Re: [Unbearable] Benjamin Kaduk's No Objection on draft-ietf-tokbind-https-15: (with COMMENT)
Dirk Balfanz <balfanz@google.com> Wed, 06 June 2018 04:41 UTC
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From: Dirk Balfanz <balfanz@google.com>
Date: Tue, 05 Jun 2018 21:41:03 -0700
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To: Benjamin Kaduk <kaduk@mit.edu>
Cc: The IESG <iesg@ietf.org>, draft-ietf-tokbind-https@ietf.org, John Bradley <ve7jtb@ve7jtb.com>, tokbind-chairs@ietf.org, Tokbind WG <unbearable@ietf.org>
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Subject: Re: [Unbearable] Benjamin Kaduk's No Objection on draft-ietf-tokbind-https-15: (with COMMENT)
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Hi Benjamin, thanks for the feedback. Most of it is addressed in the new draft ( https://tools.ietf.org/html/draft-ietf-tokbind-https-16) See below (inline) for details. On Thu, May 10, 2018 at 6:51 AM Benjamin Kaduk <kaduk@mit.edu> wrote: > Benjamin Kaduk has entered the following ballot position for > draft-ietf-tokbind-https-15: No Objection > > When responding, please keep the subject line intact and reply to all > email addresses included in the To and CC lines. (Feel free to cut this > introductory paragraph, however.) > > > Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html > for more information about IESG DISCUSS and COMMENT positions. > > > The document, along with other ballot positions, can be found here: > https://datatracker.ietf.org/doc/draft-ietf-tokbind-https/ > > > > ---------------------------------------------------------------------- > COMMENT: > ---------------------------------------------------------------------- > > I agree with Alexey about clarifying that backslashes are only for > readability. > Addressed in the new draft. > > I'm curious why Section 2 limits to at most one referred_token_binding. > We couldn't come up with examples where we would have more than one, and wanted to write the spec as narrow as possible for now. > > > Section 2 > > A TokenBindingMessage is validated by the server as described in > Section 4.2. ("Server Processing Rules") of > [I-D.ietf-tokbind-protocol]. > > Nit: no period after "4.2". > Addressed in new draft. > > [...] If validation fails and a Token Binding > is rejected, any associated bound tokens MUST also be rejected by the > server. > > I repeat my remark about "associated" from tokbind-protocol. > > > Section 2.1 > > It seems a little unusual to see "Applications other than Web > browsers MAY [...]", though I do not object. > > > Section 3 > > To be clear, this means that the EKM used is the one from before > the renegotiation, corresponding in the somewhat-common use case of > renegotiation for optional client authentication to the > unauthenticated-client state, right? > See previous answers from Nick et al. It's a new EKM. > > > Section 5.3 > > As illustrated in Section 5.5, when a client receives this header > field, it should take the TokenBindingID of the provided TokenBinding > from the referrer and create a referred TokenBinding with it to > include in the TokenBindingMessage on the redirect request. In other > words, the Token Binding message in the redirect request to the Token > Provider now includes one provided binding and one referred binding, > the latter constructed from the binding between the client and the > Token Consumer. > > I'm not really an HTTP expert, but is "redirect request" the right > term (as opposed to, say, "redirected request" or "post-redirect > request")? > > The TokenBindingMessage SHOULD contain a TokenBinding with > TokenBindingType referred_token_binding. > > At this point we may have lost track of what "The > TokenBindingMessage" refers to -- some explicit scope (the message > sent to the Token Provider after following the redirect) could be > helpful. > Addressed in new draft. > > > Section 7.1 > > The goal of the Federated Token Binding mechanisms is to prevent > attackers from exporting and replaying tokens used in protocols > between the client and Token Consumer, [...] > > Do we actually need to limit the scope to Token Consumer? The Token > Provider may also issue tokens that we want to protect, after all. > Correct - and that’s covered in the more general version of this consideration in draft-ietf-tokbind-protocol. Here we point out that the federation mechanism in particular focuses on the client<->Token Consumer connection. > > > Section 7.2 > > Do we need to repeat the normative statements already made in > [TBPROTO]? Maybe we can just say that [TBPROTO] requires these > things to be used, to protect against [TRIPLE-HS]. > Addressed in new draft. Thanks again for your thoughtful comments! Dirk.
- Re: [Unbearable] Benjamin Kaduk's No Objection on… Dirk Balfanz
- [Unbearable] Benjamin Kaduk's No Objection on dra… Benjamin Kaduk
- Re: [Unbearable] Benjamin Kaduk's No Objection on… Nick Harper
- Re: [Unbearable] Benjamin Kaduk's No Objection on… Benjamin Kaduk
- Re: [Unbearable] Benjamin Kaduk's No Objection on… Andrei Popov