Authcode这个函数很多人都使用，这函数来自Discuz程序，用于加密解密字符串，可以设置钥匙(key)和过期时间，在很多时候都用得着。原版的函数代码可能会生成+、/、&这样的字符，导致通过URL传值取回时被转义，导致无法解密。稍加修改，把这几个字符替换成其它字符，解密时再替换回去，这样就完美了!
代码如下：
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; $i 0) && substr($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;
}
}
