Function Checksum

src/netaddress.cpp:191–208

static constexpr size_t TOTAL_LEN = ADDR_TORV3_SIZE + CHECKSUM_LEN + sizeof(VERSION);

static void Checksum(Span<const uint8_t> addr_pubkey, uint8_t (&checksum)[CHECKSUM_LEN])
{
    // TORv3 CHECKSUM = H(".onion checksum" | PUBKEY | VERSION)[:2]
    static const unsigned char prefix[] = ".onion checksum";
    static constexpr size_t prefix_len = 15;

    SHA3_256 hasher;

    hasher.Write(Span{prefix}.first(prefix_len));
    hasher.Write(addr_pubkey);
    hasher.Write(VERSION);

    uint8_t checksum_full[SHA3_256::OUTPUT_SIZE];

    hasher.Finalize(checksum_full);

    memcpy(checksum, checksum_full, sizeof(checksum));
}

}; // namespace torv3