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Litecoin minergate
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Each block is verified through hashing all its data and a random nonce to find a hash that has a certain number of leading zeroes. If you even removed a single little bit of data from a block, the resulting hash would be changed. As most likely the new hash would not fulfill the difficulty requirement, the proof of work would have been destroyed.
You'd have to create a new block to take its place. Then however, you would also have to recreate all subsequent block, as the parent's hash think of it as a fingerprint is included in its children block, i. What can happen is that the database of verified transactions that Bitcoin-Qt clients store is pruned.
So far, after verifying each block, full clients keep every transaction that has ever happened locally. Instead, you could only keep the transactions in your database of which the outputs have not been spent yet. A block has two parts: Header contains all the necessary data to validate the PoW and chain of headers since the genesis block header. Additionally, each header contains an authenticating value of its payload.
SPV wallets sync very fast because they validate only headers and not the payload. If a block contains transactions whose outputs have not been spent, then nodes must store that block to prove to another bootstrapping node that the UTXO set indeed contains a certain element.
On the other hand, if all outputs generated in a block say X have been spent, than a node can discard block X and say to another bootstrapping node "all UTXO of block X have been spent, just validate header and move on". This is a conservative approach. While a bootstrapping node cannot be fooled into accepting invalid UTXOs, we also cannot prove to that node that "all UTXO of block X have been spent" without exhibiting the actual payload. Now the question may be: See this answer for details.
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Questions Tags Users Badges Unanswered. How explicitly can the blockchain be pruned? How can the blockchain be pruned? If the blockchain is tamper-proof thus cannot be changed, how can the data be removed? Please be as explicit as possible. Will old accepted blocks ever be removed? The blockchain itself cannot be pruned.
Thank you so much in advance! It is similar, but not the same. In the pruned client you would still verify all blocks, but you would not keep all data. AFAIK lightweight clients actually don't verify blocks themselves. Jus12 1 7 That's impossible without seeing the full blocks. They only maintain a chain of headers. That's what the linked answer discusses; how a node obtains blocks relevant to it. Ok, yes, I don't consider that part of the node, but part of the wallet connected to it a wallet connected to a full node also has its own UTXO set in that sense , but agree.
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