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rippled/include/xrpl/basics/hardened_hash.h
2025-07-10 18:15:42 +00:00

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C++

//------------------------------------------------------------------------------
/*
This file is part of rippled: https://github.com/ripple/rippled
Copyright (c) 2014 Ripple Labs Inc.
Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL , DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
#ifndef RIPPLE_BASICS_HARDENED_HASH_H_INCLUDED
#define RIPPLE_BASICS_HARDENED_HASH_H_INCLUDED
#include <xrpl/beast/hash/hash_append.h>
#include <xrpl/beast/hash/xxhasher.h>
#include <cstdint>
#include <mutex>
#include <random>
#include <utility>
namespace ripple {
namespace detail {
using seed_pair = std::pair<std::uint64_t, std::uint64_t>;
template <bool = true>
seed_pair
make_seed_pair() noexcept
{
struct state_t
{
std::mutex mutex;
std::random_device rng;
std::mt19937_64 gen;
std::uniform_int_distribution<std::uint64_t> dist;
state_t() : gen(rng())
{
}
// state_t(state_t const&) = delete;
// state_t& operator=(state_t const&) = delete;
};
static state_t state;
std::lock_guard lock(state.mutex);
return {state.dist(state.gen), state.dist(state.gen)};
}
} // namespace detail
/**
* Seed functor once per construction
A std compatible hash adapter that resists adversarial inputs.
For this to work, T must implement in its own namespace:
@code
template <class Hasher>
void
hash_append (Hasher& h, T const& t) noexcept
{
// hash_append each base and member that should
// participate in forming the hash
using beast::hash_append;
hash_append (h, static_cast<T::base1 const&>(t));
hash_append (h, static_cast<T::base2 const&>(t));
// ...
hash_append (h, t.member1);
hash_append (h, t.member2);
// ...
}
@endcode
Do not use any version of Murmur or CityHash for the Hasher
template parameter (the hashing algorithm). For details
see https://131002.net/siphash/#at
*/
template <class HashAlgorithm = beast::xxhasher>
class hardened_hash
{
private:
detail::seed_pair m_seeds;
public:
using result_type = typename HashAlgorithm::result_type;
hardened_hash() : m_seeds(detail::make_seed_pair<>())
{
}
template <class T>
result_type
operator()(T const& t) const noexcept
{
HashAlgorithm h(m_seeds.first, m_seeds.second);
hash_append(h, t);
return static_cast<result_type>(h);
}
};
} // namespace ripple
#endif