Re: [9fans] thoughs about venti+fossil

["Wilhelm B. Kloke" <wb@arb-phys.uni-dortmund.de>]

andrey mirtchovski <mirtchovski@gmail.com> schrieb:
>>  Well, cracking the lottery jackpot happens quite often (if people
>>  would buy as many lotter tickets as we've got disitinct data
>>  blocks as we have in larger data storages or network traffic
>>  over several years, it would happen very regularily).
>
> i think what you fail to take into consideration is the fact, that
> even if the chance of a collision may be relatively high by your
> standards, the chance that the colliding blocks have data of any
> significance is very, very low. i.e., the algorithm for figuring out
> whether a hash collision will be important to you personally belongs
> to EXPSPACE, which, we all know, is filled with pr0n anyways.

This analysis is not entirely correct. The fact that SHA1 is a very
interesting target for a thorough search for possible collisions
makes it a lot more likely that such a collision will be found.
After this fact the colliding block is itself very interesting,
aand it is also very likely that theis block will be stored and archived
just for this reason.

In practice though, a filesystem relying on venti could just
change the block boundaries for this case or choose some other
escape from needing to store these special blocks.
--
Dipl.-Math. Wilhelm Bernhard Kloke
Institut fuer Arbeitsphysiologie an der Universitaet Dortmund
Ardeystrasse 67, D-44139 Dortmund, Tel. 0231-1084-257
PGP: http://vestein.arb-phys.uni-dortmund.de/~wb/mypublic.key