About UIDs

David Shaw dshaw at jabberwocky.com
Wed Oct 15 01:39:41 CEST 2008

On Oct 14, 2008, at 6:22 PM, Faramir wrote:

> I have a question about the UID associated to the key: Are they placed
> in the public key, or in both private and public keys?
> And, if I have a key with 2 UIDs, and I sign another key (lets say, I
> sign Alice's key), will be both UIDs be displayed in the signatures,  
> or
> just the one that was my primary UID at the moment when I signed  
> Alice's
> key?

Neither.  Signatures only contain the key ID of the key making the  
signature.  When displaying signatures, GPG shows the primary UID of  
that key at display time.  In other words, if you sign a key with one  
primary UID, then make another UID primary, the display will change to  
show the new primary.

There is, incidentally, a way of encoding which UID the signer "meant"  
the signature to be from.  It's part of the OpenPGP standard, but no  
software that I know of actually uses it.


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