New answers tagged blockchain
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Every full node unilaterally checks each block for validity. When a block does not adhere to the consensus rules, a full node will not accept it as valid, will not consider included transactions as confirmed, and will not forward it to other nodes.
A similar incident happened for example in July when Antminer accidentally claimed a higher block reward than ...
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By definition a node's idea of the blockchain is among all valid versions of history the one with the most total proof of work.
Because chains are required to be valid, it is not possible to have a block in there that violates consensus rules. It doesn't matter what miners do; full nodes will still ignore the block entirely, as if it was never created.
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How can they list the unspent transactions and the current amount of an address which "is not in their wallet"?
Block explorer sites maintain a separate database of information which is built by continuously scanning the Bitcoin blockchain. If block explorer sites see a standard locking script in the outputs of the transactions, they scrape the addresses ...
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Disclosure: I'm a Software Engineer at BitGo.
You can find a guide for running BitGo Express in the corresponding module directory:
https://github.com/BitGo/BitGoJS/tree/master/modules/express
Please direct further questions to the BitGo support team via email to support@bitgo.com.
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What are the necessarily ecdsa values needed to recover the private key of a p2pkh address.
A key is recoverable if two signatures are created with the same R value.
When same address is reused numerous times to receive bitcoin what threat does it pose?
It leads to some loss of privacy, allowing different payments to be linked together.
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Your blockchain is corrupted. In Bitcoin Core's datadir, go to the blocks folder. Delete the file named blk0075.dat and ever blk*.dat file with a higher number. Also delete rev0075.dat and every rev*.dat file with a higher number. Start Bitcoin Core, it will need to reindex. At this point, it should begin building the block databases, and it will then ...
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There are multiple definitions of the term "double spending" at play here. First, there is the actual definition of double spending: to spend the same money multiple times. A simple example of this is the coin on a string in a vending machine. You put tie a string to a coin, when you put the coin in the machine, it thinks you paid, you get whatever you want ...
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The reason that is often stated is that you would have to re-calculate all the headers with all the hash values of the whole chain which is practically un-doable.
It's not the mere recalculation of new headers: miners currently create about 8×10^19 block candidates every second. However, at current difficulty levels, it takes about 4.8×10^22 block ...
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Is verification of blockchain computationally cheaper than recreating it?
Yes, far easier
How do you verify the blockchain integrity? Don't you also have to recalculate all the values to see whether they are valid?
No.
The miner has to find a value for parts of the block they can choose a value for, such that a hash of the block has a certain number of ...
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I believe you have the same problem reported in the link bellow:
https://askubuntu.com/a/490839
Just try to install autoconf. The autoreconf come with it:
sudo apt-get install autoconf
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There are no real rules, per se, just various optimizations.
ASICs are fast. They can burn through the entire 2^32 possible nonces for a given block in seconds, which requires miners to use the extra nonce field in the coinbase transaction to generate a new block header (since altering the coinbase transaction changes the merkle root) and try again.
This ...
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Yes, testnets are stable even though they are worthless, people volunteer with their computers, and because there are enough volunteers, it is stable.
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In addition to what @JBaczuk wrote, you may be interested to learn more about orphan blocks, which are created when two miners find a valid block within the latency period of block transmission across the network.
In practice, the amount of time passing between the finding of a valid block, and that block propagating across the network is very, very small, ...
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Assuming two miners have a (1/x) chance of finding a block over some time period, is the probability of both miners finding a block within that period simply (1/x^2)?
More generally, would n miners with equal hash rates have a (1/x^n) chance of all finding blocks within some time period of each other?
I believe these are both correct assuming the ...
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The difficulty is not constantly increasing. It is increasing in response to the hashrate going up. If the hashrate would be going down instead, the difficulty would automatically go down as well.
The goal of the difficulty adjustment algorithm is to keep the average time per block at 10 minutes.
If in response to dwindling fees and/or subsidy, mining ...
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who is a first miner that receive a transaction
Each full-node ends up sharing information with a small number of other active full-nodes. I believe there is a node discovery process primed by an initial list hardcoded into the node software. The nodes thus form a dynamic self-organising network with multiple hops between distantly connected nodes. Which ...
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Keeping block time at 10 minutes is only one of the many benefits that PoW provides. Other important ones include preventing double spending and transaction censorship. Most of the PoW alternative consensus mechanisms out there simply fail to ensure this level of security. There is an interesting conversation on the Bitcoin mailing list that dives into Proof-...
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Public key cryptography has nothing to do with 51% attacks. The only thing a miner can do with >50% hash power is double spend bitcoins for which he controls the private key or censor transactions by not including them in the blocks he creates. He cannot spend bitcoins for which he doesn't control the private keys.
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