PHP source code analysis of DZX1.5 encryption and decryption function authcode usage

PHP source code analysis of DZX1.5 encryption and decryption function authcode usage_PHP tutorial

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Release： 2016-07-13 09:50:04

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Usage of DZX1.5 encryption and decryption function authcode in php source code analysis

This article describes the usage of DZX1.5 encryption and decryption function authcode in php source code analysis. Share it with everyone for your reference. The specific analysis is as follows:

$authkey = '';

/**

* @param string $string: The input plaintext (or ciphertext) that needs to be encrypted (or decrypted)

* @param string $operation: 'DECODE' or other, the default means decryption, input other means encryption

* @param string $key: encryption and decryption key

* @param int $expiry: Validity period

function authcode($string, $operation = 'DECODE', $key = '', $expiry = 0) {

global $authkey;

$ckey_length = 4;

$key = md5($key != '' ? $key : $authkey);

$keya = md5(substr($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 {

return $keyc.str_replace('=', '', base64_encode($result));

}

$str = '1234';

$key = '1234';

echo "plain text:".$str;

echo "
";

echo "Key:".$key;