gpg: Add experimental support for an issuer fpr.
* common/openpgpdefs.h (SIGSUBPKT_ISSUER_FPR): New. * g10/build-packet.c (build_sig_subpkt_from_sig): Add arg PKSK and insert the issuer fpr if needed. * g10/sign.c (write_signature_packets): Pass signing key. (make_keysig_packet): Ditto. (update_keysig_packet): Ditto. * g10/parse-packet.c (dump_sig_subpkt): Print issuer fpr. (parse_one_sig_subpkt): Detect issuer fpr. (can_handle_critical): Add issuer fpr. * g10/mainproc.c (check_sig_and_print): Try to get key via fingerprint. * g10/gpgv.c (keyserver_import_fprint): New stub. * g10/test-stubs.c (keyserver_import_fprint): New stub.
This support is enabled with the --rfc4880bis option and intended to
test to recently proposed issuer fpr.
- Signed-off-by: Werner Koch <wk@gnupg.org>