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Re: [Hipsec] draft-ietf-hip-cert-02-pre00



Hi.

Comments inline.

Am 22.10.2009 um 08:16 schrieb Samu Varjonen:

Henderson, Thomas R kirjoitti:
2) elements of procedure for exchanging CERTs, or requesting that the peer provide a CERT.

This has been discussed but for some reason we put it into hip- service-00. Do you think hip-cert should have its own way of asking the certificates or could it use hip-service-00? The functionality would overlap with the hip-service-00.

The HIP hip-service-00 draft presents a general way of notifying end- hosts about requirements and properties of a service and allows some simple negotiations. Requesting certain certificates was one of the main reasons for writing the draft. However, we felt that more general negotiations would be out of scope for the hip-crt draft. The draft has not been advanced because we got very little comments on which services people would/could use. If needed we can narrow down the types of services that can be negotiated and focus on the signaling of the certificate first but I wouldn't really want to abandon a more general use of the HIP service parameter.


So, I'm guessing that David has the first use case in mind, that the CA need not even be HIP aware but is just asked to sign the binding between key and name, and then the host can use the subject key as a host identity. Regarding elements of procedure, it seemed to me that it would be in scope to specify how to ask the end host to provide a CERT, plus how to handle failure cases (e.g. "I don't recognize the CA", "Bad certificate signature", etc.). In addition, I agree with David's comment that a HIP-aware middlebox ought to be able to challenge a host to provide a CERT. I don't know whether just a generic challenge would be needed, or whether the middlebox would be able to identify the CAs that it recognizes in the challenge.

Sounds like hip-service-00 :)

- Is SPKI the right choice for the default format?
Do we need a default for this? What does it mean that "All implementations MUST support the X.509v3 format." This is an optional, non-critical parameter. It seems to me that implementations ought to be RECOMMENDED to support one or both formats, and we specify what happens when one side of the exchange does not understand CERT at all, or when it understands CERT but does not support the Type number.

It was supposed to be like: If you implement this non-critical parameter you should at-least implement support for this certificate. But I can see your point and I am leaning towards it and here I should refer to the hip-service-00 again.

If needed we can flesh out the certificate handling in the hip-service draft to support the hip-cert draft. So far, the hip-service-00 draft was discussed in the RG. Should we expand this to the WG and process hip-cert and hip-service as a bundle?

BR,
Tobias




- Are the hash and URL encodings needed? At least with on-path
middleboxes they are problematic.
I think the hash and URL encodings are important and would
even like to see them expanded to include http URL,
Distinguished Name, and LDAP path.
Agree.

Looking into this and agreeing.

- Are the examples in the appendixes sufficient?
It would be nice to see an example with sending a certificate chain.
Agree (a non-self-signed example).

OK. can be done.

A few small editorial comments are that in section 2, the capitalization is not consistent in paragraph 3, and it seems like the last sentence before the figure should be the lead sentence of paragraph three, so the reader doesn't infer from the existing paragraph three lead sentence that any HIP packet (e.g. I1) carries CERT.

OK, will fix this.

Regards,
Tom

Thanks for the helpful comments.

--
BR,
Samu

"Programmer is an organism that changes caffeine into code"
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Dipl.-Inform. Tobias Heer, Ph.D. Student
Distributed Systems Group
RWTH Aachen University, Germany
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