16

Yes, one validation per block, but not one signature per block. To clear up confusion, there are 3 distinct technologies involved here: (1) non-interactive aggregation is the ability for a third party (who does not hold any private keys) to combine multiple signatures, each with their own message and public key, into a single signature that can be verified ...


13

It has no transactions other than the coinbase transaction. However, the transaction's coinbase output is 0 BTC. Here's the valuable piece of information that you are looking for: Coinbase outputs may be set lower than the max. value (12.5 currently), and the block will be valid (if the difficulty is lower than the target, as always) Also look at: https:/...


13

This will not work, because a block's content includes the previous block's hash which means that a valid block can only be mined after the previous block is known. The dummy transactions would not yield a reward to the miner, because the transaction fees are just going from the miner's left pocket to the miner's right pocket. The miner will only gain the ...


12

There are several questions here. 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 peers. Yes and no. Note that by miner we're talking about people who build blocks themselves - that includes solo miners, pool operators, and p2pool users. Hashers that only ...


11

You can't delete the block data themselves, but you can reset the blockchain state to a specific block by using the invalidateblock command. This command will mark a specific block and its descendants as invalid thus setting the chainstate to the block immediately before it. Note that this may not necessarily work to switch to a blockchain fork and may still ...


11

Mining is a random, progress-free process. Miners are essentially attempting to find a partial pre-image of a hash. Each new (valid) block candidate has exactly the same minuscule chance of yielding a new block. This means that finding a block for the next height is just as likely as finding a block that competes with the current chain-tip. However, finding ...


9

which, as I understand it, makes some data (until 2017?) real without verification. You understand incorrectly. Firstly, the assumevalid blocks is updated at every major release, so it is at most a couple of months out of date for the most recent release. For Bitcoin Core 0.18.0, the assumevalid block is ...


9

But why do miners consent that some other miner managed to mine a valid block before them? Any miner that is spending resources to find a new block will want to ensure that they are spending those resources in a way which gives them the highest chance of finding a valid block. Doing anything which lowers this chance is counter to their incentives, ...


8

A Hash Function maps "data of arbitrary size to fixed-size values". As an incredibly simple hash, consider a function only works on numbers and simply returns the last 3 (decimal) digits (ie., the 1s, 10s, and 100s places). Using this simple hash, 5 would hash to 005, and 123,456 would hash to 456. A Bitcoin block contains a handful of fields (...


7

Transactions don't have a timestamp. Blocks have a timestamp. The difference is important, because the block timestamp on some of the blocks changes the difficulty. Why is the maximum difference two hours? It's not particularly important to have very accurate timestamps. Timestamps have two uses: Difficulty retargeting Calculating progress of ...


7

Because Everyone can quickly use the transaction data to re-calculate the hash and check that it matches and is less than the target value. Computing the hash is not what takes time, it is altering the transactions details (e.g. the "nonce" value) until you find an arrangement that hashes to a value less than the target. On average this takes an ...


6

A transaction can go in a block if it's valid (references inputs that are already in the same or previous blocks, scripts are legal and return success, and signatures validate ok), regardless of whether any other nodes have ever seen it before or not. So if a "selfish" node associated with a particular miner receives a transaction, it's perfectly free to ...


6

Miners do not prove validity. They solve the problem of needing to decide between two potentially conflicting but otherwise valid versions of history. The rule that full nodes follows is that they accept the longest valid block chain, where valid is defined by the network's consensus rules, and long is defined as having more mining work performed. If a ...


6

But why do miners consent that some other miner managed to mine a valid block before them? Why don't they claim that some other miner's block is invalid even if it actually isn't, and buy time to mine one themselves? Is it because all non-miners will validate anyway and miners don't want to risk having a discarded chain? Yes, it's precisely because of the ...


5

How does a new user realizes which is the correct copy of the ledger to be used when initially updating(downloading) the ledger They find the highest-work valid blockchain. This is not the same thing as the most popular blockchain - if 999 nodes tell your node they're on a chain, but one node tells you about a longer chain, you will prefer the longer chain. ...


5

The Bitcoin protocol follows a Unspent Transaction Output system to track the existence and state of all Bitcoin in the system. These are known as UTXOs. All transactions that transfer Bitcoin do so by consuming one or more UTXOs, and create one or more new UTXOs. The only exception to this is the Coinbase transaction, which is limited to being the first ...


5

The difficulty target in the block header has to match the currently required difficulty. This value is derived and checked by each node individually from the timestamps and difficulty statements of previous blocks. Then, the block hash of a new block has to adhere to this given difficulty target. If either of the two requirements is not met, other nodes ...


4

Block contains "RSKBLOCK:Ý¿QzßýKÊwQP[9É: ÔyüN9ÝW³GÆ$", so I think that it is related to www.rsk.co. Probably Sidechains synchronization. EDIT: Binary hex: "52534b424c4f434b3addbf517adf8ffd4bca7751505b39c9013a0d1fd479fc4e901b39dd57b347c624" Source: https://blockchain.info/tx/9bf8853b3a823bbfa1e54017ae11a9e1f4d08a854dcce9f24e08114f2c921182?show_adv=true


4

As Nate Eldredge said, the block that you received is a Bitcoin Cash block which is invalid to Bitcoin Core. Because of this, your node banned the Bitcoin Cash node that sent you the block. However, it seems like the way that you have your node set up is that the gateway is acting as a proxy instead of passing through the connections. Thus Bitcoin Core ...


4

Whomever originates the transaction (the sender) wants their transaction completed as quickly as possible, especially if they attached a big "incentive" (fee) to it. So they will announce their transaction to many other nodes. Nothing really forces those nodes to share the transaction with all other nodes, although they are supposed to share it. But the ...


4

This isn't possible because every node in the network enforces the consensus rules. A miner is only allowed to include 1 transaction that moves coins with no previous inputs, which is the coinbase transaction. The output value of the coinbase transaction must not exceed the block reward plus any transaction fees from transactions in that block. If the ...


4

what is the incentive for the other miners to actually validate that it is correct? The incentive is to not mine a block on top of something that is invalid. If they do end up mining on top of an invalid block, then they waste effort (and thus money) on something that will never be accepted by the rest of the network. It seems that they might save time ...


4

Invalid transactions are never included in valid blocks. They can be included in a block, but that block would be rejected as invalid (and not classified as an orphan block).


4

A block consists of a header, and then a number of serialised transactions. The block header contains no script, it only contains data such as the merkle root of the transactions in the block (so the header commits to the list of transactions), nonce, version number, etc. Note that a block isn't encoded with JSON, it has its own serialisation format which ...


4

Can anyone elaborate on what it means exactly, please? It just seems like a weird phrasing for saying that the miner has complete control over which transactions are included in the blocks they mine. Does it really mean that those particular miners who mined the block can do whaterver they want with that block, like setting txs fees and putting txs? What ...


4

what happens if my transaction is in the fake block? It is also in the memory pool (mempool) of pending transactions at other nodes run by more honest people and will be included in a new and valid block in the normal way. Let’s suppose I am buying a Tesla car. Should I wait 6 blocks to be generated to be sure? But I have to wait 1 hour! Yes. There are ...


4

An attacker can forge fake block. Yes, but an invalid block would be rejected by all other participants that see it, and not relayed. Thus, such a block has little to no impact. This is great but what happens if my transaction is in the fake block? Let’s suppose i am buying a car. Should i wait 6 blocks to be generated to be sure? But I have to wait one ...


4

The hash is a result of computing two rounds of SHA256 on the block header. If you set the hash yourself, when other nodes try to verify the hash by performing the aforementioned computation, it will not (however, there is an infinitesimal chance) result in "63 zeros followed by a 1". I suggest reading about hash functions. The only reliable way to create ...


4

A fork happens. If A and B are competing for the next block, they probably share transactions. So you cannot simply append A to B. They're both valid blocks, nodes hold both of them until they hear about a new block that was built on top of either A or B. Let's say a node hears a new block C was built on top of B, that node will then disregard A because it ...


4

What prevents this is the requirement to have the hash of the previous block's header in the new block header which is then put through Proof-of-Work. The hash of the previous block's header cannot be known until it is created, making it impossible to compute the work ahead of time. The miner cannot just pick any old block header to base his new block on as ...


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