Re: [Suit] Suit manifest with variable recipients

[Michael Richardson <[e-mail]>]

Brendan Moran <[e-mail]> wrote:
    > The result is that COSE_Recipients MUST be held outside of the
    > manifest’s chain of trust. This complicates matters somewhat. It would
    > be better if most of the COSE_Encrypt was held under the trust umbrella
    > while the COSE_Recipients were held outside the umbrella. However, COSE
    > does not support detached Recipient lists. This may be a failing of
    > COSE, and perhaps it should be discussed there. In the interim,
    > however, SUIT needs to move forward with some solution to deploying
    > variable recipient lists.

I think it is reasonable that SUIT give COSE a clear set of requirements.
(Let's not do CBOR packed goof again)

    > I can see several options:


    > Option 1: Place the COSE_Encrypt outside the manifest, reference it by
    > URI (remote) or Integer (envelope) Modify
    > suit-parameter-encryption-info to take a tstr (URI) or integer
    > (Envelope Reference)

    > This means that all devices supporting the encryption-info parameter
    > MUST support both integrated, detached local, and detached remote
    > modes. I don’t think this is really in the spirit of SUIT.

I see your point.

    > Option 2: Place the COSE_Encrypt outside the manifest, reference it by
    > Integer (envelope) Add a new suit-parameter-encryption-info-detached
    > that takes the integer (Envelope Reference)

    > This has the benefit of being unambiguous. However, it creates a new
    > problem: what happens if both the
    > suit-parameter-encryption-info-detached and the
    > suit-parameter-encryption-info are set? Does there need to be a rule
    > that one explicitly unsets the other? How does that work with
    > permissions?

It sounds to me that either it's invalid (manifest rejected outright), or one
simply has a higher priority than the other.

    > Option 3: Abuse COSE slightly: Place a COSE_Encrypt0 in the
    > manifest. Place a list of recipients outside the manifest.

    > This has the benefit of being what we actually want, but it probably
    > won’t play nice with COSE libraries.

I think that few devices will have totally generic COSE libraries anyway.
Encoders can cope.


--
Michael Richardson <[e-mail]>   . o O ( IPv6 IøT consulting )
           Sandelman Software Works Inc, Ottawa and Worldwide