Linked Questions

4 votes
3 answers

Can you get the longest chain by keeping a constant low difficulty?

I'm struggling with this question that should be easy to answer. If the truth is the longest chain, what if I redo all the work from Block 1 until I have the longest chain by keeping a constant low ...
SadPepo's user avatar
  • 81
28 votes
2 answers

What does the term "Longest chain" mean?

What does the term "Longest chain" mean, as there is only one 'right' blockchain exists? How another longer chain would make the 'right' chain invalid?'s user avatar
  • 1,852
12 votes
2 answers

What is chainwork?

If I run the RPC call getBlock on the bitcoin-qt client it gives me field called chainwork containing a hash. I can't find any information what this value is about. Request: getblock ...
Dennis Kriechel's user avatar
0 votes
2 answers

What would happen if a private fork several hundred blocks ahead tried to merge back?

Suppose mining pool has been off the main network for a long time so that they are 100 or so blocks behind, but managed to mine 200 blocks in the period (say, some combination of had 33% before, ...
Joshua's user avatar
  • 129
7 votes
1 answer

Can we measure bitcoin's accumulated work in terms of entropy (in bits) directly rather than expected number of hashes?

The Background Bitcoin tracks chain work by counting the (expected) minimum number of hashes it would take to create a chain of the same number of blocks and same difficulty steps[1]. Naturally, ...
philbw4's user avatar
  • 424
5 votes
1 answer

Was the time warp attack the only reason it was not safe to compare chains by length?

One of the weaknesses of bitcoin listed on that wiki is that it was once vulnerable to the time warp attack. This attack lets a miner with >50% of the hash power to solve many more blocks in a short ...
morsecoder's user avatar
  • 14.2k
3 votes
1 answer

Rewriting the entire blockchain: is it possible to spoof block timestamps of a privately mined chain?

According to and Pieter's bitcoin.sipa, it would currently take ~200 days for an attacker with 100% of the current hashpower to rewrite the entire btc blockchain. My question pertains to how ...
chytrik's user avatar
  • 18.3k
3 votes
1 answer

Can a shorter chain overcome a longer one?

Could a dominating chain fork actually be shorter (in blocks) than its abandoned predecessor? Under what circumstances could this happen?
Doug Peters's user avatar
  • 1,366
2 votes
1 answer

What's the logic behind the way block proofs (in GetBlockProof) is calculated?

Bitcoin Core uses GetBlockProof() function to determine the contribution of a block to the total difficulty of the current chain, aka, nChainWork in CBlockIndex. I'm having trouble understanding the ...
The Quantum Physicist's user avatar
0 votes
1 answer

do isolated blocks create forks in block chain? (with forks I mean branches that are no longer valid) If yes then how does the node redeem itself? [duplicate]

I'm a newbie to cryto and wanted understand this. what happens to the chain when the isolated block is formed (in case of a double spend) ? Since chains only add blocks that come from the longest ...
Kid101's user avatar
  • 101
1 vote
0 answers

How does the bitcoin network remove duplicate blocks being generated by multiple miners?

Say there are two minersA&B and each of them have produced the next block almost at the same instant. In this situation how is the network going to decide which one is the main block and abandon ...
Mainak Sikdar's user avatar
0 votes
0 answers

What’s prevents people from appending useless blocks to very old blocks in order to revert new transactions? [duplicate]

As far as my understanding goes, nodes in the network should accept the longest branch of blocks and disregard any other branches (excuse my terminology if it’s not what’s normally used - I hope it is ...
timgfx's user avatar
  • 193