Series of minor questions about OpenPGP 2

[David Shaw]

On Thu, Jan 29, 2009 at 05:22:01PM +0100, Peter Thomas wrote:
> Hi David.
> 
> One more thing on this:
> 
> On Tue, Jan 27, 2009 at 5:18 AM, David Shaw <dshaw at jabberwocky.com> wrote:
> >> Would gnupg understand these subpackets in a 0x1F signature?
> > Yes.  It's a valid key as per the spec, even though no program actually
> > generates such a key that I know of.  Note that I can't make that same
> > guarantee for other programs.  I suspect they'd work, but you'd have to
> > check to be sure.
> I had already wrote in another message that I'm trying to do some
> interoperability tests (with large keysizes for example).
> I'd also like to play with these signature types (0x1F, 0x13 and even
> 0x18 !) a little bit especially the with the subpackets:
> preferred symmetric/hash/compression algorithms, policy URI and key flags
> (I think it would even make semantic sense to put them on 0x18s).
> 
> Anyway to do this I need to generate those signatures (of course) and
> I'd like to use the wonderful code of gnupg :-)
> Could you perhaps point me to the useful function names where I can
> modify these signatures (0x1F,0x13,0x18) and the functions that are
> used to inject subpackages?
> Was a great help when you pointed me to the write_header()/etc
> functions before :-)

build-packet.c:build_sig_subpkt()
sign.c:make_keysig_packet()
sign.c:update_keysig_packet()

David