chacha20poly1305.h

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// Copyright (c) 2023 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#ifndef BITCOIN_CRYPTO_CHACHA20POLY1305_H
#define BITCOIN_CRYPTO_CHACHA20POLY1305_H
 
#include <crypto/chacha20.h>
#include <crypto/poly1305.h>
#include <span.h>
 
#include <cstddef>
#include <cstdint>
#include <cstdlib>
 
class AEADChaCha20Poly1305 {
    ChaCha20 m_chacha20;
 
public:
    static constexpr unsigned KEYLEN = 32;
 
    static constexpr unsigned EXPANSION = Poly1305::TAGLEN;
 
    AEADChaCha20Poly1305(Span<const std::byte> key) noexcept;
 
    void SetKey(Span<const std::byte> key) noexcept;
 
    using Nonce96 = ChaCha20::Nonce96;
 
    void Encrypt(Span<const std::byte> plain, Span<const std::byte> aad,
                 Nonce96 nonce, Span<std::byte> cipher) noexcept {
        Encrypt(plain, {}, aad, nonce, cipher);
    }
 
    void Encrypt(Span<const std::byte> plain1, Span<const std::byte> plain2,
                 Span<const std::byte> aad, Nonce96 nonce,
                 Span<std::byte> cipher) noexcept;
 
    bool Decrypt(Span<const std::byte> cipher, Span<const std::byte> aad,
                 Nonce96 nonce, Span<std::byte> plain) noexcept {
        return Decrypt(cipher, aad, nonce, plain, {});
    }
 
    bool Decrypt(Span<const std::byte> cipher, Span<const std::byte> aad,
                 Nonce96 nonce, Span<std::byte> plain1,
                 Span<std::byte> plain2) noexcept;
 
    void Keystream(Nonce96 nonce, Span<std::byte> keystream) noexcept;
};
 
class FSChaCha20Poly1305 {
private:
    AEADChaCha20Poly1305 m_aead;
 
    const uint32_t m_rekey_interval;
 
    uint32_t m_packet_counter{0};
 
    uint64_t m_rekey_counter{0};
 
    void NextPacket() noexcept;
 
public:
    static constexpr auto KEYLEN = AEADChaCha20Poly1305::KEYLEN;
 
    static constexpr auto EXPANSION = AEADChaCha20Poly1305::EXPANSION;
 
    // No copy or move to protect the secret.
    FSChaCha20Poly1305(const FSChaCha20Poly1305 &) = delete;
    FSChaCha20Poly1305(FSChaCha20Poly1305 &&) = delete;
    FSChaCha20Poly1305 &operator=(const FSChaCha20Poly1305 &) = delete;
    FSChaCha20Poly1305 &operator=(FSChaCha20Poly1305 &&) = delete;
 
    FSChaCha20Poly1305(Span<const std::byte> key,
                       uint32_t rekey_interval) noexcept
        : m_aead(key), m_rekey_interval(rekey_interval) {}
 
    void Encrypt(Span<const std::byte> plain, Span<const std::byte> aad,
                 Span<std::byte> cipher) noexcept {
        Encrypt(plain, {}, aad, cipher);
    }
 
    void Encrypt(Span<const std::byte> plain1, Span<const std::byte> plain2,
                 Span<const std::byte> aad, Span<std::byte> cipher) noexcept;
 
    bool Decrypt(Span<const std::byte> cipher, Span<const std::byte> aad,
                 Span<std::byte> plain) noexcept {
        return Decrypt(cipher, aad, plain, {});
    }
 
    bool Decrypt(Span<const std::byte> cipher, Span<const std::byte> aad,
                 Span<std::byte> plain1, Span<std::byte> plain2) noexcept;
};
 
#endif // BITCOIN_CRYPTO_CHACHA20POLY1305_H