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/*
* RDRAND RNG
* (C) 2016 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_RNG_RDRAND_H_
#define BOTAN_RNG_RDRAND_H_
#include <botan/rng.h>
namespace Botan {
class BOTAN_PUBLIC_API(2,0) RDRAND_RNG final : public Hardware_RNG
{
public:
/**
* On correctly working hardware, RDRAND is always supposed to
* succeed within a set number of retries. If after that many
* retries RDRAND has still not suceeded, sets ok = false and
* returns 0.
*/
static uint32_t rdrand_status(bool& ok);
/*
* Calls RDRAND until it succeeds, this could hypothetically
* loop forever on broken hardware.
*/
static uint32_t rdrand();
/**
* Constructor will throw if CPU does not have RDRAND bit set
*/
RDRAND_RNG();
/**
* Uses RDRAND to produce output
*/
void randomize(uint8_t out[], size_t out_len) override;
/*
* No way to provide entropy to RDRAND generator, so add_entropy is ignored
*/
void add_entropy(const uint8_t[], size_t) override
{ /* no op */ }
/*
* No way to reseed RDRAND generator, so reseed is ignored
*/
size_t reseed(Entropy_Sources&, size_t, std::chrono::milliseconds) override
{ return 0; /* no op */ }
std::string name() const override { return "RDRAND"; }
bool is_seeded() const override { return true; }
};
}
#endif
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