php 用户验证 base64验证方法

php教程 用户验证 base64验证方法
//cookie处理
function dsetcookie($var, $value, $life = 0, $prefix = 1) {
global $cookiedomain, $cookiepath, $addtime, $_server;
setcookie($var, $value,$life ? $addtime + $life : 0, $cookiepath,$cookiedomain, $_server['server_port'] == 443 ? 1 : 0);
}

function authcode($string, $operation = 'decode', $key = '', $expiry = 0) {
global $webaddr;
$auth_key=md5($webaddr);
$ckey_length = 4;
$key = md5($key ? $key : $auth_key);
$keya = md5(substr($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 $rndkey[$i] = ord($cryptkey[$i % $key_length]);
}
for($j = $i = 0; $i $j = ($j + $box[$i] + $rndkey[$i]) % 256;
$tmp = $box[$i];
$box[$i] = $box[$j];
$box[$j] = $tmp;
}
for($a = $j = $i = 0; $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 {
return $keyc.str_replace('=', '', base64_encode($result));
}
}
?>