/*
*功能：对字符串进行加密处理
*参数一：需要加密的内容
*参数二：密钥
*/
function passport_encrypt($str,$key){ //加密函数
 srand((double)microtime() * 1000000);
 $encrypt_key=md5(rand(0, 32000));
 $ctr=0;
 $tmp='';
 for($i=0;$i<strlen($str);$i++){
  $ctr=$ctr==strlen($encrypt_key)?0:$ctr;
  $tmp.=$encrypt_key[$ctr].($str[$i] ^ $encrypt_key[$ctr++]);
 }
 return base64_encode(passport_key($tmp,$key));
}

/*
*功能：对字符串进行解密处理
*参数一：需要解密的密文
*参数二：密钥
*/
function passport_decrypt($str,$key){ //解密函数
 $str=passport_key(base64_decode($str),$key);
 $tmp='';
 for($i=0;$i<strlen($str);$i++){
  $md5=$str[$i];
  $tmp.=$str[++$i] ^ $md5;
 }
 return $tmp;
}

/*
*辅助函数
*/
function passport_key($str,$encrypt_key){
 $encrypt_key=md5($encrypt_key);
 $ctr=0;
 $tmp='';
 for($i=0;$i<strlen($str);$i++){
  $ctr=$ctr==strlen($encrypt_key)?0:$ctr;
  $tmp.=$str[$i] ^ $encrypt_key[$ctr++];
 }
 return $tmp;
}

$str='作者：www.jb51.net';
$key='123456';
$encrypt=passport_encrypt($str,$key);
$decrypt=passport_decrypt($encrypt,$key);
echo '原文：',$str."<br><hr>";
echo '密文：',$encrypt."<br><hr>";
echo '译文：',$decrypt."<br><hr>";

<?php
class DES
{
 var $key;
 var $iv; //偏移量
 
 function DES( $key, $iv=0 ) {
 //key长度8例如:1234abcd
  $this->key = $key;
  if( $iv == 0 ) {
   $this->iv = $key;
  } else {
   $this->iv = $iv; //mcrypt_create_iv ( mcrypt_get_block_size (MCRYPT_DES, MCRYPT_MODE_CBC), MCRYPT_DEV_RANDOM );
  }
 }
 
 function encrypt($str) {
 //加密，返回大写十六进制字符串
  $size = mcrypt_get_block_size ( MCRYPT_DES, MCRYPT_MODE_CBC );
  $str = $this->pkcs5Pad ( $str, $size );
  return strtoupper( bin2hex( mcrypt_cbc(MCRYPT_DES, $this->key, $str, MCRYPT_ENCRYPT, $this->iv ) ) );
 }
 
 function decrypt($str) {
 //解密
  $strBin = $this->hex2bin( strtolower( $str ) );
  $str = mcrypt_cbc( MCRYPT_DES, $this->key, $strBin, MCRYPT_DECRYPT, $this->iv );
  $str = $this->pkcs5Unpad( $str );
  return $str;
 }
 
 function hex2bin($hexData) {
  $binData = "";
  for($i = 0; $i < strlen ( $hexData ); $i += 2) {
   $binData .= chr ( hexdec ( substr ( $hexData, $i, 2 ) ) );
  }
  return $binData;
 }
 
 function pkcs5Pad($text, $blocksize) {
  $pad = $blocksize - (strlen ( $text ) % $blocksize);
  return $text . str_repeat ( chr ( $pad ), $pad );
 }
 
 function pkcs5Unpad($text) {
  $pad = ord ( $text {strlen ( $text ) - 1} );
  if ($pad > strlen ( $text ))
   return false;
  if (strspn ( $text, chr ( $pad ), strlen ( $text ) - $pad ) != $pad)
   return false;
  return substr ( $text, 0, - 1 * $pad );
 }
}
?>

$str = '12345678';
$key = '1234abcd';
$crypt = new DES($key);
$mstr = $crypt->encrypt($str);
$str = $crypt->decrypt($mstr);
echo  $str.' <=> '.$mstr;

/**
*加密需通过get方式在url中传递的参数
*/
function args_encode($data) {
if(is_array($data)) {
$string = http_build_query($data);
return base64_encode($string);
} else {
return false;
}
}

/**
*获取url中get方式传递的参数
*/
function getargs() {
$string = base64_decode($_GET['args']);
parse_str($string,$g);
return $g;
}