siphash.cpp

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// Copyright (c) 2016-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#include <crypto/siphash.h>
 
#include <uint256.h>
 
#include <bit>
#include <cassert>
#include <span>
 
#define SIPROUND do { \
    v0 += v1; v1 = std::rotl(v1, 13); v1 ^= v0; \
    v0 = std::rotl(v0, 32); \
    v2 += v3; v3 = std::rotl(v3, 16); v3 ^= v2; \
    v0 += v3; v3 = std::rotl(v3, 21); v3 ^= v0; \
    v2 += v1; v1 = std::rotl(v1, 17); v1 ^= v2; \
    v2 = std::rotl(v2, 32); \
} while (0)
 
CSipHasher::CSipHasher(uint64_t k0, uint64_t k1)
{
    v[0] = 0x736f6d6570736575ULL ^ k0;
    v[1] = 0x646f72616e646f6dULL ^ k1;
    v[2] = 0x6c7967656e657261ULL ^ k0;
    v[3] = 0x7465646279746573ULL ^ k1;
    count = 0;
    tmp = 0;
}
 
CSipHasher& CSipHasher::Write(uint64_t data)
{
    uint64_t v0 = v[0], v1 = v[1], v2 = v[2], v3 = v[3];
 
    assert(count % 8 == 0);
 
    v3 ^= data;
    SIPROUND;
    SIPROUND;
    v0 ^= data;
 
    v[0] = v0;
    v[1] = v1;
    v[2] = v2;
    v[3] = v3;
 
    count += 8;
    return *this;
}
 
CSipHasher& CSipHasher::Write(std::span<const unsigned char> data)
{
    uint64_t v0 = v[0], v1 = v[1], v2 = v[2], v3 = v[3];
    uint64_t t = tmp;
    uint8_t c = count;
 
    while (data.size() > 0) {
        t |= uint64_t{data.front()} << (8 * (c % 8));
        c++;
        if ((c & 7) == 0) {
            v3 ^= t;
            SIPROUND;
            SIPROUND;
            v0 ^= t;
            t = 0;
        }
        data = data.subspan(1);
    }
 
    v[0] = v0;
    v[1] = v1;
    v[2] = v2;
    v[3] = v3;
    count = c;
    tmp = t;
 
    return *this;
}
 
uint64_t CSipHasher::Finalize() const
{
    uint64_t v0 = v[0], v1 = v[1], v2 = v[2], v3 = v[3];
 
    uint64_t t = tmp | (((uint64_t)count) << 56);
 
    v3 ^= t;
    SIPROUND;
    SIPROUND;
    v0 ^= t;
    v2 ^= 0xFF;
    SIPROUND;
    SIPROUND;
    SIPROUND;
    SIPROUND;
    return v0 ^ v1 ^ v2 ^ v3;
}
 
uint64_t SipHashUint256(uint64_t k0, uint64_t k1, const uint256& val)
{
    /* Specialized implementation for efficiency */
    uint64_t d = val.GetUint64(0);
 
    uint64_t v0 = 0x736f6d6570736575ULL ^ k0;
    uint64_t v1 = 0x646f72616e646f6dULL ^ k1;
    uint64_t v2 = 0x6c7967656e657261ULL ^ k0;
    uint64_t v3 = 0x7465646279746573ULL ^ k1 ^ d;
 
    SIPROUND;
    SIPROUND;
    v0 ^= d;
    d = val.GetUint64(1);
    v3 ^= d;
    SIPROUND;
    SIPROUND;
    v0 ^= d;
    d = val.GetUint64(2);
    v3 ^= d;
    SIPROUND;
    SIPROUND;
    v0 ^= d;
    d = val.GetUint64(3);
    v3 ^= d;
    SIPROUND;
    SIPROUND;
    v0 ^= d;
    v3 ^= (uint64_t{4}) << 59;
    SIPROUND;
    SIPROUND;
    v0 ^= (uint64_t{4}) << 59;
    v2 ^= 0xFF;
    SIPROUND;
    SIPROUND;
    SIPROUND;
    SIPROUND;
    return v0 ^ v1 ^ v2 ^ v3;
}
 
uint64_t SipHashUint256Extra(uint64_t k0, uint64_t k1, const uint256& val, uint32_t extra)
{
    /* Specialized implementation for efficiency */
    uint64_t d = val.GetUint64(0);
 
    uint64_t v0 = 0x736f6d6570736575ULL ^ k0;
    uint64_t v1 = 0x646f72616e646f6dULL ^ k1;
    uint64_t v2 = 0x6c7967656e657261ULL ^ k0;
    uint64_t v3 = 0x7465646279746573ULL ^ k1 ^ d;
 
    SIPROUND;
    SIPROUND;
    v0 ^= d;
    d = val.GetUint64(1);
    v3 ^= d;
    SIPROUND;
    SIPROUND;
    v0 ^= d;
    d = val.GetUint64(2);
    v3 ^= d;
    SIPROUND;
    SIPROUND;
    v0 ^= d;
    d = val.GetUint64(3);
    v3 ^= d;
    SIPROUND;
    SIPROUND;
    v0 ^= d;
    d = ((uint64_t{36}) << 56) | extra;
    v3 ^= d;
    SIPROUND;
    SIPROUND;
    v0 ^= d;
    v2 ^= 0xFF;
    SIPROUND;
    SIPROUND;
    SIPROUND;
    SIPROUND;
    return v0 ^ v1 ^ v2 ^ v3;
}