Two classic PHP encryption and decryption functions-PHP Tutorial

Two classic PHP encryption and decryption functions. In projects, we sometimes need to use PHP to encrypt specific information, that is, to generate an encrypted string through the encryption algorithm, this encrypted string can be used in projects through the decryption algorithm. sometimes we need to use PHP to encrypt specific information, that is, to generate an encrypted string through the encryption algorithm, the encrypted string can be decrypted through the decryption algorithm, so that the program can process the decrypted information.
The most common applications are user logon and some API data exchange scenarios.

I have collected some classic PHP encryption and decryption function code and shared it with you. Encryption and decryption principles are generally based on a certain number of encryption and decryption algorithms, add the key to the algorithm, and finally obtain the encryption and decryption results.
1. very powerful authcode encryption function, Discuz! Classic code (detailed description ):

The code is as follows:

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.
$ Ckey_length = 4;

// Key
$ 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, verify the data validity during decryption, and the 10 to 26 digits are used to save $ keyb (key B ),
// This key is used to verify data integrity 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 '){
// 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 ));
}
}

$ String: string, plaintext or ciphertext in the authcode ($ string, $ operation, $ key, $ expiry) function; $ operation: DECODE indicates decryption; others indicate encryption; $ key: key; $ expiry: ciphertext validity period.

Usage:

The code is as follows:

$ Str = 'abcdef ';
$ Key = 'www .helloweba.com ';
Echo authcode ($ str, 'encoding', $ key, 0); // encryption
$ Str = '56f4yer1di2wtzwmqsfpps9hwyojnfp2mpc8sohrrxo7bok ';
Echo authcode ($ str, 'Decode', $ key, 0); // decrypt

2. encryption and decryption function encrypt ():

The code is as follows:

Function encrypt ($ string, $ operation, $ key = ''){
$ Key = md5 ($ key );
$ Key_length = strlen ($ key );
$ String = $ operation = 'D '? Base64_decode ($ string): substr (md5 ($ string. $ key), 0, 8). $ string;
$ String_length = strlen ($ string );
$ Rndkey = $ box = array ();
$ Result = '';
For ($ I = 0; $ I <= 255; $ I ++ ){
$ Rndkey [$ I] = ord ($ key [$ I % $ key_length]);
$ Box [$ I] = $ I;
}
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 = 'd '){
If (substr ($ result,) = substr (md5 (substr ($ result, 8). $ key )){
Return substr ($ result, 8 );
} Else {
Return '';
}
} Else {
Return str_replace ('=', '', base64_encode ($ result ));
}
}

$ String in the encrypt ($ string, $ operation, $ key) function: the string to be encrypted and decrypted; $ operation: determines whether the string is encrypted or decrypted. E indicates encryption, and D indicates decryption; $ key: the key.
Usage:

The code is as follows:

$ Str = 'abc ';
$ Key = 'www .helloweba.com ';
$ Token = encrypt ($ str, 'e', $ key );
Echo 'encryption: '. encrypt ($ str, 'e', $ key );
Echo 'decryption: '. encrypt ($ str, 'D', $ key );

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