Construction of SUIT_Envelope of URI outside the digest region about teep-protocol

[hisanak]

How about this one? Mimicking example 2 in suit-manifest, this example allows the TAM to change the distribution uri freely.
The points are:

1. severs suit-install containing distribution uri
2. doesn't set the digest of the severed element (suit-install) to change the distribution uri
3. clarifys that the firmware author delegates device operator to decide distribution uri by setting uri = Null in suit-common-sequence

SUIT_Envelope = {
  / manifest / 3:bstr .cbor ({
    / common / 3:bstr .cbor ({
      / components / 2:[
        [h'00']
      ],
      / common-sequence / 4:bstr .cbor ([
        / directive-set-parameters / 19,{
          / uri / 21:Null / Points#3. Clarify the uri will be overridden below (in severed suit-install). /,
        },
        / directive-override-parameters / 20,{
          / image-digest / 3:bstr .cbor ([
            / algorithm-id / 2 / "sha256" /,
            / digest-bytes / h'(digest of image)'
          ]),
          / image-size / 14:34768
        }
      ])
    }),
    / install / 9:[] / Points#2. The digest of severed suit-install SHOULD NOT be set in order to change the uri by TAM's will. /
  }),
  / install / 9:bstr .cbor ([ / Points#1. TAM CAN change severed and not digested suit-install. /
    / directive-override-parameters / 20,{
      / uri / 21:'http://set.by.not.author.but.tam/firmware',
    }
  }
}

The 3rd point requires suit-manifest to change the type of suit-parameter-uri.

--- a/draft-ietf-suit-manifest.cddl
+++ b/draft-ietf-suit-manifest.cddl
@@ -215,7 +215,7 @@ SUIT_Parameters //= (suit-parameter-compression-info
 SUIT_Parameters //= (suit-parameter-unpack-info
     => bstr .cbor SUIT_Unpack_Info)
 
-SUIT_Parameters //= (suit-parameter-uri => tstr)
+SUIT_Parameters //= (suit-parameter-uri => (tstr // Null))
 SUIT_Parameters //= (suit-parameter-source-component => uint)
 SUIT_Parameters //= (suit-parameter-run-args => bstr)

[dthaler]

@bremoran this looks like more of a comment/question on the SUIT manifest draft rather than the TEEP protocol spec

[mcd500]

@bremoran @dthaler let's discuss this at IETF 110 TEEP session, since this is use-cases of SUIT manifest in TEEP

[mcd500]

Fixed in #161