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// rng.h - originally written and placed in the public domain by Wei Dai
/// \file rng.h
/// \brief Miscellaneous classes for RNGs
/// \details This file contains miscellaneous classes for RNGs, including LC_RNG(),
/// X917RNG() and MaurerRandomnessTest()
/// \sa osrng.h, randpool.h
#ifndef CRYPTOPP_RNG_H
#define CRYPTOPP_RNG_H
#include "cryptlib.h"
#include "filters.h"
#include "smartptr.h"
NAMESPACE_BEGIN(CryptoPP)
/// \brief Linear Congruential Generator (LCG)
/// \details Originally propsed by William S. England.
/// \warning LC_RNG is suitable for simulations, where uniformaly distrubuted numbers are
/// required quickly. It should not be used for cryptographic purposes.
class LC_RNG : public RandomNumberGenerator
{
public:
/// \brief Construct a Linear Congruential Generator (LCG)
/// \param init_seed the initial value for the generator
LC_RNG(word32 init_seed)
: seed(init_seed) {}
void GenerateBlock(byte *output, size_t size);
word32 GetSeed() {return seed;}
private:
word32 seed;
static const word32 m;
static const word32 q;
static const word16 a;
static const word16 r;
};
/// \brief ANSI X9.17 RNG
/// \details X917RNG is from ANSI X9.17 Appendix C, and it uses a 64-bit block cipher, like TripleDES.
/// If you use a 128-bit block cipher, like AES, then you are effectively using an ANSI X9.31 generator.
/// \details You should reseed the generator after a fork() to avoid multiple generators
/// with the same internal state.
/// \sa AutoSeededX917RNG, DefaultAutoSeededRNG
class CRYPTOPP_DLL X917RNG : public RandomNumberGenerator, public NotCopyable
{
public:
/// \brief Construct a X917RNG
/// \param cipher the block cipher to use for the generator
/// \param seed a byte buffer to use as a seed
/// \param deterministicTimeVector additional entropy
/// \details <tt>cipher</tt> will be deleted by the destructor. <tt>seed</tt> must be at least
/// BlockSize() in length. <tt>deterministicTimeVector = 0</tt> means obtain time vector
/// from the system.
/// \details When constructing a X917RNG, the generator must be keyed or an access
/// violation will occur because the time vector is encrypted using the block cipher.
/// To key the generator during constructions, perform the following:
/// <pre>
/// SecByteBlock key(AES::DEFAULT_KEYLENGTH), seed(AES::BLOCKSIZE);
/// OS_GenerateRandomBlock(false, key, key.size());
/// OS_GenerateRandomBlock(false, seed, seed.size());
/// X917RNG prng(new AES::Encryption(key, AES::DEFAULT_KEYLENGTH), seed, NULLPTR);</pre>
/// \sa AutoSeededX917RNG
X917RNG(BlockTransformation *cipher, const byte *seed, const byte *deterministicTimeVector = NULLPTR);
void GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword size);
private:
member_ptr<BlockTransformation> m_cipher;
const unsigned int m_size; // S, blocksize of cipher
SecByteBlock m_datetime; // DT, buffer for enciphered timestamp
SecByteBlock m_randseed, m_lastBlock, m_deterministicTimeVector;
};
/// \brief Maurer's Universal Statistical Test for Random Bit Generators
/// \details This class implements Maurer's Universal Statistical Test for
/// Random Bit Generators. It is intended for measuring the randomness of
/// *PHYSICAL* RNGs.
/// \details For more details see Maurer's paper in Journal of Cryptology, 1992.
class MaurerRandomnessTest : public Bufferless<Sink>
{
public:
/// \brief Construct a MaurerRandomnessTest
MaurerRandomnessTest();
size_t Put2(const byte *inString, size_t length, int messageEnd, bool blocking);
/// \brief Provides the number of bytes of input is needed by the test
/// \return how many more bytes of input is needed by the test
// 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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