srandom.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/>.
*/
 
#ifndef SRANDOM_H
#define SRANDOM_H
 
#include "random.h" // for the helper RNG
 
//
//  SecureRandomClass - Generate random values that are suitable for use in cryptographic
//      applications (under UNIX at least).
//
//  NOTE: The seed generation under windows isn't nearly as strong as under UNIX due to
//      the lack of /dev/random.  If you have a good random source you can call 'Add_Seeds'
//      to improve the quality of the seed value.
//
// Currently the random seed generation under windows is piss-poor so make sure and call
//      Add_Seeds with some interesting data if you're going to use this!
//
//  The seed values should be unguessable by an outside viewer and the random values have
//      good distribution properties.
//
class SecureRandomClass
{
public:
        SecureRandomClass();
        ~SecureRandomClass();
 
        unsigned long               Randval();               // get a 32 bit random value
 
                                                                    // Add randomness to the seed pool
        void                            Add_Seeds(unsigned char *values, int length);
 
private:
        void                            Generate_Seed(void);    // Generate the inital seed
 
        enum
        {
            SeedLength =            16,     // bytes in random seed
            SHADigestBytes =        20          // length of SHA hash
        };
 
        static bool                 Initialized;            // has the seed been initialized?
        static unsigned char        Seeds[SeedLength];  // random seed values
        static unsigned int     RandomCache[SHADigestBytes / sizeof(unsigned int)];
        static int                  RandomCacheEntries;
        static unsigned int     Counter;
 
        static Random3Class     RandomHelper;
};
 
#endif