TOFU for GnuPG

Andre Heinecke aheinecke at
Tue Nov 3 16:10:24 CET 2015

Hi Neal,

On Tuesday 03 November 2015 15:57:05 Neal H. Walfield wrote:
> > I don't fully understand why you need formalized transition statements.
> > Couldn't you just treat Key / UIDs that are signed by each other as "two
> > valid keys for this UID"?
> > 
> > So when I transition to another key I just sign it with the old key and
> > GnuPG can detect that and not show a warning about it?
> > 
> > This would also solve the problem that some users may have multiple keys
> > with the same UID's which are both valid.
> This could work if both keys are available locally.  If you need to
> look up the new key, this is not so easy.

Don't we need to lookup the new key anyway to make validity decisions? Until 
then we assume "Unknown" trust.

Well I can see that one of the features of Tofu is that Unknown trust should 
no longer be presented to users but in that case we could add auto-key-
retrieve? :-)

> Another problem is that this assumes that the new key has the exact
> same user ids.  Oftentimes some emails will have been dropped or the
> person's name changed (e.g., marriage, new title, etc.).

You have lost me here. Why does it assume that? 

- I send you lots of mails as aheinecke at signed with C97822F5
- Now I send you once a mail as aheinecke at signed with 58BD45EC 

-> You can check if C97822F5 signed the User ID aheinecke at on key 
58BD45EC. It has. So you can assume the new Key is also valid for that UID.

Any new UID's on this key will have to be treated as first contact ID's. If the 
new key has less UID's I don't see a problem at all.


Andre Heinecke |  ++49-541-335083-262  |
Intevation GmbH, Neuer Graben 17, 49074 Osnabrück | AG Osnabrück, HR B 18998
Geschäftsführer: Frank Koormann, Bernhard Reiter, Dr. Jan-Oliver Wagner
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