rng.h

// rng.h - misc RNG related classes, see also osrng.h, randpool.h

#ifndef CRYPTOPP_RNG_H
#define CRYPTOPP_RNG_H

#include "cryptlib.h"
#include "filters.h"

NAMESPACE_BEGIN(CryptoPP)

//! linear congruential generator
/*! originally by William S. England, do not use for cryptographic purposes */
class LC_RNG : public RandomNumberGenerator
{
public:
        LC_RNG(word32 init_seed)
                : seed(init_seed) {}

        byte GenerateByte();

        word32 GetSeed() {return seed;}

private:
        word32 seed;

        static const word32 m;
        static const word32 q;
        static const word16 a;
        static const word16 r;
};

//! RNG derived from ANSI X9.17 Appendix C

class CRYPTOPP_DLL X917RNG : public RandomNumberGenerator, public NotCopyable
{
public:
        // cipher will be deleted by destructor, deterministicTimeVector = 0 means obtain time vector from system
        X917RNG(BlockTransformation *cipher, const byte *seed, const byte *deterministicTimeVector = 0);

        byte GenerateByte();

private:
        member_ptr<BlockTransformation> cipher;
        const int S;                    // blocksize of cipher
        SecByteBlock dtbuf;     // buffer for enciphered timestamp
        SecByteBlock randseed, randbuf, m_deterministicTimeVector;
        int randbuf_counter;    // # of unused bytes left in randbuf
};

/** This class implements Maurer's Universal Statistical Test for Random Bit Generators
    it is intended for measuring the randomness of *PHYSICAL* RNGs.
    For more details see his paper in Journal of Cryptology, 1992. */

class MaurerRandomnessTest : public Bufferless<Sink>
{
public:
        MaurerRandomnessTest();

        size_t Put2(const byte *inString, size_t length, int messageEnd, bool blocking);

        // BytesNeeded() returns how many more bytes of input is needed by the test
        // GetTestValue() should not be called before BytesNeeded()==0
        unsigned int BytesNeeded() const {return n >= (Q+K) ? 0 : Q+K-n;}

        // returns a number between 0.0 and 1.0, describing the quality of the
        // random numbers entered
        double GetTestValue() const;

private:
        enum {L=8, V=256, Q=2000, K=2000};
        double sum;
        unsigned int n;
        unsigned int tab[V];
};

NAMESPACE_END

#endif

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