Re: GNUnet PoWs hashfunction

[Christian Grothoff]

On 4/18/20 1:58 PM, Bernd Fix wrote:
> On 4/18/20 11:24 AM, Jeff Burdges wrote:
>> As an aside, there is a verifiable delay function (VDF) project by
>> the ethereum foundation, which protect against parallelism.  I’d
>> expect VDFs provide less protection against ASICs per se than Argon2,
>> but they should ideally provide relatively high confidence in ASIC
>> speed.  VDFs should only consume one core while running, which might
>> improve user experience.  We can chat about this once some VDF
>> achieves the desired confidence in ASIC speed.  ;)
> 
> Actually something like VDF would be much better than a PoW in the
> context of revocation. I was trying to find something along the same
> lines (PoET, proof-of-elapsed-time) but to no avail.

I disagree that a VDF would be useful here. We want the PoW to be
_costly_. With a VDF, I could generate 1 billion keys, then wait for a
decade of delay, and then flood the network repeatedly to DoS it. Bad.
Similarly, I could NOT deploy a key, find out I urgently need to revoke
it and then just put in the resources make that happen. I may have to
wait a year!

So VDF is the _wrong_ primitive here.

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