Re: [Taps] I-D Action: draft-ietf-taps-transport-security-03.txt

[Theresa Enghardt <[e-mail]>]

Dear TAPS,

having shepherded the minset draft, and, in the process, having seen a
lot of discussion around security, where we mostly pointed to the
security survey draft, I gave this draft another read in the current
version, with a focus on Section 5.

Thanks for the update, this document was a good read.

However, I have some comments, which I'm sharing now rather than later,
just in case there's anything which is better discussed in-person in
Bangkok.


Right now, the abstract states that this document is a survey of
security protocols. I suggest to add text saying that the document also
provides a minimal set of security features. Essentially, this document
and minset together cover the "minimum requirements of a secure
transport system".


In Section 5, the document groups security features into mandatory and
optional features, and states their transport dependency and application
dependency. Application dependency, for me, relates to whether a feature
is "functional", "optimizing", or "automatable" (in minset terminology).
For example, if there is no application dependency, the feature is
"automatable" and does not have to be exposed to the application. In
contrast, a "function" feature needs to be exposed to the application.

In Section 5.1, I am missing transport dependency and application
dependency for the mandatory transport features. For example, I would be
interested to know what is the minimum that the transport system needs
to expose to the application for public-key based authentication?

In Section 5.1, what is "unilateral responder authentication", which I
haven't found in other places in the document under this name?

In Section 5.2, "Session caching and management" has no application
dependency. However, later in Section 6.1, we do expose Session Cache
Management to the application. My interpretation is that this is just an
"optimizing" feature, which is why there is no application dependency,
but it is still useful to expose. It might help to make this explicit in
the text.

In Section 5, do we want to mention any security features related to
integrity protection?


As far as I can see, none of the protocols we survey provide any
features explicitly providing privacy. Maybe this is worth highlighting
in the Security considerations section, beyond saying that no claims of
privacy properties are made.


Finally, I would be in favor of asking for a Secdir early review to make
sure we're not missing anything in the survey.


Thank you again for this draft. I really appreciate that we're
discussing transport security features in this way.


Best,
Theresa