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Re: questions: packet tag or content tag (4.3), what is placed in hashed subpacket field (5.2.3), critical bit (5.2.3.1



In <200005221536.IAA01210@xxxxxxxxxx>, on 05/22/00 
   at 09:36 AM, hal@xxxxxxxxxx said:

>> so is the signing key id the only subpacket that is allowed to go in
>> the unhashed area?

>No, anything which might reasonably be considered to be "advisory" and
>not security critical could go there.  For example the URL where the cert
>can be found.  I don't know if there is an exhaustive list. The point is
>that the software needs to be aware that material in the unhashed region
>is not authenticated and could have been tampered with.

>> also, for a given subpacket type, can instances of
>> that subpacket appear in either the hashed subpacket field or the
>> unhashed subpacket field, or is it a mutually exclusive situation?

>I don't see any problem in allowing that.

As an open question to list members:

What do you consider the proper response of OpenPGP software (client &
server) when an established key (ie a key on the server or users keyring)
is "updated" and unhashed data has been changed?

Take the example:

Software A lets the user enter on his key the prefered URL to obtain his
key on the self-sig for his key and the software stores it in an unhashed
subpacket.

The user distributes his key (other users, servers, ...ect).

Software A also allows the user to change this at a later date without
creating a new signature.

The user distributes this "updated" key.

How should the receiving software treat this "updated" data?

-- Ignore the "new" data

-- Accept the "new" data in place of the old data

-- Notify the receiver that there is "new" data and let him decide

-- ....?

-- 
---------------------------------------------------------------
William H. Geiger III      http://www.openpgp.net  
Geiger Consulting    

Data Security & Cryptology Consulting
Programming, Networking, Analysis
 
PGP for OS/2:               http://www.openpgp.net/pgp.html
E-Secure:                   http://www.openpgp.net/esecure.html
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