[TLS] Genart last call review of draft-ietf-tls-ecdhe-psk-aead-03

Dan Romascanu <dromasca@gmail.com> Mon, 15 May 2017 10:46 UTC

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Date: Mon, 15 May 2017 03:46:35 -0700
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Subject: [TLS] Genart last call review of draft-ietf-tls-ecdhe-psk-aead-03
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Reviewer: Dan Romascanu
Review result: Ready with Issues

I am the assigned Gen-ART reviewer for this draft. The General Area
Review Team (Gen-ART) reviews all IETF documents being processed
by the IESG for the IETF Chair.  Please treat these comments just
like any other last call comments.

For more information, please see the FAQ at

<https://trac.ietf.org/trac/gen/wiki/GenArtfaq>.

Document: draft-ietf-tls-ecdhe-psk-aead-??
Reviewer: Dan Romascanu
Review Date: 2017-05-15
IETF LC End Date: 2017-05-18
IESG Telechat date: 2017-05-25

Summary:

This is a straight-forward and clear document that defines several new
cipher suites for the Transport Layer Security (TLS) protocol version
1.2 and higher, based on the Ephemeral Elliptic Curve Diffie-Hellman
with Pre-Shared Key (ECDHE_PSK) key exchange together with the
Authenticated Encryption with Associated Data (AEAD) algorithms
AES-GCM and AES-CCM. The document is well written and I appreciate the
effort to clarify in the Introduction the context, what was missing,
and why the document is necessary. The document is Ready, there is one
issue about support for TLS version 1.3 and higher that may need some
text clarification. 

Major issues:

Minor issues:

Section 4 ('Applicable TLS Versions') describes in details how the
cipher suites defined in the document make use of the authenticated
encryption with additional data (AEAD) defined in TLS 1.2 [RFC5246]
and DTLS 1.2 [RFC6347]. About TLS 1.3 it just says: 

' TLS 1.3 and above version, negotiate and support these cipher suites
in a different way.'

This may raise some concerns as 'in a different way' is ambiguous,
especially compared to the details included for TLS 1.2. Moreover, TLS
1.3 is still work-in-progress, and I believe that this document when
approved needs to wait for TLS 1.3 to be approved for publication.
Will anything change, or need to be added? Some better clarification
text would help IMO. 

Nits/editorial comments: