[PHP]加密解密代码

<?php$Cache = new ESApi();$json = $Cache->encoded_url($_REQUEST['txt'],$_REQUEST['key']);echo json_encode($json,JSON_PRETTY_PRINT|JSON_UNESCAPED_UNICODE); class ESApi{    //编码    public function encoded_url($txt, $key = ''){        $txt = $txt . $key;        $chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-=+";        $nh = rand(0, 64);        $ch = $chars[$nh];        $mdKey = md5($key . $ch);        $mdKey = substr($mdKey, $nh % 8, $nh % 8 + 7);        $txt = base64_encode($txt);        $tmp = '';        $i = 0;        $j = 0;        $k = 0;        for ($i = 0; $i < strlen($txt); $i++) {            $k = $k == strlen($mdKey) ? 0 : $k;            $j = ($nh + strpos($chars, $txt[$i]) + ord($mdKey[$k++])) % 64;            $tmp .= $chars[$j];        }        return urlencode(base64_encode($ch . $tmp));    }    //解码    public function decode_url($txt, $key = ''){        $txt = base64_decode(urldecode($txt));        $chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-=+";        $ch = $txt[0]; if(!empty($txt)){ $nh = strpos($chars, $ch); }else{ $nh = $ch; }        $mdKey = md5($key . $ch);        $mdKey = substr($mdKey, $nh % 8, $nh % 8 + 7);        $txt = substr($txt, 1);        $tmp = '';        $i = 0;        $j = 0;        $k = 0;        for ($i = 0; $i < strlen($txt); $i++) {            $k = $k == strlen($mdKey) ? 0 : $k;            $j = strpos($chars, $txt[$i]) - $nh - ord($mdKey[$k++]);            while ($j < 0) {                $j += 64;            }            $tmp .= $chars[$j];        }        return trim(base64_decode($tmp), $key);    }}