Topic: Semi-Full Bitcoin Node. Downloading from ONLY pruned nodes. - page 2. (Read 479 times)

An malicious actor with more than 50% of the total hashrate can NOT 'print money'


Someone with 51%+ hashrate can decide which transactions to include (also means that he can refuse to include a single one).
He also can double spent his own transactions (since he decides which TX's to include).

But he can NOT steal other peoples money or create money out of nothing.




AFAIK, pruning is NOT enabled by default.

As long as there are 'enough' full nodes which share the full historical data (probably always will be), that's not a problem at all.

If a Semi-Full Bitcoin node only stored the complete UTXO, the last months worth of Blocks in full,  and the rest ONLY as block headers, how bad could it be ? You'd still have a complete record of the POW & User Balances, and the last months of data complete. (I believe the coin CryptoNite does something similar)

I know - if you don't have the whole chain, haven't verified every transaction since genesis - you cannot independently be sure that the whole chain is valid.  But is this actually a serious threat ?

A 51% attack could in theory print money - but that would need to go on for over a month (much more than a month actually at 51% only) and is easily recogniseable. I just don't see it.

Are we saying there is even the remotest chance that a block from a month ago has any txn errors ? With all the users that are currently running bitcoin having somehow _missed_ it ? So why do I need to download and verify it ?

I note that ETH is having a hard time at the moment as this is exactly what they have done, since their chain is so large.

As far as a pruned node is concerned - there is no loss in security from pruning data that they have verified themselves. Once a node is up to date, it just has to keep up, whilst pruning aggressively, and not lose any security.

Connecting to a network of these kinds of nodes absolutely does not have the _same_ security as a full blown Bitcoin node, but it's not far off. And if it meant that many more people ran semi-full nodes, I think it could be a bonus.

A user would only need to log on once a month minimum to catch up - before data was discarded. Seems squarely within the realms of possibility.

(I know you can do this already with Bitcoin - I am wondering if pruned nodes was the default install, and the majority of the nodes on the network used this, could the network  still thrive)