加密，解密方法

加密，解密方法

//加密函数
    function jiami($txt, $key = 'secure_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 $ch . $tmp;
    }

    //解密函数
    function jiemi($txt, $key = 'secure_key')
    {
        $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-=_";
        $ch = $txt [0];
        $nh = strpos($chars, $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 base64_decode($tmp);
    }