//可逆的加密函數 - function authcode($string, $operation = 'DECODE', $key = '', $expiry = 0) {
$ckey_length = 4; // 隨機密鑰長度 取值 0-32; - // 加入隨機密鑰，可以令密文無任何規律，即便是原文和密鑰完全相同，加密結果也會每次不同，增大破解難度。
- // 取值越大，密文變動規律越大，密文變化 = 16 的 $ckey_length 次方
- // 當此值為 0 時，則不產生隨機密鑰
- $key = md5($key ? $key : UC_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 <= 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 {
- return $keyc.str_replace('=', '', base64_encode($result));
- }
- }
//調用樣本 - $string = authcode("Hello","ENCODE","HTML_TCCJ_AUTH");
- echo $string,'
';
- echo authcode($string,"DECODE","HTML_TCCJ_AUTH"),'
';
- ?>
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