<?php

/*
* xtea加密算法
*/

class XxTea {

  
/**
    * 加密方法
    *
    * @param string $str    需要加密的内容
    * @param string $key    密钥
    * @param bool $toBase64  是否base64(最好true吧，比如cookie加密长度有限制的)
    * return string
    */

  
public function encrypt($str, $key, $toBase64=
true) {

    
if ($str == “”) {

      
return “”;

    }

    $v = $
this->_str2long ( $str,
true );

    $k = $
this->_str2long ( $key,
false );

    
if (count ( $k ) < 4) {

      
for($i = count ( $k ); $i < 4; $i ++) {

        $k [$i] = 0;

      }

    }

    $n = count ( $v ) – 1;

    $z = $v [$n];

    $y = $v [0];

    $delta = 0x9E3779B9;

    $q = floor ( 6 + 52 / ($n + 1) );

    $sum = 0;

    
while ( 0 < $q — ) {

      $sum = $
this->_int32 ( $sum + $delta );

      $e = $sum >> 2 & 3;

      
for($p = 0; $p < $n; $p ++) {

        $y = $v [$p + 1];

        $mx = $
this->_int32 ( (($z >> 5 & 0x07ffffff) ^ $y << 2) + (($y >> 3 & 0x1fffffff) ^ $z << 4) ) ^ $
this->_int32 ( ($sum ^ $y) + ($k [$p & 3 ^ $e] ^ $z) );

        $z = $v [$p] = $
this->_int32 ( $v [$p] + $mx );

      }

      $y = $v [0];

      $mx = $
this->_int32 ( (($z >> 5 & 0x07ffffff) ^ $y << 2) + (($y >> 3 & 0x1fffffff) ^ $z << 4) ) ^ $
this->_int32 ( ($sum ^ $y) + ($k [$p & 3 ^ $e] ^ $z) );

      $z = $v [$n] = $
this->_int32 ( $v [$n] + $mx );

    }

    
if ($toBase64) {

      
return base64_encode($
this->_long2str ( $v,
false ));

    }

    
return $
this->_long2str ( $v,
false );

  }

  
/**
    * 解密方法
    *
    * @param string $str    加密后的内容
    * @param string $key    密钥
    * @param bool $toBase64  
    * return string
    */

  
public function decrypt($str, $key, $toBase64=
true) {

    
if ($str == “”) {

      
return “”;

    }

    $toBase64 && $str = base64_decode($str);

    $v = $
this->_str2long ( $str,
false );

    $k = $
this->_str2long ( $key,
false );

    
if (count ( $k ) < 4) {

      
for($i = count ( $k ); $i < 4; $i ++) {

        $k [$i] = 0;

      }

    }

    $n = count ( $v ) – 1;

    $z = $v [$n];

    $y = $v [0];

    $delta = 0x9E3779B9;

    $q = floor ( 6 + 52 / ($n + 1) );

    $sum = $
this->_int32 ( $q * $delta );

    
while ( $sum != 0 ) {

      $e = $sum >> 2 & 3;

      
for($p = $n; $p > 0; $p –) {

        $z = $v [$p – 1];

        $mx = $
this->_int32 ( (($z >> 5 & 0x07ffffff) ^ $y << 2) + (($y >> 3 & 0x1fffffff) ^ $z << 4) ) ^ $
this->_int32 ( ($sum ^ $y) + ($k [$p & 3 ^ $e] ^ $z) );

        $y = $v [$p] = $
this->_int32 ( $v [$p] – $mx );

      }

      $z = $v [$n];

      $mx = $
this->_int32 ( (($z >> 5 & 0x07ffffff) ^ $y << 2) + (($y >> 3 & 0x1fffffff) ^ $z << 4) ) ^ $
this->_int32 ( ($sum ^ $y) + ($k [$p & 3 ^ $e] ^ $z) );

      $y = $v [0] = $
this->_int32 ( $v [0] – $mx );

      $sum = $
this->_int32 ( $sum – $delta );

    }

    
return $
this->_long2str ( $v,
true );

  }

  
/**
    * 长整型转为字符串
    *
    * @param long $v
    * @param boolean $w
    * @return string
    */

  
private function _long2str($v, $w) {

    $len = count ( $v );

    $n = ($len – 1) << 2;

    
if ($w) {

      $m = $v [$len – 1];

      
if (($m < $n – 3) || ($m > $n))

        
return
false;

      $n = $m;

    }

    $s = array ();

    
for($i = 0; $i < $len; $i ++) {

      $s [$i] = pack (
“V”, $v [$i] );

    }

    
if ($w) {

      
return substr ( join ( ”, $s ), 0, $n );

    }
else {

      
return join ( ”, $s );

    }

  }

  
/**
    * 字符串转为长整型
    *
    * @param string $s
    * @param boolean $w
    * @return Ambigous <multitype:, number>
    */

  
private function _str2long($s, $w) {

    $v = unpack (
“V*”, $s . str_repeat (
“\0”, (4 – strlen ( $s ) % 4) & 3 ) );

    $v = array_values ( $v );

    
if ($w) {

      $v [count ( $v )] = strlen ( $s );

    }

    
return $v;

  }

  
private function _int32($n) {

    
while ( $n >= 2147483648 )

      $n -= 4294967296;

    
while ( $n <= – 2147483649 )

      $n += 4294967296;

    
return (
int ) $n;

  }

}

// 使用方式

$xxtea =
new XxTea();

$
string = ‘hello leven’;

$key = ‘123456’;

$encode = $xxtea->encrypt($
string,$key,
true);

$decode = $xxtea->decrypt($encode,$key,
true);

echo $encode;

echo
“<br />”;

echo $decode;