Crypto++ 8.2
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darn.h
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1// darn.h - written and placed in public domain by Jeffrey Walton
2// DARN requires POWER9/ISA 3.0.
3
4// At the moment only GCC 7.0 (and above) seems to support __builtin_darn()
5// and __builtin_darn_32(). Clang 7.0 does not provide them, but it does
6// support assembly instructions. XLC is unknown, but there are no hits when
7// searching IBM's site. To cover more platforms we provide GCC inline
8// assembly like we do with RDRAND and RDSEED. Platforms that don't support
9// GCC inline assembly or the builtin will fail the compile. Also see
10// https://gcc.gnu.org/onlinedocs/gcc/Basic-PowerPC-Built-in-Functions-Available-on-ISA-3_002e0.html
11
12/// \file darn.h
13/// \brief Classes for DARN RNG
14/// \sa <A HREF="https://openpowerfoundation.org/?resource_lib=power-isa-version-3-0">Power
15/// ISA Version 3.0B</A>
16/// \since Crypto++ 8.0
17
18#ifndef CRYPTOPP_DARN_H
19#define CRYPTOPP_DARN_H
20
21#include "cryptlib.h"
22
23NAMESPACE_BEGIN(CryptoPP)
24
25/// \brief Exception thrown when a DARN generator encounters
26/// a generator related error.
27/// \since Crypto++ 8.0
28class DARN_Err : public Exception
29{
30public:
31 DARN_Err(const std::string &operation)
32 : Exception(OTHER_ERROR, "DARN: " + operation + " operation failed") {}
33};
34
35/// \brief Hardware generated random numbers using DARN instruction
36/// \details DARN() provides access to Power9's random number generator. The
37/// Crypto++ implementation provides conditioned random numbers from the
38/// generator as opposed to raw random numbers. According to Power ISA 3.0B
39/// manual, a conditioned random number has been processed by hardware to
40/// reduce bias. A raw random number is unconditioned noise source output.
41/// \details According to Power ISA 3.0B manual, the random number generator
42/// provided by the <tt>darn</tt> instruction is NIST SP800-90B and SP800-90C
43/// compliant to the extent possible given the completeness of the standards
44/// at the time the hardware is designed. The random number generator provides
45/// a minimum of 0.5 bits of entropy per bit.
46/// \par Wraps
47/// darn instruction
48/// \sa <A HREF="https://openpowerfoundation.org/?resource_lib=power-isa-version-3-0">Power
49/// ISA Version 3.0B</A>, MaurerRandomnessTest() for random bit generators
50/// \since Crypto++ 8.0
52{
53public:
54 CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() { return "DARN"; }
55
56 virtual ~DARN() {}
57
58 /// \brief Construct a DARN generator
59 /// \throws DARN_Err if the random number generator is not available
60 DARN();
61
62 /// \brief Generate random array of bytes
63 /// \param output the byte buffer
64 /// \param size the length of the buffer, in bytes
65 virtual void GenerateBlock(byte *output, size_t size);
66
67 /// \brief Generate and discard n bytes
68 /// \param n the number of bytes to generate and discard
69 /// \details the RDSEED generator discards words, not bytes. If n is
70 /// not a multiple of a machine word, then it is rounded up to
71 /// that size.
72 virtual void DiscardBytes(size_t n);
73
74 /// \brief Update RNG state with additional unpredictable values
75 /// \param input unused
76 /// \param length unused
77 /// \details The operation is a nop for this generator.
78 virtual void IncorporateEntropy(const byte *input, size_t length)
79 {
80 // Override to avoid the base class' throw.
81 CRYPTOPP_UNUSED(input); CRYPTOPP_UNUSED(length);
82 }
83
84 std::string AlgorithmProvider() const {
85 return "Power9";
86 }
87
88private:
90};
91
92NAMESPACE_END
93
94#endif // CRYPTOPP_DARN_H
Exception thrown when a DARN generator encounters a generator related error.
Definition: darn.h:29
Hardware generated random numbers using DARN instruction.
Definition: darn.h:52
DARN()
Construct a DARN generator.
Definition: darn.cpp:216
virtual void DiscardBytes(size_t n)
Generate and discard n bytes.
Definition: darn.cpp:227
std::string AlgorithmProvider() const
Retrieve the provider of this algorithm.
Definition: darn.h:84
virtual void IncorporateEntropy(const byte *input, size_t length)
Update RNG state with additional unpredictable values.
Definition: darn.h:78
virtual void GenerateBlock(byte *output, size_t size)
Generate random array of bytes.
Definition: darn.cpp:221
Base class for all exceptions thrown by the library.
Definition: cryptlib.h:159
Interface for random number generators.
Definition: cryptlib.h:1384
Secure memory block with allocator and cleanup.
Definition: secblock.h:689
Abstract base classes that provide a uniform interface to this library.
Crypto++ library namespace.