Re: [Suit] draft-moran-suit-manifest-02

[Carsten Bormann <[e-mail]>]

On Jul 4, 2018, at 10:26, Rønningstad, Øyvind <[e-mail]> wrote:
> 
> 	• CDDL nitpicking:
> 		• Some name inconsistencies: ProcessingStep vs Processor, TargetInfo vs Target.
> 		• There's probably a typo in the definition of Directive. Should it be an array of maps?
> 		• Target::storageIdentifier and Target::componentIdentifier don't use the custom types for StorageIdentifier and ComponentIdentifier.
> 		• I think digests should have a type, so the user can more easily restrict its format after choosing a digest algorithm.
> 		• Suggestion: Add nint to textKeys group.
> 		• AuthenticatedManifest should probably contain an authenticatedManifestVersion or similar.
> 		• "Processor" might be confusing (“does it mean CPU?”).

It also helps to occasionally run instances of formal languages through some tool to check them…

Apart from inconsistent use of names, most of the syntax errors stem from the arcane syntax that CDDL is using for its workaround for not having true enumerations (Section 2.2.2.2 of draft-ietf-cbor-cddl-03.txt); this requires commas (or nothing) instead of slashes, and an enclosing &, so with Øyvind’s suggestion, textKeys becomes, e.g.:

  textKeys = &(
      uninitialised: 0
      manifestDescription: 1
      payloadDescription: 2
      vendorName: 3
      modelName: 4
      payloadVersion: 5
  ) / nint

And Processor starts off as:

  Processor       = [
      &(decrypt: 1, decompress: 2, undiff: 3, relocate: 4, unrelocate: 5),


(Of course, the same thing can be expressed as:

  Processor       = [
      &(decrypt: 1, decompress: 2, undiff: 3, relocate: 4, unrelocate: 5),
      decrypt: 1 // decompress: 2 // undiff: 3 // relocate: 4 // unrelocate: 5,

Not sure what the intent is here; in the first case, I’d probably also add a label, as in

  Processor       = [
      process: &(decrypt: 1, decompress: 2, undiff: 3, relocate: 4, unrelocate: 5),

I have attached a version that parses (I don’t think an attachment will make it to the lists) but does not address any other of Øyvind’s suggestions.

The other problem that should probably be addressed is that most rules are unused — there would need to be one cddl file for the manifest, and maybe one for the COSE envelope.  We simply don’t have a good way in CDDL yet to say “Manifest goes through an algorithm and turns up in COSE_Sign” — actually, in this case this could be solved in part as the manifest turns up in cleartezt.
I have included a dirty hack in the attached which I intend to fix.

I’m CCing the CBOR WG to give an example for CDDL being used in another WG.  If you want to discuss a CDDL feature, please strike SUIT from the list (and if you want to discuss a SUIT feature, maybe strike CBOR from the list).

Grüße, Carsten