farm/mazephp/.svn/pristine/66/6682efd9272b3950838484b14c0efe818f09b30a.svn-base

<?php namespace Maze\Security;

class Internal
{
	/**
     * key
     *
     * @var string
     */
    static private $key = 'qwertyuiop12345asdfghjkl67890zxcvbnm';
    
	/**
     * encode
     * @param  string  $string
     * @param  string  $key
     * 
     * @return string
     */
	static public function encode($string, $key="")
	{
		$ckey_length = 5;
		
		if(!$key) $key = md5(self::$key);
		
		$keya = md5(substr($key, 0, 16));
		$keyb = md5(substr($key, 16, 16));
		$keyc = $ckey_length ? substr(md5(microtime()), -$ckey_length) : '';//md5串后4位，每次不一样

		$cryptkey = $keya.md5($keya.$keyc);//两个md5串
		$key_length = strlen($cryptkey);//64

		$string = sprintf('%010d', time()).substr(md5($string.$keyb), 0, 16).$string;
		$string_length = strlen($string);

		$result = '';
		$box = range(0, 255);

		$rndkey = array();
		for($i = 0; $i <= 255; $i++) 
		{
			$rndkey[$i] = ord($cryptkey[$i % $key_length]);//生成一个255个元素的数组
		}

		for($j = $i = 0; $i < 256; $i++)
		{
			//将$box数组转换为无序并且个数不变的数据
			$j = ($j + $box[$i] + $rndkey[$i]) % 256;
			$tmp = $box[$i];
			$box[$i] = $box[$j];
			$box[$j] = $tmp;
		}

		for($a = $j = $i = 0; $i < $string_length; $i++) 
		{
			$a = ($a + 1) % 256;
			$j = ($j + $box[$a]) % 256;
			$tmp = $box[$a];
			$box[$a] = $box[$j];
			$box[$j] = $tmp;
			$result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));
		}
		
		return $keyc.str_replace('=', '', self::base64_encode($result));

	}

	/**
     * decode
     * @param  string  $string
     * @param  string  $key
     * 
     * @return string
     */
	static public function decode($string, $key="")
	{
		$ckey_length = 5;
		
		if(!$key) $key = md5(self::$key);
		
		$keya = md5(substr($key, 0, 16));
		$keyb = md5(substr($key, 16, 16));
		$keyc = $ckey_length ? substr($string, 0, $ckey_length) : '';//和encrypt时的$keyc一样

		$cryptkey = $keya.md5($keya.$keyc);
		$key_length = strlen($cryptkey);

		$string =  self::base64_decode(substr($string, $ckey_length)) ;
		$string_length = strlen($string);

		$result = '';
		$box = range(0, 255);

		$rndkey = array();
		for($i = 0; $i <= 255; $i++) 
		{
			$rndkey[$i] = ord($cryptkey[$i % $key_length]);
		}

		for($j = $i = 0; $i < 256; $i++) 
		{
			//和encrypt时的$box一样
			$j = ($j + $box[$i] + $rndkey[$i]) % 256;
			$tmp = $box[$i];
			$box[$i] = $box[$j];
			$box[$j] = $tmp;
		}

		for($a = $j = $i = 0; $i < $string_length; $i++)
		{
			//核心操作，解密
			$a = ($a + 1) % 256;
			$j = ($j + $box[$a]) % 256;
			$tmp = $box[$a];
			$box[$a] = $box[$j];
			$box[$j] = $tmp;
			$result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));
		}


		if(substr($result, 10, 16) == substr(md5(substr($result, 26).$keyb), 0, 16)) 
		{
			return substr($result, 26);
		}
		else 
		{
			return '';
		}

	}
	
	/**
     * base64_encode
     * @param  string  $string
     * 
     * @return string
     */
	static function base64_encode($string)
	{
		if(!$string)
		{
			return false;
		}
		$encodestr = base64_encode($string);
		$encodestr = str_replace(array('+','/'),array('-','_'),$encodestr);
		return $encodestr;
	}
	
	/**
     * base64_decode
     * @param  string  $string
     * 
     * @return string
     */
	static function base64_decode($string)
	{
		if(!$string)
		{
			return false;
		}
		$string = str_replace(array('-','_'),array('+','/'),$string);
		$decodestr = base64_decode($string);		
		return $decodestr;
	}
}