Can bitcoin history be changed?

Question

It is known that historical database of all bitcoin transactions stored in blk*.dat files. Is it possible for bitcoin-core to change any of this files in any time? Or this database is equal for all bitcoin peers (may be except the last few files)?

I think this files consist non-changable historical data for blockchain. Is it true?

score 2 · Accepted Answer · answered Aug 30 '17 at 13:49

2

Yes, Bitcoin Core can and will change the blk*.dat files, which, as has been told to you many times before, can be different for all nodes. Once Bitcoin Core has validated a block, it updates its chainstate database so that it knows what its current blockchain tip is. It also updates that database with the most recent UTXO set. So once this is done, the block can be thrown away as we have now recorded that we validated it. This is what pruning does; it throws away old blocks that we have already validated. Having the correct chainstate (UTXO set and blockchain tip) is all that matters.

answered Aug 30 '17 at 13:49

Ava Chow

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However, if pruning is not enabled, then AFAIK the most recent blk*.dat file is only appended to, and the older files are never changed at all. Is that correct? – Nate Eldredge Aug 30 '17 at 13:51
Yes. The files are append only. – Ava Chow Aug 30 '17 at 13:52
@NateEldredge how to enable or disable prunning? – Denis Leonov Aug 30 '17 at 14:42
@Denis: It's disabled by default; see https://bitcoin.stackexchange.com/questions/37496/how-can-i-run-bitcoind-in-pruning-mode for how to enable it. – Nate Eldredge Aug 30 '17 at 16:06
Bitcoin Core can change on-disk database. Malware? If need, I can prove it. Guys, don't be so homely. Answer to me. – Denis Leonov Jun 05 '18 at 04:16
I mean HISTORICAL DATA!!! – Denis Leonov Jun 05 '18 at 04:24
Bitcoin Core CAN change on-disk data. All that is stored in \Bitcoin\ directory! Wallet.dat there's too. Think about this! My log make clear the fog. – Denis Leonov Jun 05 '18 at 04:32
Bitcoin Core creates those files and uses them in its normal operation. Of course it can change those files! It isn't malware, its whole job is to modify those files, where do you think they come from? – Ava Chow Jun 05 '18 at 04:33
@AndrewChow those files has historical data. I want to save em and when we invest in BTC, we must know that HISTORY has no way to been modified. That what i mean! – Denis Leonov Jun 05 '18 at 04:36
You told that the history is impermanent. – Denis Leonov Jun 05 '18 at 06:20

Can bitcoin history be changed?

1 Answers1