Method IsValidSolution

src/crypto/equihash.cpp:740–785

template<unsigned int N, unsigned int K>
bool Equihash<N,K>::IsValidSolution(const eh_HashState& base_state, std::vector<unsigned char> soln)
{
    if (soln.size() != SolutionWidth) {
        LogPrint(BCLog::POW, "Invalid solution length: %d (expected %d)\n",
                 soln.size(), SolutionWidth);
        return false;
    }

    std::vector<FullStepRow<FinalFullWidth>> X;
    X.reserve(1 << K);
    unsigned char tmpHash[HashOutput];
    for (eh_index i : GetIndicesFromMinimal(soln, CollisionBitLength)) {
        GenerateHash(base_state, i/IndicesPerHashOutput, tmpHash, HashOutput);
        X.emplace_back(tmpHash+((i % IndicesPerHashOutput) * N/8),
                       N/8, HashLength, CollisionBitLength, i);
    }

    size_t hashLen = HashLength;
    size_t lenIndices = sizeof(eh_index);
    while (X.size() > 1) {
        std::vector<FullStepRow<FinalFullWidth>> Xc;
        for (size_t i = 0; i < X.size(); i += 2) {
            if (!HasCollision(X[i], X[i+1], CollisionByteLength)) {
                LogPrint(BCLog::POW, "Invalid solution: invalid collision length between StepRows\n");
                LogPrint(BCLog::POW, "X[i]   = %s\n", X[i].GetHex(hashLen));
                LogPrint(BCLog::POW, "X[i+1] = %s\n", X[i+1].GetHex(hashLen));
                return false;
            }
            if (X[i+1].IndicesBefore(X[i], hashLen, lenIndices)) {
                LogPrint(BCLog::POW, "Invalid solution: Index tree incorrectly ordered\n");
                return false;
            }
            if (!DistinctIndices(X[i], X[i+1], hashLen, lenIndices)) {
                LogPrint(BCLog::POW, "Invalid solution: duplicate indices\n");
                return false;
            }
            Xc.emplace_back(X[i], X[i+1], hashLen, lenIndices, CollisionByteLength);
        }
        X = Xc;
        hashLen -= CollisionByteLength;
        lenIndices *= 2;
    }

    assert(X.size() == 1);
    return X[0].IsZero(hashLen);
}

// Explicit instantiations for Equihash<96,3>
template int Equihash<96,3>::InitialiseState(eh_HashState& base_state, bool btg_salt);