rfc: application level verification

[burgerdev]

Rendered: https://github.com/edgelesssys/contrast/blob/rfc/012/rfc/012-application-level-verification.md

[burgerdev]

We also have

contrast/sdk/verify.go

Lines 99 to 109 in dda33d5

	// CoordinatorState represents the state of the Contrast Coordinator at a fixed point in time.
	type CoordinatorState struct {
	// Manifests is a slice of manifests. It represents the manifest history of the Coordinator it was received from, sorted from oldest to newest.
	Manifests [][]byte
	// Policies contains all policies that have been referenced in any manifest in Manifests. Used to verify the guarantees a deployment had over its lifetime.
	Policies [][]byte
	// PEM-encoded certificate of the deployment's root CA.
	RootCA []byte
	// PEM-encoded certificate of the deployment's mesh CA.
	MeshCA []byte
	}

Might be good to consolidate this into a shared type.

[thomasten]

If I --disable-updates, I don't need to check anything myself, right?

[burgerdev]

--disable-updates results in a manifest without workload owner keys. However, that state can also be reached by just setting a manifest without workload owner keys on an existing coordinator history. If you care about that (which you only need to if you're relying on workload secrets, imho), you should validate that the history has only one manifest.