[Taps] Roman Danyliw's Abstain on draft-ietf-taps-interface-24: (with COMMENT)

[Roman Danyliw via Datatracker <[e-mail]>]

Roman Danyliw has entered the following ballot position for
draft-ietf-taps-interface-24: Abstain

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COMMENT:
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Thank you to Sean Turner for the SECDIR review.

Thank you for the iteration on my DISCUSS position and the efforts to refine
the document in response.  I want to acknowledge the significant effort
required to produce https://github.com/ietf-tapswg/api-drafts/pull/1463.  My
recommendation would be to merge it as it improves -24.

I am abstaining on this document because there is a degree of specificity in
the abstract API in this document that I cannot reconcile with proposed
standard status.  I would expect to be able to do some basic, repeatable degree
of conformance evaluation to understand if a concrete API meets what is
described in this abstract API – put more simply, how would I know I have an
“API to Transport Services”. Focusing just on the security aspects of the API,
I struggled to envision how to do that.

To summarize my DISCUSS feedback, it isn’t clear which classes of security
parameters require concrete implementation from the abstract API.

The subsequent PR improved the editorial presentation (much appreciated!), but
the following text created further ambiguity:

   The set of security parameters defined here is not exhaustive, but
   illustrative. Implementations SHOULD expose an equivalent to the parameters
   listed below to allow for sufficient configuration of security parameters,
   but the details are expected to vary based on platform and implementation
   constraints.

If this text and parameters are “illustrative”, they are examples.  What
conformance is required for the concrete security API if only examples are
provided?  How does one unambiguously agree on equivalence relative to examples?

If “implementations SHOULD expose”, that means that they can choose not to and
still be conformant which degenerates into very little normative guidance
around the security aspects of the API.

==[ DISCUSS feedback on -24 ]==
Thanks for the revised text in v-22, -23 and -24.  I’m still do not
understanding what exact Security Parameters that Section 6.3.1 is normatively
specifying (and which of them are examples).  My confusion is that Section 6.2
has a crisp list of parameters with an explicit names, type, and default value.
 The equivalent is not present for the security related parameters.

Section 6.3 says “except as noted below, as with the rest of the Transport
Services API, exact names of parameters and/or values of enumerations (e.g.,
ciphersuites) used in the security parameters are system and implementation
specific, and ought to be chosen to follow the principle of least surprise for
users of the platform / language environment in question.”  How does one read
“except when noted below”?  Is this section saying the normative parameters are
server-certificate, client-certificate, pinned-server-certificate, alpn,
supported-group, ciphersuite, signature-algorithm, max-cached-sessions,
cached-session-lifetime-seconds, pre-shared-key OR that “an API should define
certificate bundles, certificate chains for pinned certificates, ALPN, session
cache management parameters, supported groups/ciphersuite/ parameters, and PSK
parameters but no further details are provided here beyond naming these
categories of parameters”?

I observe that the guidance in Section 4.1 suggests that parameter names are in
CamelCase.  That isn’t used here (e.g., “server-certificate” should be
“ServerCertificate”).  This might hint that there are not parameters here. 
However, the bulleted list in Section 6.3.1. is prefaced with “Security
configuration parameters and sample usage follow:” seems to suggest that these
are concrete parameters. ==[ DISCUSS ]==