In the JWT spec the value of "typ" SHOULD be "jwt".   That indicates as Mike 
stated that it is a JWT in compact format that has as its body a jwt claim set. 
  If the claim set is signed then encrypted, the inner JWT has a a typ of jwt 
and no cty , and the outer one has a typ of JWT and a cty of jws.

If a JOSE object has a typ of jws then one would assume that it is a jws in 
compact serialization with some other body type then a jwt claimset.

I think this is somewhat a symptom of the JWT and JOSE specs getting split into 
different WG.

So Mike can correct me but I don't think putting jwe or jws in typ is the 
intended use of that element if you are in fact sending JWT.

I understand where Jim is coming from I think of JWT as a jwt claim-set and JWE 
and JWS as the outer layer, where JWT thinks of itself as a total security 
token definition including overall processing rules for security tokens, with a 
standard envelope segment and JWE or JWS encoding as determined by the alg.

In security token processing knowing that what you have will unwrap to a JWT 
claim-set , rather than to some other thing is quite important.

John B.


On 2013-05-29, at 7:56 PM, Dick Hardt <[email protected]> wrote:

> I use it all the time and my code would barf if it was not there.
> 
> I think it should be required rather than be a hint if it is going ot be 
> there.
> 
> 
> On Wed, May 29, 2013 at 4:40 PM, Jim Schaad <[email protected]> wrote:
> I think the values just changed
> 
>  
> 
> However the way you are using it would be an argument to say that it should 
> be a required field.  Are you just using it as a hint if it exists and then 
> looking at the rest of the fields if it is not present?
> 
>  
> 
> Jim
> 
>  
> 
>  
> 
> From: Dick Hardt [mailto:[email protected]] 
> Sent: Wednesday, May 29, 2013 3:49 PM
> To: Jim Schaad
> Cc: [email protected]
> Subject: Re: [jose] Should we delete the "typ" header field
> 
>  
> 
> Well, I have been using, but now realize the spec changed or I was confused.
> 
>  
> 
> I had been setting "typ" to be either "JWE" or "JWS" depending on the type of 
> token I was creating or parsing as it was easier than looking at "alg"
> 
>  
> 
> As currently defined, I don't see value in "typ".
> 
>  
> 
> -- Dick
> 
>  
> 
>  
> 
> On Wed, May 29, 2013 at 3:02 PM, Jim Schaad <[email protected]> wrote:
> 
> In reading the documents, I am trying to understand the justification for 
> having the “typ” header parameter in the JOSE documents.
> 
>  
> 
> The purpose of the field is to hold the type of the object.  In the past, I 
> believe that values which should now be placed in the cty field (such as 
> “JWT”) were placed in this field as well.  However the parameter is optional 
> and an implementation cannot rely on its being present.  This means that for 
> all practical purposes all of the code to determine the value of the type 
> field from the values of the alg and enc fields.  If the field was mandatory 
> then this code would disappear at a fairly small space cost and I can 
> understand why the parameter would be present.
> 
>  
> 
> Can anybody justify why this field should be present in the document – or 
> should it just disappear?
> 
>  
> 
> Jim
> 
>  
> 
> 
> _______________________________________________
> jose mailing list
> [email protected]
> https://www.ietf.org/mailman/listinfo/jose
> 
> 
> 
> 
>  
> 
> -- 
> -- Dick
> 
> 
> 
> 
> -- 
> -- Dick
> _______________________________________________
> jose mailing list
> [email protected]
> https://www.ietf.org/mailman/listinfo/jose

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