Hashpool is interesting for different reasons but what's incredibly cool is the ability to audit the pool's liabilities – unlike with any other Bitcoin mining pool.
Assets are easy to verify: the block reward. But how to check if the pool isn't skimming some sats off the top?
This problem is called proof of liabilities (POL). Since Hashpool issues mining rewards (or hash rate futures) as ecash, we can use Cashu's POL to verify that the pool operates honestly.
The challenge with POLs is that they work best if almost every user does the check. With normal wallets it's not that easy: users often don't open their wallets for long periods of time. Some just disappear forever etc.
With Hashpool, you can pretty much guarantee that most users will be perpetually online and this will run the POL verification automatically.
Cashu's POL relies on the idea of keyset epochs, essentially simulated bank runs that force the mint to show their hand. In a wallet system, epochs are maybe rotated every month or less.
With Hashpool, you could rotate much more frequently, maybe even for every block. This makes detecting fraudulent behaviour of the mint much more likely.
Users would be able to catch a cheating pool and prove it, allowing others to make informed decisions (to shame the operator and) to look for another pool to point their hash rate to.
Very excited to see how ecash can help improve Bitcoin — usually it's the other way round.
Ecash is also used in Wabisabi coinjoins due to its privacy properties which we haven't even touched on here (also improves Hashpool).
I'm sure there's more to discover along the way!
