osrng.h

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// osrng.h - originally written and placed in the public domain by Wei Dai
 
/// \file osrng.h
/// \brief Classes for access to the operating system's random number generators
 
#ifndef CRYPTOPP_OSRNG_H
#define CRYPTOPP_OSRNG_H
 
#include "config.h"
 
#if !defined(NO_OS_DEPENDENCE) && defined(OS_RNG_AVAILABLE)
 
#include "cryptlib.h"
#include "randpool.h"
#include "smartptr.h"
#include "fips140.h"
#include "hkdf.h"
#include "rng.h"
#include "aes.h"
#include "sha.h"
 
NAMESPACE_BEGIN(CryptoPP)
 
/// \brief Exception thrown when an operating system error is encountered
class CRYPTOPP_DLL OS_RNG_Err : public Exception
{
public:
    /// \brief Constructs an OS_RNG_Err
    /// \param operation the operation or API call when the error occurs
    OS_RNG_Err(const std::string &operation);
};
 
#ifdef NONBLOCKING_RNG_AVAILABLE
 
#ifdef CRYPTOPP_WIN32_AVAILABLE
/// \brief Wrapper for Microsoft crypto service provider
/// \sa \def USE_MS_CRYPTOAPI, \def USE_MS_CNGAPI
class CRYPTOPP_DLL MicrosoftCryptoProvider
{
public:
    /// \brief Construct a MicrosoftCryptoProvider
    MicrosoftCryptoProvider();
    ~MicrosoftCryptoProvider();
 
// type HCRYPTPROV and BCRYPT_ALG_HANDLE, avoid #include <windows.h>
#if defined(USE_MS_CRYPTOAPI)
# if defined(__CYGWIN__) && defined(__x86_64__)
    typedef unsigned long long ProviderHandle;
# elif defined(WIN64) || defined(_WIN64)
    typedef unsigned __int64 ProviderHandle;
# else
    typedef unsigned long ProviderHandle;
# endif
#elif defined(USE_MS_CNGAPI)
    typedef void *PVOID;
    typedef PVOID ProviderHandle;
#endif // USE_MS_CRYPTOAPI or USE_MS_CNGAPI
 
    /// \brief Retrieves the provider handle
    /// \return CryptoAPI provider handle
    /// \details If USE_MS_CRYPTOAPI is in effect, then CryptAcquireContext()
    ///  acquires then handle and CryptReleaseContext() releases the handle
    ///  upon destruction. If USE_MS_CNGAPI is in effect, then
    ///  BCryptOpenAlgorithmProvider() acquires then handle and
    ///  BCryptCloseAlgorithmProvider() releases the handle upon destruction.
    ProviderHandle GetProviderHandle() const {return m_hProvider;}
 
private:
    ProviderHandle m_hProvider;
};
 
#if defined(_MSC_VER) && defined(USE_MS_CRYPTOAPI)
# pragma comment(lib, "advapi32.lib")
#endif
 
#if defined(_MSC_VER) && defined(USE_MS_CNGAPI)
# pragma comment(lib, "bcrypt.lib")
#endif
 
#endif // CRYPTOPP_WIN32_AVAILABLE
 
/// \brief Wrapper class for /dev/random and /dev/srandom
/// \details Encapsulates CryptoAPI's CryptGenRandom() or CryptoNG's BCryptGenRandom()
///  on Windows, or /dev/urandom on Unix and compatibles.
class CRYPTOPP_DLL NonblockingRng : public RandomNumberGenerator
{
public:
    CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() { return "NonblockingRng"; }
 
    ~NonblockingRng();
 
    /// \brief Construct a NonblockingRng
    NonblockingRng();
 
    /// \brief Generate random array of bytes
    /// \param output the byte buffer
    /// \param size the length of the buffer, in bytes
    /// \details GenerateIntoBufferedTransformation() calls are routed to GenerateBlock().
    void GenerateBlock(byte *output, size_t size);
 
protected:
#ifdef CRYPTOPP_WIN32_AVAILABLE
    MicrosoftCryptoProvider m_Provider;
#else
    int m_fd;
#endif
};
 
#endif
 
#if defined(BLOCKING_RNG_AVAILABLE) || defined(CRYPTOPP_DOXYGEN_PROCESSING)
 
/// \brief Wrapper class for /dev/random and /dev/srandom
/// \details Encapsulates /dev/random on Linux, OS X and Unix; and /dev/srandom on the BSDs.
/// \note On Linux the /dev/random interface is effectively deprecated. According to the
///  Kernel Crypto developers, /dev/urandom or getrandom(2) should be used instead. Also
///  see <A HREF="https://lkml.org/lkml/2017/7/20/993">[RFC PATCH v12 3/4] Linux Random
///  Number Generator</A> on the kernel-crypto mailing list.
class CRYPTOPP_DLL BlockingRng : public RandomNumberGenerator
{
public:
    CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() { return "BlockingRng"; }
 
    ~BlockingRng();
 
    /// \brief Construct a BlockingRng
    BlockingRng();
 
    /// \brief Generate random array of bytes
    /// \param output the byte buffer
    /// \param size the length of the buffer, in bytes
    /// \details GenerateIntoBufferedTransformation() calls are routed to GenerateBlock().
    void GenerateBlock(byte *output, size_t size);
 
protected:
    int m_fd;
};
 
#endif
 
/// OS_GenerateRandomBlock
/// \brief Generate random array of bytes
/// \param blocking specifies whether a blocking or non-blocking generator should be used
/// \param output the byte buffer
/// \param size the length of the buffer, in bytes
/// \details OS_GenerateRandomBlock() uses the underlying operating system's
///  random number generator. On Windows, CryptGenRandom() is called using NonblockingRng.
/// \details On Unix and compatibles, /dev/urandom is called if blocking is false using
///  NonblockingRng. If blocking is true, then either /dev/randomd or /dev/srandom is used
///  by way of BlockingRng, if available.
CRYPTOPP_DLL void CRYPTOPP_API OS_GenerateRandomBlock(bool blocking, byte *output, size_t size);
 
/// \brief Automatically Seeded Randomness Pool
/// \details This class seeds itself using an operating system provided RNG.
///  AutoSeededRandomPool was suggested by Leonard Janke.
/// \details You should reseed the generator after a fork() to avoid multiple generators
///  with the same internal state.
class CRYPTOPP_DLL AutoSeededRandomPool : public RandomPool
{
public:
    CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() { return "AutoSeededRandomPool"; }
 
    ~AutoSeededRandomPool() {}
 
    /// \brief Construct an AutoSeededRandomPool
    /// \param blocking controls seeding with BlockingRng or NonblockingRng
    /// \param seedSize the size of the seed, in bytes
    /// \details 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);}
 
    /// \brief Reseed an AutoSeededRandomPool
    /// \param blocking controls seeding with BlockingRng or NonblockingRng
    /// \param seedSize the size of the seed, in bytes
    void Reseed(bool blocking = false, unsigned int seedSize = 32);
};
 
/// \tparam BLOCK_CIPHER a block cipher
/// \brief Automatically Seeded X9.17 RNG
/// \details AutoSeededX917RNG is from ANSI X9.17 Appendix C, seeded using an OS provided RNG.
///  If 3-key TripleDES (DES_EDE3) is used, then its a X9.17 conforming generator. If AES is
///  used, then its a X9.31 conforming generator.
/// \details Though ANSI X9 prescribes 3-key TripleDES, the template parameter BLOCK_CIPHER
///  can be any BlockTransformation derived class.
/// \details You should reseed the generator after a fork() to avoid multiple generators
///  with the same internal state.
/// \sa X917RNG, DefaultAutoSeededRNG
template <class BLOCK_CIPHER>
class AutoSeededX917RNG : public RandomNumberGenerator, public NotCopyable
{
public:
    static std::string StaticAlgorithmName() {
        return std::string("AutoSeededX917RNG(") + BLOCK_CIPHER::StaticAlgorithmName() + std::string(")");
    }
 
    ~AutoSeededX917RNG() {}
 
    /// \brief Construct an AutoSeededX917RNG
    /// \param blocking controls seeding with BlockingRng or NonblockingRng
    /// \param autoSeed controls auto seeding of the generator
    /// \details Use blocking to choose seeding with BlockingRng or NonblockingRng.
    ///  The parameter is ignored if only one of these is available.
    /// \sa X917RNG
    explicit AutoSeededX917RNG(bool blocking = false, bool autoSeed = true)
        {if (autoSeed) Reseed(blocking);}
 
    /// \brief Reseed an AutoSeededX917RNG
    /// \param blocking controls seeding with BlockingRng or NonblockingRng
    /// \param input additional entropy to add to the generator
    /// \param length the size of the additional entropy, in bytes
    /// \details Internally, the generator uses SHA256 to extract the entropy from
    ///  from the seed and then stretch the material for the block cipher's key
    ///  and initialization vector.
    void Reseed(bool blocking = false, const byte *input = NULLPTR, size_t length = 0);
 
    /// \brief Deterministically reseed an AutoSeededX917RNG for testing
    /// \param key the key to use for the deterministic reseeding
    /// \param keylength the size of the key, in bytes
    /// \param seed the seed to use for the deterministic reseeding
    /// \param timeVector a time vector to use for deterministic reseeding
    /// \details This is a testing interface for testing purposes, and should \a NOT
    ///  be used in production.
    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);}
 
    std::string AlgorithmProvider() const;
 
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)
{
    enum {BlockSize=BLOCK_CIPHER::BLOCKSIZE};
    enum {KeyLength=BLOCK_CIPHER::DEFAULT_KEYLENGTH};
    enum {SeedSize=EnumToInt(BlockSize)+EnumToInt(KeyLength)};
 
    SecByteBlock seed(SeedSize), temp(SeedSize);
    const byte label[] = "X9.17 key generation";
    const byte *key=NULLPTR;
 
    do
    {
        OS_GenerateRandomBlock(blocking, temp, temp.size());
 
        HKDF<SHA256> hkdf;
        hkdf.DeriveKey(
            seed, seed.size(),  // derived secret
            temp, temp.size(),  // instance secret
            input, length,      // user secret
            label, 20           // unique label
        );
 
        key = seed + BlockSize;
    }   // check that seed and key don't have same value
    while (memcmp(key, seed, STDMIN((size_t)BlockSize, (size_t)KeyLength)) == 0);
 
    Reseed(key, KeyLength, seed, NULLPTR);
}
 
template <class BLOCK_CIPHER>
std::string AutoSeededX917RNG<BLOCK_CIPHER>::AlgorithmProvider() const
{
    // Hack for now... We need to instantiate one
    typename BLOCK_CIPHER::Encryption bc;
    return bc.AlgorithmProvider();
}
 
CRYPTOPP_DLL_TEMPLATE_CLASS AutoSeededX917RNG<AES>;
 
#if defined(CRYPTOPP_DOXYGEN_PROCESSING)
/// \brief A typedef providing a default generator
/// \details DefaultAutoSeededRNG is a typedef of either AutoSeededX917RNG<AES> or AutoSeededRandomPool.
///  If CRYPTOPP_ENABLE_COMPLIANCE_WITH_FIPS_140_2 is defined, then DefaultAutoSeededRNG is
///  AutoSeededX917RNG<AES>. Otherwise, DefaultAutoSeededRNG is AutoSeededRandomPool.
/// \details You should reseed the generator after a fork() to avoid multiple generators
///  with the same internal state.
class DefaultAutoSeededRNG {}
#else
// AutoSeededX917RNG<AES> in FIPS mode, otherwise it's AutoSeededRandomPool
#if CRYPTOPP_ENABLE_COMPLIANCE_WITH_FIPS_140_2
typedef AutoSeededX917RNG<AES> DefaultAutoSeededRNG;
#else
typedef AutoSeededRandomPool DefaultAutoSeededRNG;
#endif
#endif // CRYPTOPP_DOXYGEN_PROCESSING
 
NAMESPACE_END
 
#endif
 
#endif