[Bitcoin-development] Addressing rapid changes in mining power
etotheipi at gmail.com
Wed Nov 23 15:35:06 UTC 2011
I can substantiate Gavin's point quite powerfully: a couple months ago I
did a search for the "hardest" block in the network and found a *very
That block has a difficulty of **36 billion** when the network had a
difficulty of **1.5 million**, which is 24,000 times harder than the
target. If we were going by the /actual /hardest chain instead
target-based-hardest chain, /then this block produced in July would
might still represent the longest chain!/
Yes, that means that whichever miner produced this block, could've held
onto it for 2-4 months without doing anything else, and then broadcast
it to fork the blockchain from a block produced months ago. That's not
theoretical, that's real data in the blockchain and it would be a disaster.
On 11/23/2011 10:09 AM, Gavin Andresen wrote:
> On Wed, Nov 23, 2011 at 9:38 AM, Christian Decker
> <decker.christian at gmail.com> wrote:
>> At some point you might find an incredibly hard block that makes your forked
>> chain the hardest one in the network
> Seems to me that's the real problem with any "hardest block found in X
> minutes" scheme.
> If I get lucky and find a really extremely hard block then I have an
> incentive to keep it secret and build a couple more blocks on top of
> it, then announce them all at the same time.
> If the rest of the network rejects my longer chain because I didn't
> announce the extremely hard block in a timely fashion... then how
> could the network ever recover from a real network split? A network
> split/rejoin will look exactly the same.
> Bitcoin as-is doesn't have the "I got lucky and found an extremely
> hard block" problem because the difficulty TARGET is used to compute
> chain difficulty, not the actual hashes found.
> PS: I proposed a different method for dealing with large hash power
> drops for the testnet on the Forums yesterday, and am testing it
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