Subject: [Emu] Comments on draft-mattsson-eap-tls13-01

From: Bernard Aboba <[email-masked]>
Date: Fri, 19 Jan 2018 09:26:11 -0800

Overall, this draft is a significant improvement over the previous one.

However, this draft appears to add support for new authentication modes
such as PSK and ticket authentication. As far as I know, these features are
not supported in any existing implementation
and therefore would complicate testing and advancement of EAP-TLS to
Standards status. I am also concerned that these changes will invalidate
prior EAP-TLS security proofs and introduce new potential security
vulnerabilities.

John Mattsson said:

Hi,

We have submitted an updated version of draft-mattsson-eap-tls13. The
new version is a significant update based on the feedback and comments
on the EAP and EMU mailing lists. The new version also fills in all
the sections that was TDB in the -00 version.

- The draft now updates version updates RFC5216 (instead of
obsoleting) and all text have been updated to make sure that the
update stays compatible with all existing implementations of EAP-TLS.

- Added more text on what TLS 1.3 changes and why an update to RFC5216
is needed.

- As this is now an update, all duplicated text is removed, and the
draft only describe the changes to message flow, messages, key
derivation, privacy, etc. when TLS 1.3 is used.

The new draft follows the structure of RFC5216 and lists updates (if
any) to each section.

- Clearly stated that PSK authentication SHALL not be used (except for
resumption).

[BA] Why add support for PSK authentication outside of resumption? AFAIK there

are no implementations of this.

- Due to the encrypted handshake in TLS 1.3 there is no longer any
need for the EAP client to send and empty certificate list.

A privacy section has been added that explains this.

- A key hierarchy section has been added specifying that when TLS 1.3
is used then Key_Material, IV, and Session-Id

SHALL be derived from the exporter_master_secret using the TLS
exporter interface.

Comments appreciated.

Cheers,
John