php 加密解密方法

<?php
//可用于加密解密，如cookie，账号，手机号 as so on
class DES
{
	var $key;
	var $iv; //偏移量
	
	function __construct( $key, $iv=0 ) {
	//key长度8例如:1234abcd
		$this->key = $key;
		if( $iv == 0 ) {
			$this->iv = $key; //默认以$key 作为 iv
		} 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 );
	}
	
}
// 实例化，并传入两个参数，都为8位,即 KEY, VI的值
$des = new DES('abcd1234', '87654321');
//加密结果 $aa 为 7A3C7BBA8B42ADC4
$str = '123456';
$aa = $des->encrypt($str);
echo $aa;
// 解密结果 $bb 为 123456
$bb = $des->decrypt($aa);
echo $bb;
?>