A reversible encryption function authcode function code in center UCenter

Copy code The code is as follows:

function authcode($string, $operation = 'DECODE', $key = '', $expiry = 0) {
$ckey_length = 4; // Random key length Value 0-32;
// Adding a random key can make the ciphertext irregular. Even if the original text and key are exactly the same, the encryption result will be different every time, making it more difficult to crack.
// The larger the value, the greater the ciphertext change pattern. The ciphertext change = 16 to the power of $ckey_length
// When this value is 0, no random key will be generated
$key = md5($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)) ;
}
}
/***************************************************************************/
$string = authcode("Hello","ENCODE","HTML_TCCJ_AUTH");
echo $string,'
';
echo authcode ($string,"DECODE","HTML_TCCJ_AUTH"),'
';

The above introduces the authcode function code of a reversible encryption function in center UCenter, including the center content. I hope it will be helpful to friends who are interested in PHP tutorials.