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Questions tagged [best-chain]

Discusses the rules by which one chain-tip gets chosen over another, including questions about heaviest/longest chains. Closely related to [chainwork], [chain-reorganization] and [blockchain-fork].

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41 views

Given that you have the necessary computing power, how does a tampered blockchain get accepted by the network?

I read that you can only tamper with a blockchain if you have more than 50% of the computing power in the network. So say you have 51% of the computing power, then you can create a longer blockchain ...
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1answer
30 views

Several Q's about consensus about the longest chain and when this chain be confirmed? [duplicate]

According to: How Does the Blockchain Work? Each node will adopt the longest chain as the only option. But what will happen if 2 (or more) nodes will solve the next block at the same time,and they ...
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1answer
111 views

Does the Longest Chain Always Win the Mining Award?

If the longest chain (i.e, the one that's the most difficult to produce or the most transactions) is always awarded with 12.5 coins (or whatever the current prize is), what happens if a specific node ...
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0answers
34 views

Shorter Chains in blockdata

Assuming two blocks are published at exactly the same time, a race for the next block to be added to one of them begins, which eventually one chain will eventually win. My question: will the shorter ...
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1answer
47 views

Why can't a Bitcoin fork take over?

According to this question's answers, the difficulty is entirely a result of previous info on a blockchain: How is difficulty calculated? So why can't someone simply fork an earlier state of Bitcoin'...
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1answer
177 views

Why is the longest block the one that gets accepted by all the nodes?

I'm confused about one of the core principles of Bitcoin. When various nodes are confirming transactions, why does the longest block win out? That is, why doesn't the system allow whoever confirms a ...
2
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1answer
79 views

Can a two-block-sized chain override the main chain?

After i read this: Honest generators only build onto a block (by referencing it in blocks they create) if it is the latest block in the longest valid chain. "Length" is calculated as total combined ...
2
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1answer
198 views

What prevents rewriting the history of a chain with a different difficulty? [duplicate]

It looks like the difficulty is deterministic, but only if the timestamps are trusted. What's to prevent a large miner from starting back much earlier in the chain (when difficultly was miniscule) ...
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1answer
85 views

What if some attacker forks blockchain from height 1 with a constant difficulty 1?

I've been reading Satoshi's paper recently. There's one thing I cannot think through. That is because the target will limit the block production speed to 2016 blocks per two weeks on average no ...
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0answers
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How does a bitcoin node select its “current” chain [duplicate]

Suppose a bitcoin client can build many different (maximal) chains from the blocks it has received so far. Which is it going to choose as its current chain? That decision cannot be made on the basis ...
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2answers
184 views

Tie Breaker to reduce orphaned chains?

When two different miners find the same block number at roughly the same time, the chain is forked, and there is a bit of a race to develop a longer chain, leaving the alternative orphaned. Why is ...
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1answer
49 views

Why is it important that miners mine at the end of the longest branch?

In this paper, the authors present a simplified description of mining strategies. The strategy which they call "honest strategy" is to always mine a block at the end of the currently longest branch. ...
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1answer
176 views

How does Bitcoin avoid splitting into multiple p2p networks?

So since Bitcoin is completely decentralized what stops multiple p2p networks from being formed? And what happens with the block chain when two separate P2P networks eventually reach each other? Will ...
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2answers
184 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 ...
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2answers
73 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 ...
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2answers
5k views

What does “Activating Best Chain” mean?

What does "Activating Best Chain" mean? My Bitcoin Core doesn't freeze, it just takes a while. I'm curious as to what it's doing.
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0answers
44 views

Does the electrum client decide the best chain on the basis of how much work was done, or how long the chain is?

Bitcoin Core compares blockchains based on how much work they contain, and not necessarily which one is longest. This is useful for preventing time warp attacks. This comment on HN says that the ...
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2answers
2k views

How is a blockchain split resolved?

Let's say two miners created 2 different blocks and broadcast them into the network. Now some clients see blockchain 1 and other blockchain 2 which are different from each other. I would like to ...
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1answer
505 views

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?
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2answers
257 views

In what order do new blocks get processed?

Node A receives a newest block with height h1, which it determines to be valid, and therefore stores the block on disk. A little later, it receives another block with the same height h1 but a greater ...
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1answer
61 views

What does the main_chain value returned by blockchain.info mean?

What does it mean that for bitcoin block to be on the Main Chain? What other chains are there? Is this as opposed to testnet? This is regarding the main_chain value in the blockchain.info api here: ...
9
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1answer
3k views

Strongest vs Longest chain and orphaned blocks

Satoshi writes at the bottom of page 3 of his white paper that "If two nodes broadcast different versions of the next block simultaneously, some nodes may receive one or the other first. In that case, ...
2
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1answer
112 views

Is it possible that someone forks the chain?

I'm not sure I understood everything but all the clients always keep the longest chain, ok. So, what happens if an evil person injects bad transactions in a block and successfully mine it (given the ...
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2answers
2k views

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 cant find any information what this value is about. Request: getblock ...
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2answers
658 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 ...
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2answers
117 views

Blockchain length by number of blocks or transactions?

It is my understanding that the longest blockchain is the one that should be used. Is "longest" measured by the number of blocks or the number of transactions?
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2answers
1k views

Longer fake block chain with “valid” transactions

What is preventing the bitcoin client from switching to a fake block chain that would be longer that current official chain? The faked chain would contain fictional transactions, but within the faked ...
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2answers
1k views

What happens to extinct blockchains, and transactions inside of them?

While understanding the concept of block chain and proof of work, few things are confusing me. Miners always consider the longest chain(by difficulty) and work on expanding it. Now, lets say two ...
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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 ...
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3answers
559 views

Why should a miner choose the longest blockchain if another chain has a higher expected reward?

Why did miners/pools choose the longest chain for continuing it? Because with this strategy they have the highest expected bitcoin reward. The expected bitcoin reward is (new generated bitcoin (b) + ...
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2answers
10k views

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?
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2answers
3k views

How does a client decide which is the longest block chain if there is a fork?

Is it only the block height or is it the effort that went into the forks? In other words: does this decision account for different difficulties?