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Questions tagged [block-validity]

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

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What is meant by "non-standard"?

In contexts outside of "mempool policy", and broader than only transactions, what do the terms non-standard and standard mean (e.g. with reference to blocks, headers and well as transactions)...
Lee's user avatar
  • 815
3 votes
1 answer
178 views

Is the sum of sigops in the transaction details returned by getBlockTemplate not allowed to exceed 2000?

I invoke the getBlockTemplate interface using SegWit. The sum of weights in the returned transactions data is 3991625, and the sum of SigOps is 20037. Each time, I package all the transactions ...
youcai zhao's user avatar
1 vote
1 answer
78 views

Using Bitcoin as a trusted clock?

I'm looking for a way that a computer could get a rough estimate of the current date and time with a very high confidence level, for example in order to verify the expiry of a contract by means of a ...
Luca T. Castrillón's user avatar
0 votes
2 answers
135 views

What is the format of a Bitcoin block body?

To my understanding, the miners solve the nonce to get a valid block header based on the difficulty target. In the header, you have the Merkle root, which is generated from the transactions included ...
Edile's user avatar
  • 1
3 votes
2 answers
201 views

Are blocks containing non-standard transactions relayed through the network or not as in the case of non-standard transactions?

When a node receives a non-standard transaction (for example, it has more than one OP_return output or has some of the non-standard outputs), it will not be relayed further through the network, ...
dassd's user avatar
  • 1,099
4 votes
2 answers
588 views

Is there a well defined last block?

It's fairly well known when the last bitcoin will be mined, but is there a well defined last block? By that I mean, is there a block height H after which Bitcoin Core nodes will refuse to accept any ...
Tyler Levine's user avatar
1 vote
1 answer
51 views

Does checking for block validity involve checking for the validity of the whole blockchain?

In Ethereum Whitepaper there is a following description of Bitcoin's check for block validity: The algorithm for checking if a block is valid, expressed in this paradigm, is as follows: Check if the ...
bridgemnc's user avatar
  • 133
9 votes
3 answers
1k views

How many sigops are in the invalid block 783426?

On April 1st 2023 F2Pool mined block 00000000000000000002ec935e245f8ae70fc68cc828f05bf4cfa002668599e4 (full block) which my node failed with bad-blk-sigops. Bitcoin Core stops counting as soon as it ...
Sjors Provoost's user avatar
3 votes
1 answer
89 views

Do nodes accept non-standard output scripts in a mined block?

As I understand, transactions with non-standard output scripts won't be propagated through the network. I'm wondering if I were to mine a block with weird transactions whether it would be accepted by ...
Haim Bender's user avatar
3 votes
2 answers
352 views

Do non-Segwit nodes reject Segwit transactions with invalid signature?

As far as I can tell, non-Segwit nodes receive anyone-can-spend transactions, and thus come with no signature to validate. If a miner included a Segwit transaction to a block with invalid signature, ...
Angelo's user avatar
  • 423
2 votes
1 answer
139 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 ...
RareMonkey's user avatar
0 votes
3 answers
150 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 ...
Arjun Reddy's user avatar
3 votes
3 answers
2k 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 ...
Arjun Reddy's user avatar
2 votes
3 answers
263 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 ...
Arjun Reddy's user avatar
0 votes
3 answers
114 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 ...
Wonjae Oh's user avatar
3 votes
2 answers
617 views

Calculate/Verify the Hash of a Bitcoin Block Header

I want to calculate/verify the hash for block #722,460. Here is the JSON: "hash": "00000000000000000002b73f69e81b8b5e98dff0f2b7632fcb83c050c3b099a1", "confirmations": ...
Yuri's user avatar
  • 41
1 vote
3 answers
198 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 ...
RStevoUK's user avatar
  • 111
0 votes
3 answers
162 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 ...
pepperoni's user avatar
0 votes
1 answer
120 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% ...
Darshan V's user avatar
  • 101
4 votes
2 answers
632 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 ...
noctonura's 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 ...
Sprout Coder's user avatar
1 vote
2 answers
154 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....
Justin's user avatar
  • 11
3 votes
1 answer
272 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 ...
mczarnek's user avatar
  • 299
1 vote
1 answer
50 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.
user114141's user avatar
1 vote
1 answer
50 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 ...
Saxtheowl's user avatar
  • 2,800
-1 votes
1 answer
64 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 ...
Abhishek Choudhary's user avatar
0 votes
1 answer
139 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 ...
Renganathan Subramanian's user avatar
1 vote
1 answer
214 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, ...
Marcus's user avatar
  • 115
4 votes
1 answer
159 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 ...
Danny I-Tan Lin's user avatar
8 votes
1 answer
1k 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 ...
Murch's user avatar
  • 75.7k
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 ...
flair91023's 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 ...
Vaibhav Chopra's user avatar
0 votes
1 answer
234 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.
0xash's user avatar
  • 1
4 votes
1 answer
101 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 ...
Murch's user avatar
  • 75.7k
4 votes
2 answers
1k 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 ...
masoud2011's 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 ...
jack's user avatar
  • 31
1 vote
3 answers
628 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 ...
Bob5421's user avatar
  • 217
1 vote
2 answers
415 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?
Mikasa's user avatar
  • 21
9 votes
2 answers
3k 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 ...
fervi's user avatar
  • 113
11 votes
1 answer
783 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 ...
Rene Pickhardt's user avatar
1 vote
2 answers
127 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 ...
D-Samp's user avatar
  • 61
1 vote
1 answer
331 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 ...
MORTAL9's user avatar
  • 11
5 votes
2 answers
441 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 ...
Shazzad Kabir's user avatar
0 votes
1 answer
755 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 ...
3mrsh's user avatar
  • 65
0 votes
1 answer
835 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....
david.t_92's user avatar
4 votes
3 answers
306 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 ...
Ray's user avatar
  • 41
1 vote
1 answer
68 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 ...
peter's user avatar
  • 21
2 votes
2 answers
143 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?
DCH's user avatar
  • 77
2 votes
2 answers
344 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 ...
user32149's user avatar
  • 123
0 votes
1 answer
72 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
adi's user avatar
  • 27