Questions tagged [block-validity]

Collects questions regarding the validity of blocks according to consensus rules.

Filter by
Sorted by
Tagged with
2 votes
1 answer
82 views

What prevents miners from removing transactions when validating a node? [duplicate]

Simple question: when a miners receives a block of transactions, he can't add fraudulent transactions because they need to be appropriately signed, but what prevents him from erasing a tx? If he ...
user avatar
0 votes
3 answers
73 views

How does Bitcoin prevent double-spending without penalizing miners?

In the network nodes below as shown in picture: Let's say A is trying to double spend by sending bitcoins to B,C (A->B) and (A->C) and let's say A tried to relay (A->B) transaction to honest ...
user avatar
3 votes
3 answers
1k views

How is a block accepted with one invalid transaction among many valid transactions?

When a block is mined, let's say there is only one single invalid transaction out of lets say 2000 transactions in a block. Will they get rid of that one transaction and accept that remaining block or ...
user avatar
0 votes
3 answers
160 views

Can miners double-spend with two transactions in one block?

Let's say Alice sends 5 BTC to Bob and Alice tries to make double spending by again sending those same 5 BTC inputs to carl and lets say that Alice is also a one of the miner node. Here Alice tries ...
user avatar
0 votes
3 answers
49 views

What algorithm do miners use to validate individual transactions in a broadcasted solution before accepting it to their blockchain?

If proof of work is a consensus algorithm that guards against malicious nodes from adding faulty blocks, what actually happens when a miner successfully confirms a fraudulent block (i.e. a block that ...
user avatar
1 vote
3 answers
60 views

What happens if a transaction is duplicated across different blocks?

I'm sure I am missing something trivial here but I have a question. Let's say there are Node A and Node B. We send a transaction to both nodes. Both nodes now contain an unconfirmed transaction in ...
user avatar
  • 111
0 votes
3 answers
98 views

How much time do miners spend validation?

Before mining, miners have to validate previous block and transactions which exist in mempool. Then, they pick up some validated transactions from pool and start mining on top of validated block using ...
user avatar
0 votes
1 answer
82 views

How can 51% of nodes validate blocks while some are inactive?

Suppose a node doesn't have an internet connection. Since it would not receive the broadcast of other nodes, does the blockchain then propagate without the validation of that node? (That is, is it 51% ...
user avatar
4 votes
2 answers
610 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 ...
user avatar
  • 175
6 votes
9 answers
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 ...
user avatar
1 vote
2 answers
142 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....
user avatar
  • 11
2 votes
1 answer
225 views

What prevents miners from inserting fake transactions given SegWit?

If I'm understanding segwit correctly, miners have to verify signatures in order to include a transaction into a block that they are mining. However, miners are not required to verify signatures in ...
user avatar
  • 291
1 vote
1 answer
40 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.
user avatar
1 vote
1 answer
45 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 ...
user avatar
  • 2,391
-1 votes
1 answer
52 views

What will happen on creating a transaction with negative amount?

Bitcoin in short is a public ledger guided by consensus of its nodes. In theory, if there is no validation of transaction amount, if we were to create a transaction with negative amount, that would ...
user avatar
0 votes
1 answer
92 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 ...
user avatar
1 vote
1 answer
174 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, ...
user avatar
  • 115
4 votes
1 answer
119 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 ...
user avatar
8 votes
1 answer
904 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 ...
user avatar
  • 64.5k
5 votes
4 answers
3k 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 ...
user avatar
2 votes
3 answers
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 ...
user avatar
0 votes
1 answer
160 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.
user avatar
  • 1
4 votes
1 answer
79 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 ...
user avatar
  • 64.5k
4 votes
2 answers
959 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 ...
user avatar
3 votes
2 answers
3k 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 ...
user avatar
  • 31
1 vote
3 answers
542 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 ...
user avatar
  • 217
1 vote
2 answers
311 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?
user avatar
  • 21
7 votes
2 answers
1k 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 ...
user avatar
  • 93
11 votes
1 answer
709 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 ...
user avatar
1 vote
2 answers
112 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 ...
user avatar
  • 61
1 vote
1 answer
252 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 ...
user avatar
  • 11
5 votes
2 answers
367 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 ...
user avatar
0 votes
1 answer
534 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 ...
user avatar
  • 65
0 votes
1 answer
820 views

Why A Block have a Merkle root hash? [duplicate]

That is the question, why a block needs to have a Merkle root hash, as Iundestand, once a block is mined the hash value of this block is stored at the header of the next one so, it generates the chain....
user avatar
4 votes
3 answers
273 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 ...
user avatar
  • 41
1 vote
1 answer
58 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 ...
user avatar
  • 21
1 vote
1 answer
117 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?
user avatar
  • 57
2 votes
2 answers
277 views

Incentive for validating block

When miners find a solution to a block and broadcast it, what is the incentive for the other miners to actually validate that it is correct? It seems that they might save time by just starting to work ...
user avatar
  • 123
0 votes
1 answer
59 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
user avatar
  • 27
2 votes
1 answer
751 views

Does every miner verify blocks that are already in the Blockchain [duplicate]

Once a miner adds a block to the chain, does every other miner have to check that block to make sure that its transactions don't violate any rules? For instance, if a miner added a block with an ...
user avatar
  • 157
1 vote
4 answers
579 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 ...
user avatar
0 votes
4 answers
503 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 ...
user avatar
5 votes
3 answers
820 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 ...
user avatar
  • 51
4 votes
1 answer
533 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 ...
user avatar
4 votes
1 answer
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 ...
user avatar
  • 317
1 vote
2 answers
259 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 ...
user avatar
14 votes
2 answers
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 ...
user avatar
1 vote
2 answers
478 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 ...
user avatar
  • 11
1 vote
1 answer
71 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 ...
user avatar
2 votes
2 answers
69 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 ...
user avatar