/*
** Command & Conquer Red Alert(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/>.
*/
/* $Header: /CounterStrike/RNDSTRAW.CPP 1 3/03/97 10:25a Joe_bostic $ */
/***********************************************************************************************
*** 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 *
* *
* File Name : RNDSTRAW.CPP *
* *
* Programmer : Joe L. Bostic *
* *
* Start Date : 07/04/96 *
* *
* Last Update : July 10, 1996 [JLB] *
* *
*---------------------------------------------------------------------------------------------*
* Functions: *
* RandomStraw::Get -- Fetch random data. *
* RandomStraw::RandomStraw -- Constructor for the random straw class. *
* RandomStraw::Reset -- Reset the data to known initial state. *
* RandomStraw::Scramble_Seed -- Masks any coorelation between the seed bits. *
* RandomStraw::Seed_Bit -- Add a random bit to the accumulated seed value. *
* RandomStraw::Seed_Bits_Needed -- Fetches the number of seed bits needed. *
* RandomStraw::Seed_Byte -- Submit 8 bits to the random number seed. *
* RandomStraw::Seed_Long -- Submit 32 bits to the random number seed. *
* RandomStraw::Seed_Short -- Submit 16 bits to the random number seed. *
* RandomStraw::~RandomStraw -- Destructor for random straw class. *
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
#include <limits.h>
#include <string.h>
#include "rndstraw.h"
#include "sha.h"
/***********************************************************************************************
* RandomStraw::RandomStraw -- Constructor for the random straw class. *
* *
* This will initialize the random straw into a known state. The initial state is useless *
* for cryptographic purposes. It must be seeded before it should be used. *
* *
* INPUT: none *
* *
* OUTPUT: none *
* *
* WARNINGS: none *
* *
* HISTORY: *
* 07/10/1996 JLB : Created. *
*=============================================================================================*/
RandomStraw::RandomStraw(void) :
SeedBits(0),
Current(0)
{
Reset();
}
/***********************************************************************************************
* RandomStraw::~RandomStraw -- Destructor for random straw class. *
* *
* This destructor will clear out the seed data so that there won't be any sensitive *
* information left over in the memory this object occupied. *
* *
* INPUT: none *
* *
* OUTPUT: none *
* *
* WARNINGS: none *
* *
* HISTORY: *
* 07/10/1996 JLB : Created. *
*=============================================================================================*/
RandomStraw::~RandomStraw(void)
{
Reset();
}
/***********************************************************************************************
* RandomStraw::Reset -- Reset the data to known initial state. *
* *
* This routine is functionally equivalent to performing an placement new on the object. It *
* clears out all the seed data. *
* *
* INPUT: none *
* *
* OUTPUT: none *
* *
* WARNINGS: You must reseed it before fetching random numbers. *
* *
* HISTORY: *
* 07/10/1996 JLB : Created. *
*=============================================================================================*/
void RandomStraw::Reset(void)
{
SeedBits = 0;
Current = 0;
memset(Random, '\0', sizeof(Random));
}
/***********************************************************************************************
* RandomStraw::Seed_Bits_Needed -- Fetches the number of seed bits needed. *
* *
* This routine is used when seeding the random straw. Keep feeding random bits to this *
* class until the Seed_Bits_Needed value returns zero. Random bits should be gathered from *
* sources external to the immediate program. Examples would be the system clock (good for *
* a few bits), the delay between player keystrokes (good for a few bits per keystroke), *
* etc. When gathering random bits from integers, use the low order bits (since they *
* characteristically are less predictable and more 'random' than the others). *
* *
* INPUT: none *
* *
* OUTPUT: Returns with the number of bits required in order to fully seed this random *
* number generator. *
* *
* WARNINGS: Even if this routine returns zero, you are still allowed and encouraged to feed *
* more random bits when the opportunity arrises. *
* *
* HISTORY: *
* 07/10/1996 JLB : Created. *
*=============================================================================================*/
int RandomStraw::Seed_Bits_Needed(void) const
{
const int total = sizeof(Random) * CHAR_BIT;
if (SeedBits < total) {
return(total - SeedBits);
}
return(0);
}
/***********************************************************************************************
* RandomStraw::Seed_Bit -- Add a random bit to the accumulated seed value. *
* *
* This routine should be called to feed a single random bit to the random straw object. *
* You must feed as many bits as requested by the Seed_Bits_Needed() function. Submitting *
* additional bits is not only allowed, but encouraged. *
* *
* INPUT: seed -- The bit (lowest order bit) to feed to the random number seed. *
* *
* OUTPUT: none *
* *
* WARNINGS: none *
* *
* HISTORY: *
* 07/10/1996 JLB : Created. *
*=============================================================================================*/
void RandomStraw::Seed_Bit(int seed)
{
char * ptr = ((char *)&Random[0]) + ((SeedBits / CHAR_BIT) % sizeof(Random));
char frac = (char)(1 << (SeedBits & (CHAR_BIT-1)));
if (seed & 0x01) {
*ptr ^= frac;
}
SeedBits++;
if (SeedBits == (sizeof(Random) * CHAR_BIT)) {
Scramble_Seed();
}
}
/***********************************************************************************************
* RandomStraw::Seed_Byte -- Submit 8 bits to the random number seed. *
* *
* This will submit 8 bits (as specified) to the random number seed. *
* *
* INPUT: seed -- The seed bits to submit. *
* *
* OUTPUT: none *
* *
* WARNINGS: none *
* *
* HISTORY: *
* 07/10/1996 JLB : Created. *
*=============================================================================================*/
void RandomStraw::Seed_Byte(char seed)
{
for (int index = 0; index < CHAR_BIT; index++) {
Seed_Bit(seed);
seed >>= 1;
}
}
/***********************************************************************************************
* RandomStraw::Seed_Short -- Submit 16 bits to the random number seed. *
* *
* This will submit 16 bits to the accumulated seed. *
* *
* INPUT: seed -- The 16 bits to submit to the seed. *
* *
* OUTPUT: none *
* *
* WARNINGS: none *
* *
* HISTORY: *
* 07/10/1996 JLB : Created. *
*=============================================================================================*/
void RandomStraw::Seed_Short(short seed)
{
for (int index = 0; index < (sizeof(seed)*CHAR_BIT); index++) {
Seed_Bit(seed);
seed >>= 1;
}
}
/***********************************************************************************************
* RandomStraw::Seed_Long -- Submit 32 bits to the random number seed. *
* *
* This will submit a full 32 bits to the accumulated seed value. *
* *
* INPUT: seed -- The 32 bits to submit. *
* *
* OUTPUT: none *
* *
* WARNINGS: none *
* *
* HISTORY: *
* 07/10/1996 JLB : Created. *
*=============================================================================================*/
void RandomStraw::Seed_Long(long seed)
{
for (int index = 0; index < (sizeof(seed)*CHAR_BIT); index++) {
Seed_Bit(seed);
seed >>= 1;
}
}
/***********************************************************************************************
* RandomStraw::Scramble_Seed -- Masks any coorelation between the seed bits. *
* *
* This routine is called when a full set of seed bits has been accumulated. It will take *
* the existing seed and scramble the bits. An effective way of doing this is to use the *
* Secure Hash Algorithm. It is necessary to have this routine because there might be *
* some coorelation in the seed bits. Even more important is that this routine will result *
* in every bit of the seed having a scrambling effect on every other bit. *
* *
* INPUT: none *
* *
* OUTPUT: none *
* *
* WARNINGS: none *
* *
* HISTORY: *
* 07/10/1996 JLB : Created. *
*=============================================================================================*/
void RandomStraw::Scramble_Seed(void)
{
SHAEngine sha;
for (int index = 0; index < sizeof(Random); index++) {
char digest[20];
sha.Hash(&Random[0], sizeof(Random));
sha.Result(digest);
int tocopy = sizeof(digest) < (sizeof(Random)-index) ? sizeof(digest) : (sizeof(Random)-index);
memmove(((char *)&Random[0]) + index, digest, tocopy);
}
}
/***********************************************************************************************
* RandomStraw::Get -- Fetch random data. *
* *
* This routine will fetch random data and store it into the buffer specified. *
* *
* INPUT: source -- Pointer to the buffer to fill with random data. *
* *
* length -- The number of bytes to store into the buffer. *
* *
* OUTPUT: Returns with the actual number of bytes stored into the buffer. This will always *
* be the number of bytes requested since random numbers are unexhaustible. *
* *
* WARNINGS: none *
* *
* HISTORY: *
* 07/04/1996 JLB : Created. *
* 07/10/1996 JLB : Revamped to make cryptographically secure. *
*=============================================================================================*/
int RandomStraw::Get(void * source, int slen)
{
if (source == NULL || slen < 1) {
return(Straw::Get(source, slen));
}
int total = 0;
while (slen > 0) {
*(char *)source = (char)Random[Current++];
Current = Current % (sizeof(Random) / sizeof(Random[0]));
source = (char*)source + sizeof(char);
slen--;
total++;
}
return(total);
}