Classic PHP encryption and decryption function Authcode() repair version code

Classic PHP encryption and decryption function Authcode() repair version code_PHP tutorial

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Release： 2016-07-13 09:57:58

Original

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Repair code of the classic PHP encryption and decryption function Authcode()

Authcode is a function that many people use. This function comes from the Discuz program and is used to encrypt and decrypt strings. You can set the key (key) and expiration time are useful in many cases. The original function code may generate characters such as , /, &, which will cause them to be escaped when the value is returned through the URL, making it impossible to decrypt. Fireend Network made a slight modification, replaced these characters with other characters, and then replaced them back during decryption, so it was 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('0d', $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;

}

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