ZIP-221/244 auth data commitment validation in checkpoint verifier

[conradoplg]

Motivation

ZIP-221 specifies a history tree to which each block must commit to. ZIP-244 expands this commitment to also include the authentication data commitment.

This adds this check to the checkpoint verifier, as a follow up to #2609

Specifications

See #2609

Designs

N/A

Solution

Since it would be difficult to add this logic directly to the checkpoint verifier, this adds the check to the finalized state (since, at the end, the checkpoint verifier commits to the finalized state). This is because we need the history tree, and the finalized state already has one.

Review

I think @teor2345 will want to review this.

There are no tests currently. I'll discuss a possible strategy in the chat, then we can decide if we add the test here or create a ticket for it.

Reviewer Checklist

• Code implements Specs and Designs
• Tests for Expected Behaviour
• Tests for Errors

Follow Up Work

Follow up to #2609

[teor2345]

This looks pretty good. I like the way this PR re-uses the existing check code.

I have one blocking question about a potential denial of service/hang.
And an optional suggestion for some documentation.

[teor2345]

This code looks pretty good, and you're right, it's surprisingly simple.

I think we'll need to reset the initial_tip_hash as well as verifier_progress.

[teor2345]

I think we've made some good progress here, and the remaining work can be done later in other tickets.

I have a bunch of optional suggestions and questions, but feel free to merge with all or none of them done.

[conradoplg]

Another round of changes!

Yes I agree we can leave this as is, I've created the other tickets as mentioned in the comment.

I also fixed a bug (in partial_chain_strategy()) that was causing CI to fail.

[teor2345]

I'm good with this, just waiting on whatever we decide to do with the metrics.

Feel free to merge after you've done whatever you want there.