PHP string encryption function (restores strings encrypted within a specified period of time and cannot be restored upon timeout) _ PHP Tutorial

PHP string encryption function (restores strings encrypted within the specified time, and cannot be restored upon timeout ). In this way, we can use this function for many purposes, such as the token encrypted transmission of single sign-on, temporary password, and so on. copy the code as follows: * ** @ paramstring $ string we can use this function for many purposes, such as encrypted transmission of tokens for single sign-on and temporary passwords.

The code is as follows:

/**
* @ Param string $ string original text or ciphertext
* @ Param string $ operation (ENCODE | DECODE). The default value is DECODE.
* @ Param string $ key
* @ Param int $ expiry ciphertext validity period. Valid during encryption. unit: Seconds. 0 indicates permanent validity.
* @ Return string the original text after processing or the ciphertext after base64_encode processing
*
* @ Example
*
* $ A = authcode ('ABC', 'encode', 'key ');
* $ B = authcode ($ a, 'Decode', 'key'); // $ B (abc)
*
* $ A = authcode ('ABC', 'encode', 'key', 3600 );
* $ B = authcode ('ABC', 'Decode', 'key'); // within an hour, $ B (abc); otherwise, $ B is empty.
*/
Function authcode ($ string, $ operation = 'Decode', $ key = '', $ expiry = 3600 ){
$ Ckey_length = 4;
// The random key length ranges from 0 to 32;
// Adding a random key can make the ciphertext irregular. even if the original text and the key are identical, the encryption results will be different each time, increasing the difficulty of cracking.
// The larger the value, the larger the ciphertext change law. The ciphertext change is equal to the power of $ ckey_length of 16.
// When this value is 0, no random key is generated
$ Key = md5 ($ key? $ Key: EABAX: getAppInf ('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 (1, 0,255 );
$ Rndkey = array ();
For ($ I = 0; $ I <= 255; $ I ++ ){
$ Rndkey [$ I] = ord ($ cryptkey [$ I % $ key_length]);
}
For ($ j = $ I = 0; I 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 ));
}
}

The pipeline code is as follows:/*** @ param string $ string original...