Introduction: OS packages are currently signed by hashing with SHA256, then using Ed25519 or RSA to produce a signature. Moving forward, both of the existing approaches towards signing should be deprecated in favor of signatures that can be Sigsum-logged. Considering that there's going to be an OS-package format refactoring, now would be a good time to ensure that the signature on the new blob becomes Sigsum-compatible. And further, the sigsum log server protocol is now at version 1. So there's a stable interface to implement.

Roughly the steps needed:

• Propose sigsum-compatible signature format (and consider what to do with the old ways of signing)
• Refactor so our tooling can sign with this format
• Refactor so stboot accepts this format

The above should not require any other changes to, e.g., trust policy.

Then:

• Propose how to incorporate sigsum into ST's trust policy, maybe /etc/trust_policy/sigsum and an on-off toggle in /etc/trust_policy/trust_policy.json or similar?
• Add support for sigsum logging to happen with our tooling (i.e., not just signing)
• Add support for enforcing sigsum logging in stboot

Any monitoring that is now possible is considered out-of-scope, this milestone is already large as-is. (There's always the next milestone.)

Open questions:

• The proposals, obviously.
• How this fits into / on-top OS package refactoring. Can we assume that signing will look roughly the same as today, it's just a different blob?

We will figure this out while working on the proposal, but if you have any input already please provide it.

The main driver to ensure this moves forward: nisse with rgdd as rubberduck.

EDIT 2024-01-12: closing, this is now in our backlog instead. Created system-transparency/project/documentation#40 (closed).