dolphin/Source/Core/Common/Random.cpp
Léo Lam fff1db9730 Common: Add Random utilities
This makes it easier to generate random numbers or fill a buffer with
random data in a cryptographically secure way.

This also replaces existing usages of RNG functions in the codebase:

* <random> is pretty hard to use correctly, and std::random_device does
  not give enough guarantees about its results (it's
  implementation-defined, non cryptographically secure and could be
  deterministic on some platforms).
  Doing things correctly is error prone and verbose.

* rand() is terrible and should not be used especially in crypto code.
2018-05-31 17:54:43 +02:00

50 lines
1.1 KiB
C++

// Copyright 2018 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
#include "Common/Random.h"
#include <mbedtls/entropy.h>
#include <mbedtls/hmac_drbg.h>
#include "Common/Assert.h"
namespace Common::Random
{
class CSPRNG final
{
public:
CSPRNG()
{
mbedtls_entropy_init(&m_entropy);
mbedtls_hmac_drbg_init(&m_context);
const int ret = mbedtls_hmac_drbg_seed(&m_context, mbedtls_md_info_from_type(MBEDTLS_MD_SHA256),
mbedtls_entropy_func, &m_entropy, nullptr, 0);
ASSERT(ret == 0);
}
~CSPRNG()
{
mbedtls_hmac_drbg_free(&m_context);
mbedtls_entropy_free(&m_entropy);
}
void Generate(void* buffer, std::size_t size)
{
const int ret = mbedtls_hmac_drbg_random(&m_context, static_cast<u8*>(buffer), size);
ASSERT(ret == 0);
}
private:
mbedtls_entropy_context m_entropy;
mbedtls_hmac_drbg_context m_context;
};
static thread_local CSPRNG s_csprng;
void Generate(void* buffer, std::size_t size)
{
s_csprng.Generate(buffer, size);
}
} // namespace Common::Random