Re: [9fans] thoughs about venti+fossil

[Enrico Weigelt <weigelt@metux.de>]

* Wilhelm B. Kloke <wb@arb-phys.uni-dortmund.de> wrote:

> 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.

Which will increase the chance of a failure ;-O

> 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.

hmm, let's assume, the scientists will come up with (maybe
artificially constructed) collissions long before they'll
happen in practice, we could handle them specially. All we
need to do is to leave enough room in the keyspace, so we
can assign them to these special blocks, once they've been
discovered.

A simple way could simply be an additional bit, which tells
us that the key isn't the data's hash, but an explicitly
assigned dictionary entry.

Maybe a more sophisticated approach: add an keytype prefix,
which allows dropping in several types of keys. Default might
be sha-1, but for special cases another keytype (eg. "dict")
can be used.


cu
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