gpg: New option --include-key-block.

* common/openpgpdefs.h (SIGSUBPKT_KEY_BLOCK): New.
* g10/gpg.c (oIncludeKeyBlock): New.
(opts): New option --include-key-block.
(main): Implement.
* g10/options.h (opt): New flag include_key_block.
* g10/parse-packet.c (dump_sig_subpkt): Support SIGSUBPKT_KEY_BLOCK.
(parse_one_sig_subpkt): Ditto.
(can_handle_critical): Ditto.
* g10/sign.c (mk_sig_subpkt_key_block): New.
(write_signature_packets): Call it for data signatures.
--

This patch adds support for a to be proposed OpenPGP ferature:

  Introduce the Key Block subpacket to align OpenPGP with CMS.

  This new subpacket may be used similar to the CertificateSet of
  CMS (RFC-5652) and thus allows to start encrypted communication
  after having received a signed message.  In practice a stripped down
  version of the key should be including having only the key material
  and the self-signatures which are really useful and shall be used by
  the recipient to reply encrypted.

  #### Key Block

  (1 octet with value 0, N octets of key data)

  This subpacket MAY be used to convey key data along with a signature
  of class 0x00, 0x01, or 0x02.  It MUST contain the key used to create
  the signature; either as the primary key or as a subkey.  The key
  SHOULD contain a primary or subkey capable of encryption and the
  entire key must be a valid OpenPGP key including at least one User ID
  packet and the corresponding self-signatures.

  Implementations MUST ignore this subpacket if the first octet does not
  have a value of zero or if the key data does not represent a valid
  transferable public key.

GnuPG-bug-id: 4856
Signed-off-by: Werner Koch <wk@gnupg.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/common/openpgpdefs.h b/common/openpgpdefs.h
index 2962fe2d4..5ab45debd 100644
--- a/common/openpgpdefs.h
+++ b/common/openpgpdefs.h
@@ -120,6 +120,7 @@ typedef enum
     SIGSUBPKT_PREF_AEAD     = 34, /* Preferred AEAD algorithms. */
 
     SIGSUBPKT_ATTST_SIGS    = 37, /* Attested Certifications.  */
+    SIGSUBPKT_KEY_BLOCK     = 38, /* Entire key used.          */
 
     SIGSUBPKT_FLAG_CRITICAL = 128
   }