<?php
/**
 * 常用对称加密算法类
 * 支持密钥：64/128/256 bit（字节长度8/16/32）
 * 支持算法：DES/AES（根据密钥长度自动匹配使用：DES:64bit AES:128/256bit）
 * 支持模式：CBC/ECB/OFB/CFB
 * 密文编码：base64字符串/十六进制字符串/二进制字符串流
 * 填充方式: PKCS5Padding（DES）
 *
 * @author: linvo
 * @version: 1.0.0
 * @date: 2013/1/10
 */
class Xcrypt{
	
	private $mcrypt;
	private $key;
	private $mode;
	private $iv;
	private $blocksize;
	
	/**
	 * 构造函数
	 *
	 * @param string 密钥
	 * @param string 模式
	 * @param string 向量（"off":不使用 / "auto":自动 / 其他:指定值，长度同密钥）
	 */
	public function __construct($key, $mode = 'cbc', $iv = "off"){
		switch (strlen($key)){
			case 8:
				$this->mcrypt = MCRYPT_DES;
				break;
			case 16:
				$this->mcrypt = MCRYPT_RIJNDAEL_128;
				break;
			case 32:
				$this->mcrypt = MCRYPT_RIJNDAEL_256;
				break;
			default:
				die("Key size must be 8/16/32");
		}
		
		$this->key = $key;
		
		switch (strtolower($mode)){
			case 'ofb':
				$this->mode = MCRYPT_MODE_OFB;
				if ($iv == 'off') die('OFB must give a IV'); //OFB必须有向量
				break;
			case 'cfb':
				$this->mode = MCRYPT_MODE_CFB;
				if ($iv == 'off') die('CFB must give a IV'); //CFB必须有向量
				break;
			case 'ecb':
				$this->mode = MCRYPT_MODE_ECB;
				$iv = 'off'; //ECB不需要向量
				break;
			case 'cbc':
			default:
				$this->mode = MCRYPT_MODE_CBC;
		}
		
		switch (strtolower($iv)){
			case "off":
				$this->iv = null;
				break;
			case "auto":
				$source = PHP_OS=='WINNT' ? MCRYPT_RAND : MCRYPT_DEV_RANDOM;
				$this->iv = mcrypt_create_iv(mcrypt_get_block_size($this->mcrypt, $this->mode), $source);
				break;
			default:
				$this->iv = $iv;
		}
		
	}
	
	/**
	 * 获取向量值
	 * @param string 向量值编码（base64/hex/bin）
	 * @return string 向量值
	 */
	public function getIV($code = 'base64'){
		switch ($code){
			case 'base64':
				$ret = base64_encode($this->iv);
				break;
			case 'hex':
				$ret = bin2hex($this->iv);
				break;
			case 'bin':
			default:
				$ret = $this->iv;
		}
		return $ret;
	}
	
	/**
	 * 加密
	 * @param string 明文
	 * @param string 密文编码（base64/hex/bin）
	 * @return string 密文
	 */
	public function encrypt($str, $code = 'base64'){
		if ($this->mcrypt == MCRYPT_DES) $str = $this->_pkcs5Pad($str);
		
		if (isset($this->iv)) {
			$result = mcrypt_encrypt($this->mcrypt, $this->key, $str, $this->mode, $this->iv);
		} else {
			@$result = mcrypt_encrypt($this->mcrypt, $this->key, $str, $this->mode);
		}
		
		switch ($code){
			case 'base64':
				$ret = base64_encode($result);
				break;
			case 'hex':
				$ret = bin2hex($result);
				break;
			case 'bin':
			default:
				$ret = $result;
		}
		
		return $ret;
		
	}
	
	/**
	 * 解密
	 * @param string 密文
	 * @param string 密文编码（base64/hex/bin）
	 * @return string 明文
	 */
	public function decrypt($str, $code = "base64"){
		$ret = false;
		
		switch ($code){
			case 'base64':
				$str = base64_decode($str);
				break;
			case 'hex':
				$str = $this->_hex2bin($str);
				break;
			case 'bin':
			default:
		}
		
		if ($str !== false){
			if (isset($this->iv)) {
				$ret = mcrypt_decrypt($this->mcrypt, $this->key, $str, $this->mode, $this->iv);
			} else {
				@$ret = mcrypt_decrypt($this->mcrypt, $this->key, $str, $this->mode);
			}
			if ($this->mcrypt == MCRYPT_DES) $ret = $this->_pkcs5Unpad($ret);
		}
		
		return $ret;
	}
	
	private function _pkcs5Pad($text){
		$this->blocksize = mcrypt_get_block_size($this->mcrypt, $this->mode);
		$pad = $this->blocksize - (strlen($text) % $this->blocksize);
		return $text . str_repeat(chr($pad), $pad);
	}
	
	private 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;
		$ret = substr($text, 0, -1 * $pad);
		return $ret;
	}
	
	private function _hex2bin($hex = false){
		$ret = $hex !== false && preg_match('/^[0-9a-fA-F]+$/i', $hex) ? pack("H*", $hex) : false;
		return $ret;
	}
	
}