[tahoe-dev] Tahoe-LAFS Weekly Conference report, 2012-09-25

[David-Sarah Hopwood]

On 27/09/12 17:12, David-Sarah Hopwood wrote:
> On 27/09/12 16:27, Zooko Wilcox-O'Hearn wrote:
>> Topic: proof-of-storage/proof-of-retrievability
>>
>> CiC suggested a pass-through "Chess Grandmaster" style attack of
>> storage server which doesn't hold the data but queries other servers
>> to answer challenges.
> 
> Interesting! I missed this part of the call.
> 
>> amiller suggested that perhaps not knowing the verify cap would
>> prevent a storage server from doing that.
> 
> In Rainhill we wanted that:
> a) the shares are (shallowly) self-verifiable.
> b) a file can be repaired (i.e. all shares reconstructed) knowing
>    only the verify-cap/SI.

... and k of the shares, obviously.

> I think these properties are directly in conflict with preventing the
> pass-through attack, and are more important than it.
> 
> Note that with the PoS protocol, you can probe for knowledge of
> particular shares, but you can't prevent the attacker from
> reconstructing those from k other shares. So it's really a proof
> of knowledge rather than a proof of storage.

-- 
David-Sarah Hopwood ⚥

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