Re: [jose] proposal: put encryption header parameters into a separate object

Bob / Richard

Including the signature value and the ciphertext in the JSON would needlessly enlarge the resulting token as it was base64url encoded.

Having the header use a hierarchical structure seems to make it easier to support multiple keys, which is needed if you want to sign and encrypt a message -- which seems to be a common use case!

-- Dick

On Nov 9, 2012, at 8:29 AM, Bob Wyman <bob@wyman.us> wrote:

> The "val" element in Barnes' proposal would need some parameters (typ, cty, etc.) as well as the content in val:
> 
> {
>   "enc": { /* encryption parameters */ },
>   "sig": { /* signature parameters + value */ },
>   "val": {/* content parameters + plaintext */}
> }
> 
> 
> 
> On Fri, Nov 9, 2012 at 1:58 AM, Richard L. Barnes <rbarnes@bbn.com> wrote:
> Hey Dick,
> 
> To make sure I understand your use case correctly: You want to convey an encrypted object, as well as a signature over the plaintext (without having to encrypt the signature value).  Does that sound accurate?
> 
> It seems like there are three types of information you want in the object: (1) cipher text, (2) encryption parameters, and (3) signature value/parameters.  So why not encapsulate it like that?  To propose a JSON syntax:
> 
> {
>   "enc": { /* encryption parameters */ },
>   "sig": { /* signature parameters + value */ },
>   "val": "/* ciphertext */"
> }
> 
> Obviously:
> -- JWE/JWS could be the special cases where only one of "enc" or "sig" is present
> -- This cleanly supports multiple signatures via multiple "sig" values (e.g., in an array)
> -- This cleanly supports multiple recipients via multiple "enc" values (e.g., in an array)
> -- You could leave one of "enc" or "sig" parameters as flat lists (as in JWS/JWE), but it seems cleaner to have them parallel
> -- For a compact serialization, you would want certain fields to be not double-base64'ed.  We can figure that out later :)
> 
> This seems like kind of an appealing line of reasoning to me.  I would be glad to do some work on figuring out the details.
> 
> --Richard
> 
> 
> 
> 
> On Nov 7, 2012, at 3:23 PM, Dick Hardt <dick.hardt@gmail.com> wrote:
> 
> > To enable encrypting and then signing of the same token, we need to specify the encrypting and signing algorithms separately.
> >
> > Since we are using JSON, how about if we create an encryption object to contain all the parameters defined in JWE so that there is no overlap in the JWS namespace.
> >
> > "enc":
> >       {  "alg"
> >       ,  "enc"
> >       ,  "zip"
> >       }
> >
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> > jose@ietf.org
> > https://www.ietf.org/mailman/listinfo/jose
> 
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