Questions tagged [block-validity]

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14
votes
2answers
3k views

Can someone explain this weird mining activity?

I can't figure why this block has 0 coinbase with 0 transactions... however still a valid block? Or it it empty? According to whalepanda this coinbase was sacrificed by unknown miner. See the block ...
12
votes
2answers
2k views

Two blocks, two transactions, same hash

Would a block containing a transaction with an identical hash as a previous transaction be considered valid? That is, if someone made a transaction for generating Bitcoins and solve two blocks with ...
10
votes
1answer
590 views

When Schnorr signatures are part of Bitcoin will it be possible validate each block with only one signature validation?

In a recent talk Pieter Wuille talked about speed up verification when using Schnorr signatures and various algorithms for verifying multiple signatures. Would it really be possible to verify one ...
8
votes
3answers
8k views

How long does block validation take?

Assume a miner receives a new block from a connected peer. Please correct me if I'm wrong: The miner validates the newly received block before using it themself and sending it to their other connected ...
7
votes
1answer
530 views

Why is there no such thing as a redirected, forged, or fake transaction?

In the past, we had numerous questions about "fake" or "forged" transactions. Such transactions could supposedly be created even without holding any bitcoins, yet would end up in the mempool or even ...
6
votes
9answers
2k views

How does a blockchain relying on PoW verify that a hash is computed using an algorithm and not made up by a human?

How does a blockchain verify that the hash provided (the one with the leading zeros that is supposed to be unique, computed using lots of processing power) is indeed unique and that it wasn't just a ...
6
votes
2answers
674 views

Does assumevalid lower the security of Bitcoin?

Bitcoin's assumption was to download the blocks and verify it in order to prevent getting fooled. But by default, the assumevalid option is enabled in the software, which, as I understand it, makes ...
5
votes
4answers
2k views

Do miners validate each other's blocks?

I understand that to mine a block, miners solve a cryptographic problem and the solution can be easily verified by other nodes on the network, appending the new block to their blockchain. But why do ...
5
votes
2answers
221 views

How are blocks verified?

I see in the bitcoin wiki there is something called "script" which compiles down to some bytecode to be run by a very very basic virtual machine. Does this mean that each block is actually just a ...
4
votes
1answer
2k views

Bitcoin Core - Go back to a specific block?

I have a full node of Bitcoin Core wallet. I would like to know if it's possible to delete data after a certain block. For example Bitcoin is currently at block 504385. There was a fork around block ...
4
votes
2answers
704 views

What happen if some blocks are added simultaneously with same previous hash

In all of the blockchain samples that I see e.g. adilmoujahid, Savjee as I checked, they added previous Hash by creating a block. Suppose that, L is the current last block in a chain. Block A and ...
4
votes
1answer
70 views

What stops miners from manipulating “target” difficulty in the block header?

I am relatively new to understanding the fundamentals of the Bitcoin network, and I couldn't find the answer to my question. I understand how mining difficulty/target is decided and calculated in the ...
4
votes
3answers
238 views

How do I know that a node provides the accurate blockchain

When I connect with a wallet to the bitcoin network, how is the balance actually retrieved? One node? Or more? I understand it is a sum of all transactions. But when I load my wallet I assume I ...
4
votes
2answers
546 views

Why is the full blockchain required, effectively forever?

I do understand that every block is validated in terms of the blocks before it by way of the previous block's hash, all the way back to the genesis block. However, could the protocol be modified such ...
4
votes
1answer
62 views

At what block height may locktimed transactions get included?

Transactions with outputs whose sequence is smaller than UINT_MAX are interpreted as locked until the timestamp or block height specified in nLockTime is reached. Specifically regarding the block ...
4
votes
3answers
629 views

Why do miners validate transactions?

It seems that if most transactions are valid, a miner could save a little time and increase its chance of mining a block by not validating. Is the reason that there are enough invalid transactions to ...
4
votes
1answer
348 views

How does Proof of Stake prevents dishonest behaviour compared to PoW?

I know that in Proof of Work (PoW) once a node has found the solution (the nonce) they announce it to the network. Then the rest of the nodes can easily verify the correctness of the block hash and ...
4
votes
1answer
208 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 ...
3
votes
2answers
239 views

What forces transactions to be visible to all miners?

How are transactions provided to the miners? And what keeps the following scenario from occurring? A valid transaction is initially reported to a "rogue" node, A, in the network. If that node is a ...
3
votes
1answer
396 views

How does the node system understand which ledger is the latest before updating their own ledger?

I have two specific questions: How does a new user realizes which is the correct copy of the ledger to be used when initially updating(downloading) the ledger, and why is it that a user cannot ...
3
votes
1answer
452 views

Is there any relation between the block version field and the one of the transaction?

I am struggling to validate my custom miner against the testnet network and I can't seem to add a block of mine to the chain. I've noticed that all the other miners are appending version 2 blocks, so ...
2
votes
3answers
1k views

Can a miner just introduce a block full of valid predetermined transactions in the blockchain and get rewarded?

My question is - let's say a miner has control over a certain number of bitcoin addresses. He creates a block containing small transactions to and fro from these accounts ahead of time in advance and ...
2
votes
2answers
1k views

Why can't miners meet the difficulty by picking a low number for the block hash?

In terms of 'proof of work' my novice understanding is that miners are tying to come up with a 64-digit hexadecimal number, "hash," that is less than or equal to the target hash. Can't miners always ...
2
votes
3answers
2k views

Why was my full node knocked off the network last night?

Any idea what happened last night that caused my full node to fail with messages like this: (full log available upon request) 2017-09-25 21:15:59 Bitcoin version v0.15.0.1 ... 2017-09-25 21:32:33 ...
2
votes
1answer
132 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 ...
2
votes
2answers
65 views

In blockchain, particular bitcoin why is difficulty not part of the Block but merkleroothash is

After some consideration I came up with two assumptions, please correct me if I am way off here. The merkleroot being part of the block information is a validation shortcut? Difficulty not being part ...
2
votes
1answer
357 views

How does a non-upgraded node read a SegWit transaction? [duplicate]

I'm trying to understand how my node would interperet a SegWit transaction if I do not upgrade. Even if I do not upgrade, I should be ...
2
votes
0answers
650 views

PoS coin is producing conflicted chain after merging with upstream developments [closed]

I'm sorry about the title, but I could not think of a more condensed way to describe this problem. I forked an older version of blackcoin a while back to make a test altcoin for fun. I have been ...
1
vote
4answers
521 views

What stops a miner from including arbitrary transactions in their block?

Suppose there is a miner who consistently cheats. That is, she will include "Alice sent me 100 bitcoins" in every block she creates. If she became the first miner to find a passable hash, then she ...
1
vote
3answers
333 views

What happens to transactions included in extinct or invalid blocks?

I have read that a block contains several transactions. An attacker can forge fake a block. The blockchain is safe because the system will choose and keep the longest chain. So the fake block will ...
1
vote
2answers
96 views

Do miners become temporary dictators of blocks they mined?

This is something I've read here: https://blockgeeks.com/guides/bitcoin-forks-guide/ "When a group of miners discovers and mine a new block, they become temporary dictators of that block" Can anyone ...
1
vote
3answers
780 views

Why does the “global lottery” prove the validity of the blockchain?

As far as I understand it currently, when winning the "lottery" (mining) you can add a block, sum of transactions, to the blockchain. This block is in the first instance verified by all network users. ...
1
vote
2answers
113 views

How do mining rewards get verified?

I understand that a miner who adds a new block can pay the reward to their address per the coinbase transaction, but who verifies that claim? Say, for example, I add a block, but instead of claiming 6....
1
vote
2answers
145 views

What happens when the last added block in a blockchain is corrupted?

What happens when the last added block in a blockchain is corrupted? Is it still possible for the block to be accepted by a majority of the miners?
1
vote
1answer
104 views

What happens to rejected transactions ( i.e double spend or invalid transactions)?

Do they get put in an orphaned block or not get put into any block at all?
1
vote
1answer
30 views

How many times a single transaction can be included into different blocks?

I would like to know is there a limit after which a miner cannot include a transaction into his block.
1
vote
1answer
41 views

Broadcasting deprecated block version

With the recent addition of Binance to the group of miners who will accept taproot, I wonder what would happen if despite a total of more than 99% of the network accepting it, a miner still doesn't ...
1
vote
1answer
216 views

How long does it take to validate a full block?

I'm interested to know how long does it take to validate a Bitcoin block on average home pc. I'm less interested in a precise number. I'm fully aware that it can be different between different ...
1
vote
1answer
52 views

What is the correct use of the term “validating”?

First, in the Bitcoin context what does validating mean? Second, is it incorrect to say something like " the average time it takes to validate a block by the network is 10 minutes." The way, I ...
1
vote
1answer
37 views

Which sender is banned in case of nvalid transactions or blocks?

When a node receives an invalid transaction or block, as far as I know, it bans the sender for 24 hours. However, I didn't exactly get which sender is banned. Is it the neighbor node that provides the ...
1
vote
1answer
64 views

Is this Merkle hash root problem existent in Bitcoin?

In the Wikipedia article about Merkle trees, I was just reading this, unable to understand where the problem lies: Second preimage attack The Merkle hash root does not indicate the tree depth, ...
1
vote
2answers
222 views

How does the protocol prevent miners from building off of a fraudulent blockchain?

Let's say someone creates a fraudulent block and finds a nonce that solves the hash puzzle. This block is broadcasted, its hash easily verified, and it's added to the blockchain. What prevents a miner ...
1
vote
2answers
451 views

Valid block on top of invalid block

I have been researching a little on the concept of blockchain for some time now. If there is any corrupted block then others won't try to build blocks on top of it. But suppose for some time if it ...
1
vote
1answer
62 views

What prevents a node from sending a different version of the blockchain?

I understand that proof of work prevents a node from creating a new version of the blockchain unless they have >50% of the hash rate, but what if the attacker is also able to intercept the victim's ...
1
vote
1answer
140 views

How does the Bitcoin network checks if the miner has changed the mining reward? [duplicate]

You know the mining reward is just a number in the code,what if a miner changed it?
0
votes
4answers
318 views

What would happen if two miners were mining two blocks with two different set of transactions?

If two miners picked from the mempool two different sets of transactions, that were not dependent on each other. Then could both miners, mine both blocks and not create a fork? So miner 1 finishes ...
0
votes
1answer
44 views

Why do other miners check block validity along with proof of work? [duplicate]

I am new to blockchains and bitcoins. So, please pardon the lack of understanding. Assume I am a miner who adds a bogus transaction (say a transfer from my account which has 0 balance to my other ...
0
votes
1answer
97 views

What is the SPV Mining Exploit?

Can anyone explain this simply? I am not finding enough explanation exactly on this type of attack. If possible, add some additional reading to your answer so that I can understand more.
0
votes
1answer
365 views

How do you get Sibling Hashed Values in a Merkle Proof?

Merkle Proofs are one of the main reasons that people attribute Bitcoin's use of Merkle Trees. But I'm struggling to understand how these work in practice. Please explain theoretically as well as ...
0
votes
1answer
51 views

How can one full node know whether other full nodes added certain block to their blockchain?

How can one full node know whether other nodes agreed a block suggestion of a miner (so it will know whether to add the block to its blockchain too)? thank you