osrng.h

#ifndef CRYPTOPP_OSRNG_H
#define CRYPTOPP_OSRNG_H

#include "config.h"

#ifdef OS_RNG_AVAILABLE

#include "randpool.h"
#include "rng.h"
#include "aes.h"
#include "sha.h"
#include "fips140.h"

NAMESPACE_BEGIN(CryptoPP)

//! Exception class for Operating-System Random Number Generator.
class CRYPTOPP_DLL OS_RNG_Err : public Exception
{
public:
        OS_RNG_Err(const std::string &operation);
};

#ifdef NONBLOCKING_RNG_AVAILABLE

#ifdef CRYPTOPP_WIN32_AVAILABLE
class CRYPTOPP_DLL MicrosoftCryptoProvider
{
public:
        MicrosoftCryptoProvider();
        ~MicrosoftCryptoProvider();
#if defined(_WIN64)
        typedef unsigned __int64 ProviderHandle;        // type HCRYPTPROV, avoid #include <windows.h>
#else
        typedef unsigned long ProviderHandle;
#endif
        ProviderHandle GetProviderHandle() const {return m_hProvider;}
private:
        ProviderHandle m_hProvider;
};

#pragma comment(lib, "advapi32.lib")
#endif

//! encapsulate CryptoAPI's CryptGenRandom or /dev/urandom
class CRYPTOPP_DLL NonblockingRng : public RandomNumberGenerator
{
public:
        NonblockingRng();
        ~NonblockingRng();
        void GenerateBlock(byte *output, size_t size);

protected:
#ifdef CRYPTOPP_WIN32_AVAILABLE
#       ifndef WORKAROUND_MS_BUG_Q258000
                MicrosoftCryptoProvider m_Provider;
#       endif
#else
        int m_fd;
#endif
};

#endif

#ifdef BLOCKING_RNG_AVAILABLE

//! encapsulate /dev/random, or /dev/srandom on OpenBSD
class CRYPTOPP_DLL BlockingRng : public RandomNumberGenerator
{
public:
        BlockingRng();
        ~BlockingRng();
        void GenerateBlock(byte *output, size_t size);

protected:
        int m_fd;
};

#endif

CRYPTOPP_DLL void CRYPTOPP_API OS_GenerateRandomBlock(bool blocking, byte *output, size_t size);

//! Automaticly Seeded Randomness Pool
/*! This class seeds itself using an operating system provided RNG. */
class CRYPTOPP_DLL AutoSeededRandomPool : public RandomPool
{
public:
        //! use blocking to choose seeding with BlockingRng or NonblockingRng. the parameter is ignored if only one of these is available
        explicit AutoSeededRandomPool(bool blocking = false, unsigned int seedSize = 32)
                {Reseed(blocking, seedSize);}
        void Reseed(bool blocking = false, unsigned int seedSize = 32);
};

//! RNG from ANSI X9.17 Appendix C, seeded using an OS provided RNG
template <class BLOCK_CIPHER>
class AutoSeededX917RNG : public RandomNumberGenerator, public NotCopyable
{
public:
        //! use blocking to choose seeding with BlockingRng or NonblockingRng. the parameter is ignored if only one of these is available
        explicit AutoSeededX917RNG(bool blocking = false)
                {Reseed(blocking);}
        void Reseed(bool blocking = false, const byte *additionalEntropy = NULL, size_t length = 0);
        // exposed for testing
        void Reseed(const byte *key, size_t keylength, const byte *seed, const byte *timeVector);

        bool CanIncorporateEntropy() const {return true;}
        void IncorporateEntropy(const byte *input, size_t length) {Reseed(false, input, length);}
        void GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword length) {m_rng->GenerateIntoBufferedTransformation(target, channel, length);}

private:
        member_ptr<RandomNumberGenerator> m_rng;
};

template <class BLOCK_CIPHER>
void AutoSeededX917RNG<BLOCK_CIPHER>::Reseed(const byte *key, size_t keylength, const byte *seed, const byte *timeVector)
{
        m_rng.reset(new X917RNG(new typename BLOCK_CIPHER::Encryption(key, keylength), seed, timeVector));
}

template <class BLOCK_CIPHER>
void AutoSeededX917RNG<BLOCK_CIPHER>::Reseed(bool blocking, const byte *input, size_t length)
{
        SecByteBlock seed(BLOCK_CIPHER::BLOCKSIZE + BLOCK_CIPHER::DEFAULT_KEYLENGTH);
        const byte *key;
        do
        {
                OS_GenerateRandomBlock(blocking, seed, seed.size());
                if (length > 0)
                {
                        SHA256 hash;
                        hash.Update(seed, seed.size());
                        hash.Update(input, length);
                        hash.TruncatedFinal(seed, UnsignedMin(hash.DigestSize(), seed.size()));
                }
                key = seed + BLOCK_CIPHER::BLOCKSIZE;
        }       // check that seed and key don't have same value
        while (memcmp(key, seed, STDMIN((unsigned int)BLOCK_CIPHER::BLOCKSIZE, (unsigned int)BLOCK_CIPHER::DEFAULT_KEYLENGTH)) == 0);

        Reseed(key, BLOCK_CIPHER::DEFAULT_KEYLENGTH, seed, NULL);
}

CRYPTOPP_DLL_TEMPLATE_CLASS AutoSeededX917RNG<AES>;

#if CRYPTOPP_ENABLE_COMPLIANCE_WITH_FIPS_140_2
typedef AutoSeededX917RNG<AES> DefaultAutoSeededRNG;
#else
typedef AutoSeededRandomPool DefaultAutoSeededRNG;
#endif

NAMESPACE_END

#endif

#endif

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