rdrand.h

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// rdrand.h - written and placed in public domain by Jeffrey Walton and Uri Blumenthal.
//            Copyright assigned to Crypto++ project.


#ifndef CRYPTOPP_RDRAND_H
#define CRYPTOPP_RDRAND_H

#include "cryptlib.h"

// This file (and friends) provides both RDRAND and RDSEED, but its somewhat
//   experimental. They were added at Crypto++ 5.6.3. At compile time, it
//   indirectly uses CRYPTOPP_BOOL_{X86|X32|X64} (via CRYPTOPP_CPUID_AVAILABLE)
//   to select an implementation or "throw NotImplemented". At runtime, the
//   class uses the result of CPUID to determine if RDRAND or RDSEED are
//   available. If not available, a lazy throw strategy is used. I.e., the
//   throw is deferred until GenerateBlock() is called.

// Microsoft added RDRAND in August 2012, VS2012. GCC added RDRAND in December 2010, GCC 4.6.
// Clang added RDRAND in July 2012, Clang 3.2. Intel added RDRAND in September 2011, ICC 12.1.

NAMESPACE_BEGIN(CryptoPP)

class RDRAND_Err : public Exception
{
public:
        RDRAND_Err(const std::string &operation)
                : Exception(OTHER_ERROR, "RDRAND: " + operation + " operation failed") {}
};

class RDRAND : public RandomNumberGenerator
{
public:
        std::string AlgorithmName() const {return "RDRAND";}

        RDRAND(unsigned int retries = 4) : m_retries(retries) {}

        virtual ~RDRAND() {}

        unsigned int GetRetries() const
        {
                return m_retries;
        }

        void SetRetries(unsigned int retries)
        {
                m_retries = retries;
        }

#if (CRYPTOPP_BOOL_X86 || CRYPTOPP_BOOL_X32 || CRYPTOPP_BOOL_X64)
        virtual void GenerateBlock(byte *output, size_t size);
#else
        virtual void GenerateBlock(byte *output, size_t size) {
                CRYPTOPP_UNUSED(output), CRYPTOPP_UNUSED(size);
                throw NotImplemented("RDRAND: rdrand is not available on this platform");
        }
#endif

#if (CRYPTOPP_BOOL_X86 || CRYPTOPP_BOOL_X32 || CRYPTOPP_BOOL_X64)
        virtual void DiscardBytes(size_t n);
#else
        virtual void DiscardBytes(size_t n) {
                CRYPTOPP_UNUSED(n);
                throw NotImplemented("RDRAND: rdrand is not available on this platform");
        }
#endif

        virtual void IncorporateEntropy(const byte *input, size_t length)
        {
                // Override to avoid the base class' throw.
                CRYPTOPP_UNUSED(input); CRYPTOPP_UNUSED(length);
                // CRYPTOPP_ASSERT(0); // warn in debug builds
        }

private:
        unsigned int m_retries;
};

class RDSEED_Err : public Exception
{
public:
        RDSEED_Err(const std::string &operation)
                : Exception(OTHER_ERROR, "RDSEED: " + operation + " operation failed") {}
};

class RDSEED : public RandomNumberGenerator
{
public:
        std::string AlgorithmName() const {return "RDSEED";}

        RDSEED(unsigned int retries = 64) : m_retries(retries) {}

        virtual ~RDSEED() {}

        unsigned int GetRetries() const
        {
                return m_retries;
        }

        void SetRetries(unsigned int retries)
        {
                m_retries = retries;
        }

#if (CRYPTOPP_BOOL_X86 || CRYPTOPP_BOOL_X32 || CRYPTOPP_BOOL_X64)
        virtual void GenerateBlock(byte *output, size_t size);
#else
        virtual void GenerateBlock(byte *output, size_t size) {
                CRYPTOPP_UNUSED(output), CRYPTOPP_UNUSED(size);
                throw NotImplemented("RDSEED: rdseed is not available on this platform");
        }
#endif

#if (CRYPTOPP_BOOL_X86 || CRYPTOPP_BOOL_X32 || CRYPTOPP_BOOL_X64)
        virtual void DiscardBytes(size_t n);
#else
        virtual void DiscardBytes(size_t n) {
                CRYPTOPP_UNUSED(n);
                throw NotImplemented("RDSEED: rdseed is not available on this platform");
        }
#endif

        virtual void IncorporateEntropy(const byte *input, size_t length)
        {
                // Override to avoid the base class' throw.
                CRYPTOPP_UNUSED(input); CRYPTOPP_UNUSED(length);
                // CRYPTOPP_ASSERT(0); // warn in debug builds
        }

private:
        unsigned int m_retries;
};

NAMESPACE_END

#endif // CRYPTOPP_RDRAND_H