Authcode這個(gè)函數(shù)很多人都使用，這函數(shù)來自Discuz程序，用于加密解密字符串，可以設(shè)置鑰匙（key）和過期時(shí)間，在很多時(shí)候都用得著。原版的函數(shù)代碼可能會(huì)生成+、/、&這樣的字符，導(dǎo)致通過URL傳值取回時(shí)被轉(zhuǎn)義，導(dǎo)致無法解密?；鸲司W(wǎng)絡(luò)稍加修改，把這幾個(gè)字符替換成其它字符，解密時(shí)再替換回去，這樣就完美了！
代碼如下:
function authcode($string, $operation = 'DECODE', $key = '', $expiry = 0){
if($operation == 'DECODE') {
$string = str_replace('[a]','+',$string);
$string = str_replace('[b]','&',$string);
$string = str_replace('[c]','/',$string);
}
$ckey_length = 4;
$key = md5($key ? $key : 'livcmsencryption ');
$keya = md5(substr($key, 0, 16));
$keyb = md5(substr($key, 16, 16));
$keyc = $ckey_length ? ($operation == 'DECODE' ? substr($string, 0, $ckey_length): substr(md5(microtime()), -$ckey_length)) : '';
$cryptkey = $keya.md5($keya.$keyc);
$key_length = strlen($cryptkey);
$string = $operation == 'DECODE' ? base64_decode(substr($string, $ckey_length)) : sprintf('%010d', $expiry ? $expiry + time() : 0).substr(md5($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 % $key_length]);
}
for($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]));
}
if($operation == 'DECODE') {
if((substr($result, 0, 10) == 0 || substr($result, 0, 10) - time() > 0) && substr($result, 10, 16) == substr(md5(substr($result, 26).$keyb), 0, 16)) {
return substr($result, 26);
} else {
return '';
}
} else {
$ustr = $keyc.str_replace('=', '', base64_encode($result));
$ustr = str_replace('+','[a]',$ustr);
$ustr = str_replace('&','[b]',$ustr);
$ustr = str_replace('/','[c]',$ustr);
return $ustr;
}
}