Example of XXTEA Encryption and Decryption Algorithm Realized by PHP

This paper describes the encryption and decryption algorithm of XXTEA realized by PHP. Share it for your reference, as follows:

<?php
/**
 * Xxtea  Encryption implementation class 
 */
class xxtea {
  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]);
    return $w ? substr(implode('', $s), 0, $n) : implode('', $s);
  }
  private function str2long($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) $n;
  }
  public function encrypt($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);
  }
}
// Usage test: 
$strDemo = "www.ofstack.com";
$key = "123456";
$pwd = new Xxtea();
$pwdrel = $pwd->encrypt($strDemo, $key);
echo $pwdrel;
echo "<br/>";
echo $pwd->decrypt($pwdrel, $key);
?>

Run results:

{���H(�S��7*�u7U
www.ofstack.com

PS: Friends who are interested in encryption and decryption can also refer to the online tools of this site:

Online RSA Encryption/Decryption Tool:
http://tools.ofstack.com/password/rsa_encode

Text online encryption and decryption tools (including AES, DES, RC4, etc.):
http://tools.ofstack.com/password/txt_encode

Online hash/hash algorithm encryption tool:
http://tools.ofstack.com/password/hash_encrypt

Online MD5/hash/SHA-1/SHA-2/SHA-256/SHA-512/SHA-3/RIPEMD-160 Encryption Tool:
http://tools.ofstack.com/password/hash_md5_sha

Online sha1/sha224/sha256/sha384/sha512 Encryption Tool:
http://tools.ofstack.com/password/sha_encode

For more readers interested in PHP related contents, please check the special topics of this site: "Summary of php Encryption Methods", "Summary of PHP Encoding and Transcoding Operation Skills", "Summary of PHP Mathematical Operation Skills", "Encyclopedia of PHP Array (Array) Operation Skills", "Summary of php String (string) Usage", "Tutorial of PHP Data Structure and Algorithm", "Summary of php Programming Algorithm" and "Summary of php Regular Expression Usage"

I hope this article is helpful to everyone's PHP programming.