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Something different: a hash which is expensive to calculate but cheap to verify. E.g. calculating a string of bytes to append to a hash stream on order to produ
by barrkel 4y ago
Something different: a hash which is expensive to calculate but cheap to verify. E.g. calculating a string of bytes to append to a hash stream on order to produce a hash with a certain number of leading zeros; you provide the hash and the bytes, and it's trivial to verify.
- zootboy 4y agoThere were proposals for this sort of thing a while back, but they never caught on: https://en.wikipedia.org/wiki/Hashcash https://en.wikipedia.org/wiki/Hashcash
- barrkel 4y agoThat's almost exactly my off the cuff suggestion. Of course my brain is seeded by both bitcoin (finding a hash as proof of work) and HLL (which counts leading hash digits to estimate set cardinality).
- amelius 4y agoNot good from an energy-wasting perspective.
- barrkel 4y agoOh I know. The point is something hard that the sender needs to do. Ideally it wouldn't waste lots of power, but it must consume some scarce resource, or else it wouldn't cost anything, and the cost should be borne by the sender, so e.g. a RAM-intensive hash function wouldn't be right.
- quickthrower2 4y agoLike cryptocurrency this will be a moving target. You would need a difficulty setting - but where as cryptocurrency only has to track one thing "total hash rate" this would need to track two things "minimum supported hardware for legit sender" and "hardware threshold for attacker to be successful with a mining rig they can afford, based on the income from the spam". Each email provider might come up with different difficulty levels based on what they thing this is. So some handshaking might be required. And less computer literate people would be stressed why their email is taking 6 minutes to send. I think it would be hard to implement.