hash.h

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT license.

#pragma once

#include <array>
#include "seal/util/common.h"
#include "seal/util/defines.h"
#include "seal/util/blake2.h"

namespace seal
{
    namespace util
    {
        class HashFunction
        {
        public:
            HashFunction() = delete;

            static constexpr std::size_t hash_block_uint64_count = 4;

            static constexpr std::size_t hash_block_byte_count =
                hash_block_uint64_count * bytes_per_uint64;

            using hash_block_type = std::array<std::uint64_t, hash_block_uint64_count>;

            static constexpr hash_block_type hash_zero_block{ { 0, 0, 0, 0 } };

            inline static void hash(const std::uint64_t *input, std::size_t uint64_count,
                hash_block_type &destination)
            {
                if (blake2b(
                    reinterpret_cast<SEAL_BYTE*>(&destination),
                    hash_block_byte_count,
                    reinterpret_cast<const SEAL_BYTE*>(input),
                    uint64_count * bytes_per_uint64,
                    nullptr, 0) != 0)
                {
                    throw std::runtime_error("blake2b failed");
                }
            }
        };
    }
}