rdrand.h

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// rdrand.h - written and placed in public domain by Jeffrey Walton and Uri Blumenthal.
 
 
#ifndef CRYPTOPP_RDRAND_H
#define CRYPTOPP_RDRAND_H
 
#include "cryptlib.h"
 
// This class file provides both RDRAND and RDSEED. They were added at
//   Crypto++ 5.6.3. At compile time, it uses CRYPTOPP_BOOL_{X86|X32|X64}
//   to select an implementation or "throw NotImplemented". At runtime the
//   constructor will throw RDRAND_Err or RDSEED_Err if a generator is
//   is not available.
// The original classes accepted a retry count. Retries were superfluous for
//   RDRAND, and RDSEED encountered a failure about 1 in 256 bytes depending
//   on the processor. Retries were removed at Crypto++ 6.0 because
//   GenerateBlock unconditionally retries and always fulfills the request.
 
// Throughput varies wildly depending on processor and manufacturer. A Core i5 or
//   Core i7 RDRAND can generate at over 200 MiB/s. It is below theroetical
//   maximum, but it takes about 5 instructions to generate, retry and store a
//   result. A low-end Celeron may perform RDRAND at about 7 MiB/s. RDSEED
//   performs at about 1/4 to 1/2 the rate of RDRAND. AMD RDRAND performed poorly
//   during testing with Athlon X4 845. The Bulldozer v4 only performed at 1 MiB/s.
 
// Microsoft added RDRAND in August 2012, VS2012; RDSEED in October 2013, VS2013.
// GCC added RDRAND in December 2010, GCC 4.6. LLVM 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:
    CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() { return "RDRAND"; }
 
    virtual ~RDRAND() {}
 
    RDRAND();
 
    virtual void GenerateBlock(byte *output, size_t size);
 
    virtual void DiscardBytes(size_t n);
 
    virtual void IncorporateEntropy(const byte *input, size_t length)
    {
        // Override to avoid the base class' throw.
        CRYPTOPP_UNUSED(input); CRYPTOPP_UNUSED(length);
    }
 
    std::string AlgorithmProvider() const {
        return "RDRAND";
    }
};
 
class RDSEED_Err : public Exception
{
public:
    RDSEED_Err(const std::string &operation)
        : Exception(OTHER_ERROR, "RDSEED: " + operation + " operation failed") {}
};
 
class RDSEED : public RandomNumberGenerator
{
public:
    CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() { return "RDSEED"; }
 
    virtual ~RDSEED() {}
 
    RDSEED();
 
    virtual void GenerateBlock(byte *output, size_t size);
 
    virtual void DiscardBytes(size_t n);
 
    virtual void IncorporateEntropy(const byte *input, size_t length)
    {
        // Override to avoid the base class' throw.
        CRYPTOPP_UNUSED(input); CRYPTOPP_UNUSED(length);
    }
 
    std::string AlgorithmProvider() const {
        return "RDSEED";
    }
};
 
NAMESPACE_END
 
#endif // CRYPTOPP_RDRAND_H