Classic PHP encryption and decryption function Authcode () fixed version code, encryption and decryption authcode_PHP tutorial

The classic PHP encryption and decryption function Authcode () fixes the version code and encrypts and decrypts the authcode. The classic PHP encryption and decryption function Authcode () fixes the version code. encryption and decryption are used by many people. This function is used by the Discuz program to encrypt and decrypt strings, you can use the classic PHP encryption and decryption function Authcode () to fix the code and encrypt and decrypt the authcode.

Many people use the Authcode function. this function comes from the Discuz program and is used to encrypt and decrypt strings. it can be used to set the key and Expiration Time. The original function code may generate characters such as +,/, and &. as a result, the function code is escaped when the value is retrieved through the URL and cannot be decrypted. The network on the fire end is slightly modified. replace these characters with other characters, and then replace them with each other during decryption. this is perfect!

The code is as follows:

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; }}

Encrypt () fixed version code, encryption and decryption authcode this function is used by many people, this function is from the Discuz program, used to encrypt and decrypt strings, can...