<"V", $v[$i]);
    return $w "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) $n;
  }
  public function encrypt($str, $key) {
    if ($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);
    }
    return $this->long2str($v, false);
  }
  public function decrypt($str, $key) {
    if ($str == '')
      return '';
    $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);
  }
}
//用法测试：
$strDemo = "www.jb51.net";
$key = "123456";
$pwd = new Xxtea();
$pwdrel = $pwd->encrypt($strDemo, $key);
echo $pwdrel;
echo "<br/>";
echo $pwd->decrypt($pwdrel, $key);
"color: #800000">PS：关于加密解密感兴趣的朋友还可以参考本站在线工具：

在线RSA加密/解密工具：

http://tools.jb51.net/password/rsa_encode
文字在线加密解密工具（包含AES、DES、RC4等）：

http://tools.jb51.net/password/txt_encode
在线散列/哈希算法加密工具:

http://tools.jb51.net/password/hash_encrypt
在线MD5/hash/SHA-1/SHA-2/SHA-256/SHA-512/SHA-3/RIPEMD-160加密工具：

http://tools.jb51.net/password/hash_md5_sha
在线sha1/sha224/sha256/sha384/sha512加密工具：

http://tools.jb51.net/password/sha_encode
更多关于PHP相关内容感兴趣的读者可查看本站专题：《php加密方法总结》、《PHP编码与转码操作技巧汇总》、《PHP数学运算技巧总结》、《PHP数组(Array)操作技巧大全》、《php字符串(string)用法总结》、《PHP数据结构与算法教程》、《php程序设计算法总结》及《php正则表达式用法总结》
希望本文所述对大家PHP程序设计有所帮助。