Topic: [Theoretical]The Short-Circuit 51% attack vulnerability in non Sha256 altcoins. (Read 4171 times)

class CBlockHeader
{

    uint256 GetHash() const
    {
        return Hash9(BEGIN(nVersion), END(nNonce));
    }

};

class CBlock : public CBlockHeader
{

    uint256 GetPoWHash() const
    {
        return GetHash();
    }

};

uint256 GetPoWHash() const
    {
        return GetHash();
    }

uint256 GetBlockHash() const
    {
        CBlockHeader block;
        block.nVersion        = nVersion;
        block.hashPrevBlock   = hashPrev;
        block.hashMerkleRoot  = hashMerkleRoot;
        block.nTime           = nTime;
        block.nBits           = nBits;
        block.nNonce          = nNonce;
        return block.GetHash();
    }

uint256 GetHash() const
    {
        return SerializeHash(*this);
    }

uint256 GetHash() const
    {
        return Hash9(BEGIN(nVersion), END(nNonce));
    }

bool CheckProofOfWork(uint256 hash, unsigned int nBits)
{
    CBigNum bnTarget;
    bnTarget.SetCompact(nBits);

    // Check range
    if (bnTarget <= 0 || bnTarget > bnProofOfWorkLimit) // if Target <= 0 OR target > limit
        return error("CheckProofOfWork() : nBits below minimum work");

    // Check proof of work matches claimed amount
    if (hash > bnTarget.getuint256())  //if hash > Target 
        return error("CheckProofOfWork() : hash doesn't match nBits");


    return true;//it passed the test, it must be valid.
}

bool CheckWork(CBlock* pblock, CWallet& wallet, CReserveKey& reservekey)
{
    uint256 hash = pblock->GetPoWHash(); //get the block hash, which is obviously sha256


    uint256 hashTarget = CBigNum().SetCompact(pblock->nBits).getuint256();

    if (hash > hashTarget)
        return false;

    //// debug print
    printf("LogiCoinMiner:\n");
    printf("proof-of-work found  \n  hash: %s  \ntarget: %s\n", hash.GetHex().c_str(), hashTarget.GetHex().c_str());
    pblock->print();
    printf("generated %s\n", FormatMoney(pblock->vtx[0].vout[0].nValue).c_str());

    // Found a solution
    {
        LOCK(cs_main);
        if (pblock->hashPrevBlock != hashBestChain)
            return error("LogiCoinMiner : generated block is stale");

        // Remove key from key pool
        reservekey.KeepKey();

        // Track how many getdata requests this block gets
        {
            LOCK(wallet.cs_wallet);
            wallet.mapRequestCount[pblock->GetHash()] = 0;
        }

        // Process this block the same as if we had received it from another node
        CValidationState state;
        if (!ProcessBlock(state, NULL, pblock))
            return error("LogiCoinMiner : ProcessBlock, block not accepted");
    }

    return true;
}