Files
rippled/src/libxrpl/crypto/csprng.cpp
2026-04-01 13:27:22 -04:00

87 lines
2.0 KiB
C++

#include <xrpl/basics/contract.h>
#include <xrpl/crypto/csprng.h>
#include <openssl/rand.h>
#include <openssl/ssl.h>
#include <array>
#include <cstddef>
#include <mutex>
#include <random>
#include <stdexcept>
namespace xrpl {
csprng_engine::csprng_engine()
{
// This is not strictly necessary
if (RAND_poll() != 1)
Throw<std::runtime_error>("CSPRNG: Initial polling failed");
}
csprng_engine::~csprng_engine()
{
// This cleanup function is not needed in newer versions of OpenSSL
#if (OPENSSL_VERSION_NUMBER < 0x10100000L)
RAND_cleanup();
#endif
}
void
csprng_engine::mix_entropy(void* buffer, std::size_t count)
{
std::array<std::random_device::result_type, 128> entropy{};
{
// On every platform we support, std::random_device
// is non-deterministic and should provide some good
// quality entropy.
std::random_device rd;
for (auto& e : entropy)
e = rd();
}
std::lock_guard const lock(mutex_);
// We add data to the pool, but we conservatively assume that
// it contributes no actual entropy.
RAND_add(entropy.data(), entropy.size() * sizeof(std::random_device::result_type), 0);
if (buffer != nullptr && count != 0)
RAND_add(buffer, count, 0);
}
void
csprng_engine::operator()(void* ptr, std::size_t count)
{
// RAND_bytes is thread-safe on OpenSSL 1.1.0 and later when compiled
// with thread support, so we don't need to grab a mutex.
// https://mta.openssl.org/pipermail/openssl-users/2020-November/013146.html
#if (OPENSSL_VERSION_NUMBER < 0x10100000L) || !defined(OPENSSL_THREADS)
std::lock_guard lock(mutex_);
#endif
auto const result = RAND_bytes(reinterpret_cast<unsigned char*>(ptr), count);
if (result != 1)
Throw<std::runtime_error>("CSPRNG: Insufficient entropy");
}
csprng_engine::result_type
csprng_engine::operator()()
{
result_type ret = 0;
(*this)(&ret, sizeof(result_type));
return ret;
}
csprng_engine&
crypto_prng()
{
static csprng_engine engine;
return engine;
}
} // namespace xrpl