Re: [jose] Should we delete the "typ" header field

[John Bradley <[e-mail]>]

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 <[e-mail]> wrote:

> I use it all the time and my code would barf if it was not there.
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> I think it should be required rather than be a hint if it is going ot be there.
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> On Wed, May 29, 2013 at 4:40 PM, Jim Schaad <[e-mail]> wrote:
> I think the values just changed
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> 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?
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> Jim
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> From: Dick Hardt [mailto:[e-mail]] 
> Sent: Wednesday, May 29, 2013 3:49 PM
> To: Jim Schaad
> Cc: [e-mail]
> Subject: Re: [jose] Should we delete the "typ" header field
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> Well, I have been using, but now realize the spec changed or I was confused.
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> 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"
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> As currently defined, I don't see value in "typ".
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> -- Dick
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> On Wed, May 29, 2013 at 3:02 PM, Jim Schaad <[e-mail]> wrote:
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> In reading the documents, I am trying to understand the justification for having the “typ” header parameter in the JOSE documents.
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> 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.
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> Can anybody justify why this field should be present in the document – or should it just disappear?
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> Jim
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> -- 
> -- Dick
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> -- 
> -- Dick
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