Thank you for your feedback, Fraser. It would be useful to hear from others
who have implemented the JSON Serializations whether they agree with Fraser or
Richard.
-- Mike
P.S. The list you sent it to reached the editors and chairs. The
[email protected] list reaches the whole JOSE working group.
-----Original Message-----
From: Fraser Tweedale [mailto:[email protected]]
Sent: Tuesday, October 28, 2014 9:11 PM
To: [email protected]
Subject: draft-ietf-jose-json-web-signature ; flattened serialization
Hello,
(I am not familiar with IETF WG processes so I hope I am communicating in a
useful way and in the right place.)
JWS draft 36 adds a "flattened JWS syntax" for the case where there is a single
signature. A similar change was made for JWE in the single recipient case.
Richard Barnes proposed these changes on the following basis:
``I've had several implementors trying to use JWS in the JSON
serialization ask why it was necessary to include a "signatures"
array in cases where there's only one signer. It seems like this is
going to be a major barrier to deployment and re-use.''
I am the author of a Haskell JOSE library
(http://hackage.haskell.org/package/jose) and object to these changes on the
following bases:
- They add substantial complexity to the parsing of JWS and JWE
objects (which is already complex).
- The nature of the "optimisation" for the single-signature case is
unclear. If the optimisation is for compactness, this is obviated
by "7.2. JWE JSON Serialization" which states ``This
representation is neither optimized for compactness nor
URL-safe.'' If the optimisation is for simplicity, it is a false
economy.
- The fact that implementors were asking about this part of the spec
does not imply an impediment to deployment and re-use. (Perhaps
comments to this effect were in fact made, but as written the
justification is speculative.)
The wish for a "simpler" serialization for a common use case is understandable,
but this is a case of "be careful what you wish for". Commentary to the effect
of "the signatures array is used even when there is a single
signature/recipient to keep parsing as simple as possible" would give
implementors the answer to this question and relieve them of the additional
complexity required to support the Flattened Serialization in addition to the
General Serialization.
Please consider reverting this recent change to the specification.
Regards,
Fraser Tweedale
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