include/cryptopp/rng.h

0001 // rng.h - originally written and placed in the public domain by Wei Dai

0002
0003 /// \file rng.h

0004 /// \brief Miscellaneous classes for RNGs

0005 /// \details This file contains miscellaneous classes for RNGs, including LC_RNG(),

0006 ///  X917RNG() and MaurerRandomnessTest()

0007 /// \sa osrng.h, randpool.h

0008
0009 #ifndef CRYPTOPP_RNG_H
0010 #define CRYPTOPP_RNG_H
0011
0012 #include "cryptlib.h"
0013 #include "filters.h"
0014 #include "smartptr.h"
0015
0016 NAMESPACE_BEGIN(CryptoPP)
0017
0018 /// \brief Linear Congruential Generator (LCG)

0019 /// \details Originally propsed by William S. England.

0020 /// \warning LC_RNG is suitable for simulations, where uniformaly distributed numbers are

0021 ///  required quickly. It should not be used for cryptographic purposes.

0022 class LC_RNG : public RandomNumberGenerator
0023 {
0024 public:
0025     /// \brief Construct a Linear Congruential Generator (LCG)

0026     /// \param init_seed the initial value for the generator

0027     LC_RNG(word32 init_seed)
0028         : seed(init_seed) {}
0029
0030     void GenerateBlock(byte *output, size_t size);
0031
0032     word32 GetSeed() {return seed;}
0033
0034 private:
0035     word32 seed;
0036
0037     static const word32 m;
0038     static const word32 q;
0039     static const word16 a;
0040     static const word16 r;
0041 };
0042
0043 /// \brief ANSI X9.17 RNG

0044 /// \details X917RNG is from ANSI X9.17 Appendix C, and it uses a 64-bit block cipher, like TripleDES.

0045 ///  If you use a 128-bit block cipher, like AES, then you are effectively using an ANSI X9.31 generator.

0046 /// \details You should reseed the generator after a fork() to avoid multiple generators

0047 ///  with the same internal state.

0048 /// \sa AutoSeededX917RNG, DefaultAutoSeededRNG

0049 class CRYPTOPP_DLL X917RNG : public RandomNumberGenerator, public NotCopyable
0050 {
0051 public:
0052     /// \brief Construct a X917RNG

0053     /// \param cipher the block cipher to use for the generator

0054     /// \param seed a byte buffer to use as a seed

0055     /// \param deterministicTimeVector additional entropy

0056     /// \details <tt>cipher</tt> will be deleted by the destructor. <tt>seed</tt> must be at least

0057     ///  BlockSize() in length. <tt>deterministicTimeVector = 0</tt> means obtain time vector

0058     ///  from the system.

0059     /// \details When constructing a X917RNG, the generator must be keyed or an access

0060     ///  violation will occur because the time vector is encrypted using the block cipher.

0061     ///  To key the generator during constructions, perform the following:

0062     /// <pre>

0063     ///  SecByteBlock key(AES::DEFAULT_KEYLENGTH), seed(AES::BLOCKSIZE);

0064     ///  OS_GenerateRandomBlock(false, key, key.size());

0065     ///  OS_GenerateRandomBlock(false, seed, seed.size());

0066     ///  X917RNG prng(new AES::Encryption(key, AES::DEFAULT_KEYLENGTH), seed, NULLPTR);</pre>

0067     /// \sa AutoSeededX917RNG

0068     X917RNG(BlockTransformation *cipher, const byte *seed, const byte *deterministicTimeVector = NULLPTR);
0069
0070     void GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword size);
0071
0072 private:
0073     member_ptr<BlockTransformation> m_cipher;
0074     const unsigned int m_size;  // S, blocksize of cipher

0075     SecByteBlock m_datetime;    // DT, buffer for enciphered timestamp

0076     SecByteBlock m_randseed, m_lastBlock, m_deterministicTimeVector;
0077 };
0078
0079 /// \brief  Maurer's Universal Statistical Test for Random Bit Generators

0080 /// \details This class implements Maurer's Universal Statistical Test for

0081 ///  Random Bit Generators. It is intended for measuring the randomness of

0082 ///  *PHYSICAL* RNGs.

0083 /// \details For more details see Maurer's paper in Journal of Cryptology, 1992.

0084 class MaurerRandomnessTest : public Bufferless<Sink>
0085 {
0086 public:
0087     /// \brief Construct a MaurerRandomnessTest

0088     MaurerRandomnessTest();
0089
0090     size_t Put2(const byte *inString, size_t length, int messageEnd, bool blocking);
0091
0092     /// \brief Provides the number of bytes of input is needed by the test

0093     /// \return how many more bytes of input is needed by the test

0094     // BytesNeeded() returns how many more bytes of input is needed by the test

0095     // GetTestValue() should not be called before BytesNeeded()==0

0096     unsigned int BytesNeeded() const {return n >= (Q+K) ? 0 : Q+K-n;}
0097
0098     // returns a number between 0.0 and 1.0, describing the quality of the

0099     // random numbers entered

0100     double GetTestValue() const;
0101
0102 private:
0103     enum {L=8, V=256, Q=2000, K=2000};
0104     double sum;
0105     unsigned int n;
0106     unsigned int tab[V];
0107 };
0108
0109 NAMESPACE_END
0110
0111 #endif