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When miners build valid blocks with transactions, they put in significant amount of compute work to generate a hash of the block header that meets the difficulty requirement. Blockchain is a chain of blocks where each block header references the hash of the header of the previous block. The hash of the block header is calculated using all the elements of the ...


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he is inputting any arbitrary values, in order to get a value that can be hashed into something with certain preceding zeros. When he got that value, he put that value into the blockchain and generate a new block. It happens in reverse. First the miner builds the new block itself. Then builds its header, then hashes that header. Also what the miner looks ...


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SPV (lightweight) users do not have a chain. (Well, some SPV users have a fraction of the full chain, but some SPV users only have block headers. Am I correct?) SPV clients only keep track of the block headers, usually rely on other nodes to do the block validity verification, and do not keep any full blocks around. This may seem similar to a pruned node ...


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No. Block data is written (appended to) blk*.dat files whenever a block is received from the network (assuming things like PoW and a few other sanity checks pass). As blocks are received in parallel from multiple peers, their order on disk ends up being chaotic. Undo data is written when a block gets fully validated. As full validation requires validation ...


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The question at this step is: does the wallet app perform any kind of transaction validation that requires to check the whole history of the blockchain at this level ? It depends on the wallet. In general, a wallet will likely do some validation as a sanity check to ensure that the transaction they create is valid and will be accepted by nodes on the ...


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The timestamp is set by the miner and is part of the data hashed for the Proof of Work. So it is set at the time the miner begins hashing a particular header and searching for a nonce for it.


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Would you please clarify the reason behind the invention of Blocks? When determining who owns what money, the ordering of transactions becomes important. If I only have $10, and then tell both Alice and Bob that I paid $10 to them, who will rightfully own the $10? Some sort of clock/timestamp is needed, in order to determine who received the payment first, ...


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