1// Copyright (c) 2020-present The Bitcoin Core developers
2// Distributed under the MIT software license, see the accompanying
3// file COPYING or http://www.opensource.org/licenses/mit-license.php.
4
5#ifndef BITCOIN_CRYPTO_SHA3_H
6#define BITCOIN_CRYPTO_SHA3_H
7
8#include <cstddef>
9#include <cstdint>
10#include <span>
11
12//! The Keccak-f[1600] transform.
13void KeccakF(uint64_t (&st)[25]);
14
15class SHA3_256
16{
17private:
18    uint64_t m_state[25] = {0};
19    unsigned char m_buffer[8];
20    unsigned m_bufsize = 0;
21    unsigned m_pos = 0;
22
23    //! Sponge rate in bits.
24    static constexpr unsigned RATE_BITS = 1088;
25
26    //! Sponge rate expressed as a multiple of the buffer size.
27    static constexpr unsigned RATE_BUFFERS = RATE_BITS / (8 * sizeof(m_buffer));
28
29    static_assert(RATE_BITS % (8 * sizeof(m_buffer)) == 0, "Rate must be a multiple of 8 bytes");
30
31public:
32    static constexpr size_t OUTPUT_SIZE = 32;
33
34    SHA3_256() = default;
35    SHA3_256& Write(std::span<const unsigned char> data);
36    SHA3_256& Finalize(std::span<unsigned char> output);
37    SHA3_256& Reset();
38};
39
40#endif // BITCOIN_CRYPTO_SHA3_H
41