Daniel A. Nagy writes:
Since I am currently implementing an OpenPGP compliant timestamping service,
I would like to solicit opinions on the issue even without suggesting
immediate changes to the standard. In particular, I would like to know how
various implementations treat 0x40 signatures when encountering them during
signature verification?
Looking at the commercial PGP parsing code, it doesn't look like it
will handle these signatures very well if they occur in a document.
In a key ring I think it will just ignore them, but in a document it
only expects type 0 or 1 signatures. Anything above that is assumed
to be a key signature, in the document parsing code, and it will divert
to the key signature parsing code; but it does not expect to find a key
signature except following other key ring packets. So it will trigger
a parsing error and the message will be rejected as malformed.
This code has worked like this for a number of years so there is probably
a substantial installed base.
Hal Finney