespace AppService;

/*
* @link http://kodcloud.com/
* @author warlee | e-mail:kodcloud@qq.com
* @copyright warlee 2014.(Shanghai)Co.,Ltd
* @license http://kodcloud.com/tools/licenses/license.txt
*------
* 字符串加解密类；
* 一次一密；且定时解密有效
* 可用于加密&动态key生成
* demo：
* 加密：echo Mcrypt::encode('abc','123');
* 解密：echo Mcrypt::decode('9f843I0crjv5y0dWE_-uwzL_mZRyRb1ynjGK4I_IACQ','123');
*/

class Mcrypt{
    private static $default_key = 'a!takA:d1989lmc1988ldEv,e';

    /**
     * 字符加密，一次一密,可定时解密有效
     *
     * @param string $string 原文
     * @param string $key 密钥
     * @param int $expiry 密文有效期,单位s,0 为永久有效
     * @return string 加密后的内容
     */
    public static function encode($string,$key = '', $expiry = 0){
        $ckeyLength = 4;
        $key = md5($key ? $key : self::$default_key); //解密密匙
        $keya = md5(substr($key, 0, 16));         //做数据完整性验证
        $keyb = md5(substr($key, 16, 16));         //用于变化生成的密文 (初始化向量IV)
        $keyc = substr(md5(microtime()), - $ckeyLength);
        $cryptkey = $keya . md5($keya . $keyc);
        $keyLength = strlen($cryptkey);
        $string = sprintf('%010d', $expiry ? $expiry + time() : 0).substr(md5($string . $keyb), 0, 16) . $string;
        $stringLength = strlen($string);

        $rndkey = array();
        for($i = 0; $i <= 255; $i++) {
            $rndkey[$i] = ord($cryptkey[$i % $keyLength]);
        }

        $box = range(0, 255);
        // 打乱密匙簿，增加随机性
        for($j = $i = 0; $i < 256; $i++) {
            $j = ($j + $box[$i] + $rndkey[$i]) % 256;
            $tmp = $box[$i];
            $box[$i] = $box[$j];
            $box[$j] = $tmp;
        }
        // 加解密，从密匙簿得出密匙进行异或，再转成字符
        $result = '';
        for($a = $j = $i = 0; $i < $stringLength; $i++) {
            $a = ($a + 1) % 256;
            $j = ($j + $box[$a]) % 256;
            $tmp = $box[$a];
            $box[$a] = $box[$j];
            $box[$j] = $tmp;
            $result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));
        }
        $result = $keyc . str_replace('=', '', base64_encode($result));
        $result = str_replace(array('+', '/', '='),array('-', '_', '.'), $result);
        return $result;
    }

    /**
     * 字符解密，一次一密,可定时解密有效
     *
     * @param string $string 密文
     * @param string $key 解密密钥
     * @return string 解密后的内容
     */
    public static function decode($string,$key = '')
    {
        $string = str_replace(array('-', '_', '.'),array('+', '/', '='), $string);
        $ckeyLength = 4;
        $key = md5($key ? $key : self::$default_key); //解密密匙
        $keya = md5(substr($key, 0, 16));         //做数据完整性验证
        $keyb = md5(substr($key, 16, 16));         //用于变化生成的密文 (初始化向量IV)
        $keyc = substr($string, 0, $ckeyLength);
        $cryptkey = $keya . md5($keya . $keyc);
        $keyLength = strlen($cryptkey);
        $string = base64_decode(substr($string, $ckeyLength));
        $stringLength = strlen($string);

        $rndkey = array();
        for($i = 0; $i <= 255; $i++) {
            $rndkey[$i] = ord($cryptkey[$i % $keyLength]);
        }

        $box = range(0, 255);
        // 打乱密匙簿，增加随机性
        for($j = $i = 0; $i < 256; $i++) {
            $j = ($j + $box[$i] + $rndkey[$i]) % 256;
            $tmp = $box[$i];
            $box[$i] = $box[$j];
            $box[$j] = $tmp;
        }
        // 加解密，从密匙簿得出密匙进行异或，再转成字符
        $result = '';
        for($a = $j = $i = 0; $i < $stringLength; $i++) {
            $a = ($a + 1) % 256;
            $j = ($j + $box[$a]) % 256;
            $tmp = $box[$a];
            $box[$a] = $box[$j];
            $box[$j] = $tmp;
            $result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));
        }
        if ((substr($result, 0, 10) == 0 || substr($result, 0, 10) - time() > 0)
            && substr($result, 10, 16) == substr(md5(substr($result, 26) . $keyb), 0, 16)
        ) {
            return substr($result, 26);
        } else {
            return '';
        }
    }
}