Questions tagged [chain-reorganization]

Questions about the client-local phenomenon when a Bitcoin client discovers a new chain longer in terms of difficulty than its current chain.

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18
votes
3answers
1k views

Countrywide Internet isolation, inevitable fork

Many countries around the world have provisions for shutting off the Internet as well as isolating itself from the Internet (where networking within borders still flourishes), any transaction ...
8
votes
2answers
855 views

Can the blockchain be outpaced by a chain of low-difficulty blocks?

Let's say someone creates a blockchain fork starting from the genesis block, when the difficulty was absurdly low compared to today; then he starts mining new blocks from there up to the current block ...
5
votes
1answer
501 views

How frequent are side-chain reorganizations of various lengths?

I'm wondering if anyone has collected statistics on how often reorganizations of side-chains with length 1 happen in comparison with lengths of 2, 3, or more. Related: What is the longest chain ...
9
votes
1answer
8k views

What was the goal of creating the feature of immature coins?

I just ran into the idea of immature coins. Can someone explain to me the idea behind immature coins and what was the purpose of it?
3
votes
1answer
679 views

Can an attacker with 51% of hash power change old blocks?

I read what an attacker with 51% of hash power can do in here and here. However, I want to know whether an attacker with 51% of hash power can change old blocks? For example, assume the attacker has ...
3
votes
2answers
249 views

How do I know I can trust the head of the blockchain

I'm trying to understand how the mining process works. Specifically, my understanding is the local miner works on blocks and add them to their local blockchain if they succeed. It may turn out that ...
2
votes
1answer
660 views

What is the length of largest known reorganization in bitcoin? [duplicate]

Usually there is an assumption, that a transaction is fully finalized after 6 confirmations, e.g. 6 blocks mined on top of the block, which includes given transaction. What is the length of largest ...
6
votes
2answers
1k views

51% attack and rewriting to the latest checkpoint

This is not a question about the consequence of a 51% on the price nor as to the motivation of the attacker. Let say we don't care that it's not realistic and we don't care that the attacker wouldn't ...
2
votes
2answers
101 views

Can there be stale blocks in "header first" implementation?

The Bitcoin developer guide mentions stale blocks as not being in the longest chain, then moves on to orphan blocks. It states you don't get orphan blocks, "and if you do" they are just dropped. But ...
7
votes
2answers
593 views

How does the BTC protocol guarantee that a "main" blockchain emerges?

I'm reading up on the bitcoin/blockchain technology. Usually, the part about proof of work and how to create a block is well explained. However, what is never explained is how/why the communication of ...
4
votes
1answer
210 views

How often does temporary fork occur and how long does it last?

I was wondering, how often does temporary forks occur? They appear when there are two different blocks mined based on the same previous block (parent block), but what are chances for that? And if fork ...
3
votes
1answer
150 views

When an attacker publishes a longer chain, does Bitcoin Core emit a warning?

I tried answering a question about a majority-attacker's power to change the blockchain yesterday. There is one thing I haven't been able to get a clear picture on, yet: When a previously unknown ...
3
votes
3answers
857 views

Why you need to rehash each block after a changed block when changing data in a blockchain?

Maybe my question is stupid, but, why you need to rehash each block after a changed block when changing data in a blockchain? Each block contains a hash of its data and hash of previous block. If I ...
1
vote
2answers
1k views

If a block chain is considered invalid, how about transactions in this block chain?

Say if at current time there exist split of block chain, we call them A and B. A is "longer" then B, as the result B will be eventually forgotten, but what happened about the transactions in blocks on ...
0
votes
1answer
77 views

Bitcoin fork resolution - Fork losers download previous blocks 'til common block?

When resolving a naturally occurring fork in Bitcoin, do the miners who were working on the orphaned fork download previous blocks from the miner who won the block reward that resolved the fork until ...