Format of exported subkeys from gnupg

[Hans-Christoph Steiner]

On 07/22/2012 11:59 AM, Werner Koch wrote:
> On Sat, 21 Jul 2012 00:09, abel at guardianproject.info said:
> 
>>> Using GnuPG 2.0.19 my .gnupg/private-keys-v1.d/ directory is empty, is
>>> this expected?
> 
> Unless you use S.MIME it is indeed empty for 2.0.  Only 2.1 uses it also
> for OpenPGP.
> 
>>> Also, what about the method you described is 2.1 specific, ideally we'd
>>> like this to work on 2.0 versions as well, but 2.1 is definitely a start!
> 
> 2.1 will replace 2.0.  Actually our work on the N900 and the HTC Touch
> Pro to port Kontact to them was done using 2.1.  Thus I strongly suggest
> to use 2.1 for any new platforms.

We're trying to parse existing keys on a wide variety of platforms so
that we can convert between various formats.  This an essential part of
our idea to make the gpg key the master crypto identity, and then use
subkeys for various other applications, like OTR, TextSecure, S/MIME,
etc.  Then the user will only need to deal with one single key for trust
relationships.

Right now, we are starting out by generating DSA subkeys in gpg, and
exporting them for use in OTR.  libotr's private key format is a
hex-based S-expression.  The subkey export format for gpg v2.0 is not
clear to us, so any pointers on docs or the place in the gpg code to
figure that out would be most appreciated.

.hc