/**
* 加密or解密，来自互联网，类似discuz传递信息
* <code>
* echo $str=edcode('1371817454','ENCODE','1');
* echo edcode('XbfSC2GOpSTtwHwOIDW7Fg','DECODE','2000558');
* </code>
* @param string $string 密文
* @param string $operation 操作类型 DECODE | DECODE
* @param string $key 加密密钥
* @return string
*/
public static function edcode($string, $operation, $key = 'ePHP')
{
//ENCODE
$key_length = strlen($key);
$string = $operation == 'DECODE' ? Func::safe_b64decode($string) : substr(md5($string . $key), 0, 8) . $string;
$string_length = strlen($string);
$rndkey = $box = array();
$result = '';
for ($i = 0; $i <= 255; $i++) {
$rndkey[$i] = ord($key[$i % $key_length]);
$box[$i] = $i;
}
for ($j = $i = 0; $i < 256; $i++) {
$j = ($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]);
}
//DECODE
if ($operation == 'DECODE') {
if (substr($result, 0, 8) == substr(md5(substr($result, 8) . $key), 0, 8)) {
return substr($result, 8);
} else {
return '';
}
} else {
return str_replace('=', '', Func::safe_b64encode($result));
}
}
