New answers tagged block-validity
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The hash produced by a miner is not a random unique number per se. Generally, in the mining process, a miner will take transactions and construct a block, then using the block's header (which contains information as described by @minnmass), it will produce a SHA256 hash.
This hash is then compared with the target set by the network and if not less, the miner ...
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How does a blockchain verify
Blockchains do not verify anything; the network does. But blockchains can be used to verify things (in fact, that is the whole point of them).
that the hash provided (the one with the leading zeros that is supposed to be unique …) is indeed unique
Hashes are unique, by definition, in the sense that each block header has ...
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Calculating the hash given known values is trivially easy. How mining works is that you have to take transaction details and come up with a value (nonce) that will make the hash fit into a predefined range. Currently with bitcoin you need to have some value and compute a hash with 18 leading 0s to 'mine' a coin.
To compute the hash you take transaction ...
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A block is valid when:
its hash is lower than the difficulty
it only includes valid transactions
The hash is produced from the 80-byte blockheader. The resulting hash is then interpreted as a number to compare it to the difficulty target.
It is difficult to find a block whose header meets the difficulty: the Bitcoin network currently is currently about 163 ...
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@Sprout Coder The winning miner does not supply the hash to the network to be verified. He supplies the block. The first 80 bytes of a Bitcoin block are the block header. The block is not valid if the hash of the header is greater than the target hash. The miners hash the 80-byte header repeatedly, making a small change each time. When a miner finds a header ...
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It doesn't matter who/what made the hash up, as long as it works correctly for the given hashing function.
Let's say you manually packed a block together in notepad, randomly thought of a number in your head and tagged the block with the hash you just dreamed up, and let's just say you're the luckiest person in the universe and you just so happen to have ...
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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 (...
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The hash of a block is not simply a unique string; rather, it is a unique string generated using a hashing function.
A hashing function is a one-way algorithm that cannot be reversed. Due to this, in order to generate a desired output, you have no choice but to modify your desired input over and over until you find one that works.
This is the process of ...
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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 ...
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