// Reversible encryption function - Function authcode ($ string, $ operation = 'Decode', $ key = '', $ expiry = 0 ){
$ 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: 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 (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 ));
- }
- }
// Call example - $ String = authcode ("Hello", "ENCODE", "HTML_TCCJ_AUTH ");
- Echo $ string ,'
';
- Echo authcode ($ string, "DECODE", "HTML_TCCJ_AUTH "),'
';
- ?>
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