[Lurk] review of draft-cairns-tls-session-key-interface-01

["Fossati, Thomas (Nokia - GB)" <[e-mail]>]

Hi guys,

I've just finished reading your draft.  There's plenty of information &
references in it, thank you.

A few comments below:

- The way the RSA interface is defined at the moment suffers from the
"decryption oracle syndrome".  We should really try to avoid this and let
the LURK box produce the MS instead -- as you're also hinting in the
DISCUSSION para of Section 5.1.1.

- LURK has use cases that need high throughput: we really want to be able
to fill the pipe between the Edge and Key Server, and also treat each
transaction independently.  That's why a UDP based protocol is attractive,
vs. for example a HTTP2/TCP based one, which would incur HOL on packet
loss.  Also an efficient encoding like the CBOR/CoAP that you are
proposing looks really great to keep the overhead at a minimum.  I've
never used CoAP in high throughput applications though (quite the
opposite, really), so I'm not sure whether its default congestion control
algorithm is OK for this scenario?  Have you done any experiment?

- It's too early to nit-pick on the wire format, I know, but I'd be nice
to have an explicit transaction id in the LURK payloads so that the Edge
Server can correlate the TLS handshake with the specific LURK transaction
(for logging/debugging/analysis purposes).

- The same comments I sent for draft-erb-lurk-rsalg yesterday about the
lack of "LURK box capability" and "Cert/key rotation" interfaces.

Happy to discuss this further f2f.

Cheers, t