We have something for ECC that seems to "work" for those who have a use case for ECC. New parameters "that one COULD specify" are not in the current draft.
From: [email protected] [mailto:[email protected]] On Behalf Of Anthony Nadalin Sent: Friday, July 27, 2012 10:49 PM To: Nennker, Axel; Mike Jones; [email protected]; [email protected] Cc: [email protected] Subject: Re: [jose] MUST understand ALL header fields So not sure this is at all possible for all the permutations that there might be for all the parameters that one could specify for ECC From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Friday, July 27, 2012 1:30 AM To: Mike Jones; [email protected]; [email protected] Cc: [email protected] Subject: Re: [jose] MUST understand ALL header fields I agree with Breno's analysis and support to ditch extensibility. Instead the JWA must specify which alg/enc/int algorithm needs what mandatory parameters. JWTs with a header with unknown parameters must be rejected. If somebody needs to new algorithms or new extra parameters they should write a new draft. With all the interoperability issues that this implies... If later somebody finds that one alg/enc/int from this spec is not secure enough then the implementations need to decide whether they can take the risk to continue to support it or pull it. My hope is that our current set of specified algs/encs/ints is broad enough that a secure alternative exists if this ever happens. The cost for extensibility is too high and there is a real danger that this WG gets stuck like the OAUTH-WG for years. Let's specify something that is useful now. Axel From: [email protected]<mailto:[email protected]> [mailto:[email protected]]<mailto:[mailto:[email protected]]> On Behalf Of Mike Jones Sent: Thursday, July 26, 2012 7:39 PM To: Breno de Medeiros; Manger, James H Cc: [email protected]<mailto:[email protected]> Subject: Re: [jose] MUST understand ALL header fields I agree with this analysis. If there's an explicit way defined to indicate which additional header parameters may be ignored, that would be OK. Allowing ignore-by-default would be a recipe for disaster. -- Mike From: [email protected]<mailto:[email protected]> [mailto:[email protected]]<mailto:[mailto:[email protected]]> On Behalf Of Breno de Medeiros Sent: Thursday, July 26, 2012 10:35 AM To: Manger, James H Cc: [email protected]<mailto:[email protected]> Subject: Re: [jose] MUST understand ALL header fields Put it another way: If we want the JWT security header to be extensible we need to define an explicit extension mechanism. It is NOT sufficient to say MUST ignore non-understood fields in the header. This will make it impossible to write secure implementations of validation libraries in practice. An extension mechanism would define: - How to bundle fields of an extension as a single object. - How to indicate that this object is an extension, and whether the extension is critical (can't be safely ignored) or not. You can't get extensibility cheaply in a security spec. A choice is needed whether to support extensibility explicitly (at the expense of significant increase of spec complexity, since a lot will have to be spelled out right now) or not. Giving up clear security semantics to get cheap extensibility is not an acceptable 3rd option. On Thu, Jul 26, 2012 at 9:16 AM, Breno de Medeiros <[email protected]<mailto:[email protected]>> wrote: On Wed, Jul 25, 2012 at 10:28 PM, Manger, James H <[email protected]<mailto:[email protected]>> wrote: Breno, >> How about stapling an OCSP response to a JOSE message? > That's a more compelling use case -- it's security-specific but only adds to > the security validation context. How about the signing time? How about some DNS records with DANE and DNSSEC info giving evidence that the public key is associated with a domain? How about a blob of data related to Sovereign Keys, or Perspectives, or Convergence, or some other proposal to bolster PKI? How about a domain_parameter_seed so you can verify that the common domain parameters (eg p & q in DSA) were not chosen to have special properties? How about data to allow you to validate a public key (eg co-factor for EC? Something complicated for RSA?)? How about a timestamp from a timestamp service? I'm not sure which, where, or when an item like the ones mentioned above will be needed. I am confident that someone will need some items like these. When that happens they should have a choice about whether including the item needs to break interop with all existing receivers. A mode field that MUST be understood (eg "t":"sig") coupled with MUST ignored any unrecognized parameters keeps our future choices open. That's not good enough for a security spec. If fields are added and not all MUST be understood, then we need explicit syntax about what fields are to be ignored when not understood. E.g., in X509 certificates, extensions (while optional) have the ability to declare themselves critical, so that implementations that don't understand that extension MUST reject the certificate as invalid. > However declaring that any header you don't understand could be optional is a > far worse balance on the extensibility versus simplicity spectrum (where > simplicity here is a stand-in for security, interoperability, etc.) I'm not sure I understand this "simplicity" argument. Ignoring unrecognized fields is the simplest implementation choice. Is your idea that if you tightly constrain extensibility (by making them MUST understand) then messages will not accumulate as many "enhancements" of dubious value. That is, over time a MUST ignore rule allows messages to get more complex (and hence less secure/interoperable). Do you want "MUST understand" to strongly discourage people misusing the header to carry content metadata, for instance? Inevitably, a field will be added that shouldn't be ignored because it modifies the meaning of some other widely understood header entry, followed by usual antics and general perplexity. -- James Manger From: Breno de Medeiros [mailto:[email protected]<mailto:[email protected]>] Sent: Thursday, 26 July 2012 1:12 PM To: Manger, James H Cc: [email protected]<mailto:[email protected]> Subject: Re: [jose] MUST understand ALL header fields That's a more compelling use case -- it's security-specific but only adds to the security validation context. There may be a case to define optional entries in the JWT header. However declaring that any header you don't understand could be optional is a far worse balance on the extensibility versus simplicity spectrum (where simplicity here is a stand-in for security, interoperability, etc.) So I am not convinced that losing the ability to declare OCSP bindings in JWTs justifies dropping the MUST language. If there is rough consensus that defining optional security fields in the header is prudent from the viewpoint of future spec extensibility then we should devise some simple way to declare a JWT header field optional and exempt _only_those_ from the MUST fail when not understanding clause. Changing the default behavior even to SHOULD appears to me to sacrifice too much on the altar of extensibility. On Wed, Jul 25, 2012 at 7:38 PM, Manger, James H <[email protected]<mailto:[email protected]>> wrote: How about stapling an OCSP response to a JOSE message? Why should that be "MUST understand"? -- James Manger -- --Breno -- --Breno -- --Breno
_______________________________________________ jose mailing list [email protected] https://www.ietf.org/mailman/listinfo/jose
