blowfish.h

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/*
**  Command & Conquer Generals Zero Hour(tm)
**  Copyright 2025 Electronic Arts Inc.
**
**  This program is free software: you can redistribute it and/or modify
**  it under the terms of the GNU General Public License as published by
**  the Free Software Foundation, either version 3 of the License, or
**  (at your option) any later version.
**
**  This program is distributed in the hope that it will be useful,
**  but WITHOUT ANY WARRANTY; without even the implied warranty of
**  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
**  GNU General Public License for more details.
**
**  You should have received a copy of the GNU General Public License
**  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
 
/*********************************************************************************************** 
 ***              C O N F I D E N T I A L  ---  W E S T W O O D  S T U D I O S               *** 
 *********************************************************************************************** 
 *                                                                                             * 
 *                 Project Name : Command & Conquer                                            * 
 *                                                                                             * 
 *                     $Archive:: /Commando/Library/BLOWFISH.H                                $* 
 *                                                                                             * 
 *                      $Author:: Greg_h                                                      $*
 *                                                                                             * 
 *                     $Modtime:: 7/22/97 11:37a                                              $*
 *                                                                                             * 
 *                    $Revision:: 1                                                           $*
 *                                                                                             *
 *---------------------------------------------------------------------------------------------* 
 * Functions:                                                                                  * 
 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 
#ifndef BLOWFISH_H
#define BLOWFISH_H
 
#include    <limits.h>
 
 
/*
**  The "bool" integral type was defined by the C++ committee in
**  November of '94. Until the compiler supports this, use the following
**  definition.
*/
#include    "bool.h"
 
 
/*
**  This engine will process data blocks by encryption and decryption.
**  The "Blowfish" algorithm is in the public domain. It uses
**  a Feistal network (similar to IDEA). It has no known
**  weaknesses, but is still relatively new. Blowfish is particularly strong
**  against brute force attacks. It is also quite strong against linear and
**  differential cryptanalysis. Unlike public key encription, it is very
**  fast at encryption, as far as cryptography goes. Its weakness is that 
**  it takes a relatively long time to set up with a new key (1/100th of 
**  a second on a P6-200). The time to set up a key is equivalent to 
**  encrypting 4240 bytes.
*/
class BlowfishEngine {
    public:
        BlowfishEngine(void) : IsKeyed(false) {}
        ~BlowfishEngine(void);
 
        void Submit_Key(void const * key, int length);
 
        int Encrypt(void const * plaintext, int length, void * cyphertext);
        int Decrypt(void const * cyphertext, int length, void * plaintext);
 
        /*
        **  This is the maximum key length supported.
        */
        enum {MAX_KEY_LENGTH=56};
 
    private:
        bool IsKeyed;
 
        void Sub_Key_Encrypt(unsigned long & left, unsigned long & right);
 
        void Process_Block(void const * plaintext, void * cyphertext, unsigned long const * ptable);
        void Initialize_Tables(void);
 
        enum {
            ROUNDS = 16,        // Feistal round count (16 is standard).
            BYTES_PER_BLOCK=8   // The number of bytes in each cypher block (don't change).
        };
 
        /*
        **  Initialization data for sub keys. The initial values are constant and
        **  filled with a number generated from pi. Thus they are not random but
        **  they don't hold a weak pattern either.
        */
        static unsigned long const P_Init[ROUNDS+2];
        static unsigned long const S_Init[4][UCHAR_MAX+1];
 
        /*
        **  Permutation tables for encryption and decryption.
        */
        unsigned long P_Encrypt[ROUNDS+2];
        unsigned long P_Decrypt[ROUNDS+2];
 
        /*
        **  S-Box tables (four).
        */
        unsigned long bf_S[4][UCHAR_MAX+1];
};
 
#endif