Example of php encryption and decryption with a key

This article mainly introduces the example of php encryption and decryption. For more information, see.

This article mainly introduces the example of php encryption and decryption. For more information, see.

The Code is as follows:

$ Id = "http://www.jb51.net ";
$ Token = encrypt ($ id, 'E', 'jb51 ');
Echo 'encryption: '. encrypt ($ id, 'E', 'jb51 ');
Echo'
';
Echo 'decryption: '. encrypt ($ token, 'D', 'jb51 ');

/*************************************** ******************************
Function Name: encrypt
Function: encrypts and decrypts strings.
Usage:
Encryption: encrypt ('str', 'E', 'qingdou ');
Decryption: encrypt ('encrypted string', 'D', 'qingdou ');
Parameter description:
$ String: string to be encrypted and decrypted
$ Operation: Determine whether to encrypt or decrypt: E: encrypt D: decrypt
$ Key: the Encrypted key (key );
**************************************** *****************************/
Function encrypt ($ string, $ operation, $ key = '')
{
$ Src = array ("/", "+", "= ");
$ Dist = array ("_ a", "_ B", "_ c ");
If ($ operation = 'D') {$ string = str_replace ($ dist, $ src, $ string );}
$ 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
{
$ Rdate = str_replace ('=', '', base64_encode ($ result ));
$ Rdate = str_replace ($ src, $ dist, $ rdate );
Return $ rdate;
}
}
?>

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