88 lines
3.2 KiB
C++
88 lines
3.2 KiB
C++
// darn.h - written and placed in public domain by Jeffrey Walton
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// DARN requires POWER9/ISA 3.0.
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// At the moment only GCC 7.0 (and above) seems to support __builtin_darn()
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// and __builtin_darn_32(). Clang 7.0 does not provide them. XLC is unknown,
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// but there are no hits when searching IBM's site. To cover more platforms
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// we provide GCC inline assembly like we do with RDRAND and RDSEED.
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// Platforms that don't support GCC inline assembly or the builtin will fail
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// the compile. Also see
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// https://gcc.gnu.org/onlinedocs/gcc/Basic-PowerPC-Built-in-Functions-Available-on-ISA-3_002e0.html
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/// \file darn.h
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/// \brief Classes for DARN RNG
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/// \since Crypto++ 8.0
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#ifndef CRYPTOPP_DARN_H
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#define CRYPTOPP_DARN_H
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#include "cryptlib.h"
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NAMESPACE_BEGIN(CryptoPP)
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/// \brief Exception thrown when a DARN generator encounters
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/// a generator related error.
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/// \sa <A HREF="https://openpowerfoundation.org/?resource_lib=power-isa-version-3-0">Power
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/// ISA Version 3.0B</A>
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/// \since Crypto++ 8.0
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class DARN_Err : public Exception
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{
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public:
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DARN_Err(const std::string &operation)
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: Exception(OTHER_ERROR, "DARN: " + operation + " operation failed") {}
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};
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/// \brief Hardware generated random numbers using DARN instruction
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/// \details DARN() provides access to Power9's random number generator.
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/// \details According to Power ISA 3.0B manual, the random number generator
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/// provided by this instruction is NIST SP800-90B and SP800-90C compliant to
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/// the extent possible given the completeness of the standards at the time
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/// the hardware is designed. The random number generator provides a minimum
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/// of 0.5 bits of entropy per bit.
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/// \par Wraps
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/// darn instruction
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/// \sa <A HREF="https://openpowerfoundation.org/?resource_lib=power-isa-version-3-0">Power
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/// ISA Version 3.0B</A>, MaurerRandomnessTest() for random bit generators
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/// \since Crypto++ 8.0
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class DARN : public RandomNumberGenerator
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{
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public:
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CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() { return "DARN"; }
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virtual ~DARN() {}
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/// \brief Construct a DARN generator
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/// \throws DARN_Err if the random number generator is not available
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DARN();
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/// \brief Generate random array of bytes
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/// \param output the byte buffer
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/// \param size the length of the buffer, in bytes
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virtual void GenerateBlock(byte *output, size_t size);
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/// \brief Generate and discard n bytes
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/// \param n the number of bytes to generate and discard
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/// \details the RDSEED generator discards words, not bytes. If n is
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/// not a multiple of a machine word, then it is rounded up to
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/// that size.
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virtual void DiscardBytes(size_t n);
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/// \brief Update RNG state with additional unpredictable values
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/// \param input unused
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/// \param length unused
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/// \details The operation is a nop for this generator.
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virtual void IncorporateEntropy(const byte *input, size_t length)
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{
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// Override to avoid the base class' throw.
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CRYPTOPP_UNUSED(input); CRYPTOPP_UNUSED(length);
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}
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std::string AlgorithmProvider() const {
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return "Power9";
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}
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};
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NAMESPACE_END
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#endif // CRYPTOPP_DARN_H
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