Sorry I'm so late in making a suggestion for the list, since it's in the
final call phase.
It seems to me that a key revocation is important enough that people
might want to know why it was revoked. Especially if it was compromised,
since they might want to be put on notice that an adversary may try to
use the key. Accordingly, I'd like to propose the following subpacket
type for inclusion in key revocation signatures.
------------------
Reason for revocation
(1 octet of revocation code, N-1 octets of reason string)
This subpacket is used only in key revocation and certification
revocation signatures. It describes the reason why the key or
certificate was revoked.
The first octet contains a machine-readable code which represents
the reason for the revocation, from the following list:
0x00 - No reason specified (key revocations or cert revocations)
0x01 - Key is superceded (key revocations)
0x02 - Key material has been compromised (key revocations)
0x03 - Key is no longer used (key revocations)
0x20 - User id information is no longer valid (cert revocations)
Following the initial octet is an optional string of octets which
gives information about the reason for revocation in human-readable
form. The length of this octet string is one less than the size of
the subpacket.