openssh bugs - Jan 2024 - [Bug 3659] New: Certificates are ignored when listing revoked items in a (binary) revocation list

https://bugzilla.mindrot.org/show_bug.cgi?id=3659

            Bug ID: 3659
           Summary: Certificates are ignored when listing revoked items in
                    a (binary) revocation list
           Product: Portable OpenSSH
           Version: 9.2p1
          Hardware: All
                OS: All
            Status: NEW
          Severity: minor
          Priority: P5
         Component: ssh-keygen
          Assignee: unassigned-bugs at mindrot.org
          Reporter: webmaster at mmf-research.de

1. Create a blank binary revocation list:
  ssh-keygen -Qlf my.krl
  # KRL version 0
  # Generated at 20240122T162948

2. Revoke a key, and a certificate:
  ssh-keygen -kuf my.krl user1_id25519.pub user2_id25519-cert.pub
  Revoking from user1_id25519.pub
  Revoking from user2_id25519-cert.pub

3. Check the successful revocation:
  ssh-keygen -Qf my.krl user1_id25519.pub user2_id25519-cert.pub
  > user1_id25519.pub (USER1 ID): REVOKED
  > user2_id25519-cert.pub (USER2 ID): REVOKED

4. Displaying the updated content of the revocation list will ignore
the certificate:
  ssh-keygen -Qlf my.krl
  # KRL version 0
  # Generated at 20240122T162948
  hash: SHA256:SHA256:3IJIl... # ssh-ed25519
  # CA key ssh-ed25519 SHA256:f4o3Bp...
  serial: 3007

I would expect the revoked certificate to show up in this list, too.
Note that in my setup, the SSH daemon correctly denies login with the
revoked certificate. It seems that just the KRL/CRL content listing is
affected.

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https://bugzilla.mindrot.org/show_bug.cgi?id=3659

Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |WORKSFORME
             Status|NEW                         |RESOLVED
                 CC|                            |djm at mindrot.org

--- Comment #1 from Damien Miller <djm at mindrot.org> ---
This is working correctly.

You revoked two keys. A plain public key that is revoked by its hash:

hash: SHA256:SHA256:3IJIl... # ssh-ed25519

and a certificate. The certificate is revoked by its CA key and serial
number, that is the last two lines of your output:

# CA key ssh-ed25519 SHA256:f4o3Bp...
serial: 3007

So both keys are definitely represented in the KRL dump.

Generally, the KRL code tries to write as small a file as possible. For
Certificates this means that it uses the smallest unique identifier
which is the serial number (for each given CA.

If you don't like this then you can use a KRL spec file to control how
the KRL revokes the keys. Something like:

(printf "sha256: "; cat user1_id25519.pub; \
 printf "\nsha256: "; cat user2_id25519-cert.pub; printf
"\n") >
krl.spec
ssh-keygen -kuf my.krl krl.spec

See the "KEY REVOCATION LISTS" section of the ssh-keygen(1) manpage
for
more information on KRL spec files.

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