[tahoe-dev] Question about convergence keys

Brian Warner warner-tahoe at allmydata.com
Fri Aug 22 01:26:23 UTC 2008

[Sorry I didn't respond to this earlier, I was out on vacation for a bit.]

On Tue, 12 Aug 2008 21:58:40 -0700
Jeremy Fitzhardinge <jeremy at goop.org> wrote:

> So, presumably if a client changes its convergence key, does it lose access
> to all its previously stored content?

Eek, no!

> Or does it just change the capabilities generated when you store something?

Changing the convergence secret does the latter: it merely changes the caps
that get created during upload. All previously-generated caps remain valid.
Caps are 'necessary and sufficient', and if they depended upon some external
secret, they wouldn't still be 'sufficient'. Also, such a dependence would
make it impossible to share single files with other people.

> If you're using tahoe to do a full system backup, and you need to recover
> everything, what's the minimum needed to do that? Is it just the read
> capability of the root of the backup tree?

Yes, precisely.


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