Hi Anders,

Thanks for jumping in.

The example you provide below is actually quite interesting and related to a 
question I posted to the list a few days ago (see 
https://mailarchive.ietf.org/arch/msg/cose/9nowDz5kbfUvrGR-o6U1Tm31XAA/).

I am not sure whether the intention of Tobias & Mike are actually to re-define 
the way how encryption is accomplished. They should confirm.

Ciao
Hannes

From: Anders Rundgren <[email protected]>
Sent: Thursday, March 3, 2022 8:39 AM
To: Laurence Lundblade <[email protected]>; Mike Jones 
<[email protected]>
Cc: Hannes Tschofenig <[email protected]>; Tobias Looker 
<[email protected]>; [email protected]
Subject: Re: [COSE] Newly Submitted Draft - CBOR Web Token (CWT) Claims in COSE 
Headers

On 2022-03-02 19:33, Laurence Lundblade wrote:
Makes sense to me. Helps out for the EAT claim named “profile” which gives 
information about the type of the token you might want before fully verifying 
it. Addresses an issue Anders brought up about the profile claim.

Not so fast  :)  I brought up a bunch of things which can be illustrated by 
this (just implemented...) example of an encryption object:

211(["https://example.com/myobject";<https://example.com/myobject>, {
  / COSE content encryption algorithm = A256GCM /
  1: 3,
  / Key encryption container /
  2: {
    / COSE Key encryption algorithm = ECDH-ES+A256KW /
    1: -31,
    / Key identifier /
    3: "mykey",
    / Ephemeral key /
    5: {
      / COSE Key type = OKP /
      1: 1,
      / COSE Curve = X25519 /
      -1: 4,
      / COSE X coordinate /
      -2: h'33a04b83d4428824b6d5477522d4a88fac4441122bc46136c0203faa308c3929'
    },
    / Encrypted key /
    10: 
h'e08977c25aeccaecd63b3367de2e2b8f700c82e098ad1e5099d9db510920ccff14debf820427e4ba'
  },
  / Tag /
  8: h'59a84826983e3247fbec4295f75cc138',
  / IV /
  9: h'fd8556c122cff2bc128d5119',
  / Encrypted data /
  10: 
h'e16b16c29da5163eb0131dd1f10f080f8850f55df2ae9d89a3b839ad50952858445f290dfb60'
}])

The core of this builds on Deterministic CBOR which unleashes the true power of 
CBOR in a way legacy solutions do not.   The enhancements include:

  *   Eliminating wrapping of header and (unencrypted) application data.
  *   Using the entire container (modulo the algorithm output variables which 
are added lastly) as input to a signature process and to the authentication 
part of an encryption process.  In the example that includes the top-level CBOR 
tag as well.  cryptoOperation(cborObject.encode()) is all that it takes on the 
encoder's side.
This is pretty much what the X.509 folks have been doing from the very start so 
there is close to zero innovation here 😁

In the example I have also used a URL as profile/object type indicator since 
IANA CBOR custom tag 1537244 or whatever you end-up with, simply isn't pretty 
enough :)  To be more serious: URLs are decentralized and would in this context 
probably be browseable as well.

Cheers,
Anders
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