How to use the discuz encryption and decryption function and the Chinese annotation_php tutorial

The usage of the discuz encryption and decryption function and the Chinese comments. Copy the code as follows :? Php *** $ string plaintext or ciphertext * $ operation encryption ENCODE or decryption DECODE * $ key * $ expiry key validity period * functionauthcode ($ string, $ operat The code is as follows:

/**
* $ String plaintext or ciphertext
* $ Operation encrypts the ENCODE or decrypts the DECODE
* $ Key
* $ Expiry key validity period
*/
Function authcode ($ string, $ operation = 'Decode', $ key = '', $ expiry = 0 ){
// The length of the dynamic key. different ciphertext values are generated for the same plaintext based on the dynamic key.
// 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
$ Ckey_length = 4;

// Key
// $ GLOBALS ['discuz _ auth_key '] can be modified as needed.
$ Key = md5 ($ key? $ Key: $ GLOBALS ['discuz _ auth_key ']);

// Key a is used for encryption and decryption.
$ Keya = md5 (substr ($ key, 0, 16 ));
// Key B is used for data integrity verification.
$ Keyb = md5 (substr ($ key, 16, 16 ));
// Key c is used to change the generated ciphertext
$ Keyc = $ ckey_length? ($ Operation = 'decode '? Substr ($ string, 0, $ ckey_length): substr (md5 (microtime (),-$ ckey_length )):'';
// Key used for calculation
$ Cryptkey = $ keya. md5 ($ keya. $ keyc );
$ Key_length = strlen ($ cryptkey );
// Plaintext. the first 10 digits are used to save the timestamp. data validity is verified during decryption, and 10 to 26 digits are used to save $ keyb (key B). Data integrity is verified through this key during decryption.
// If it is decoded, it starts from the $ ckey_length bit, because the $ ckey_length bit before the ciphertext stores the dynamic key to ensure correct decryption.
$ 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 ();
// Generate a key book
For ($ I = 0; $ I <= 255; $ I ++ ){
$ Rndkey [$ I] = ord ($ cryptkey [$ I % $ key_length]);
}
// Use a fixed algorithm to disrupt the key book and increase randomness. it seems complicated. In fact, it does not increase the ciphertext strength.
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;
}
// Core encryption/decryption part
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;
// The Keys obtained from the key book are different or converted into characters.
$ Result. = chr (ord ($ string [$ I]) ^ ($ box [($ box [$ a] + $ box [$ j]) % 256]);
}
If ($ operation = 'decode '){
// Substr ($ result, 0, 10) = 0 verify data validity
// Substr ($ result, 0, 10)-time ()> 0 to verify data validity
// Substr ($ result, 10, 16) = substr (md5 (substr ($ result, 26). $ keyb), 0, 16) verify data integrity
// Verify the data validity. see the unencrypted plaintext format.
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 {
// Save the dynamic key in the ciphertext, which is why different ciphertext can be decrypted in the same plain text.
// Because the encrypted ciphertext may be special characters, the copying process may be lost, so it is Base64-encoded.
Return $ keyc. str_replace ('=', '', base64_encode ($ result ));
}
}

$ A = www.jb51.net;
$ B = authcode ($ a, "ENCODE", "abc123 ");
Echo $ B ."
";
Echo authcode ($ B, "DECODE", "abc123 ");
?>

The http://www.bkjia.com/PHPjc/726030.htmlwww.bkjia.comtruehttp://www.bkjia.com/PHPjc/726030.htmlTechArticle code is as follows :? Php/*** $ string plaintext or ciphertext * $ operation encryption ENCODE or decryption DECODE * $ key * $ expiry key validity period */function authcode ($ string, $ operat...