Re: [6tisch-security] EALS and how to go from 6tisch-minimal-security to zero-touch enrollment

[Michael Richardson <[e-mail]>]

Göran Selander <[e-mail]> wrote:
    >> In order for the pledge to be passive, and the JRC to manage the bulk
    >> (certificates and vouchers take a dozen fraglets, sadly), I would like
    >> the zero-touch process to be driven by the JRC.

...

    >> EALS also proposes to move the voucher nonce and ownership voucher
    >> into the protocol itself, eliminating the provisional state, and
    >> ownership voucher.
    >>
    >> This moves the entire exchange control back to the JRC.  No CoMI
    >> interface would be needed for communicating the voucher.
    >>
    >> EALS suggests that the enrollment occur over CoAP, driven by the
    >> pledge.

    > Actually, we mention that the EDHOC protocol may be reversed, and it
    > may be driven by the JRC, but first authenticating the pledge enables
    > the authorization step to come earlier.

Yes, EDHOC is reversed, and so the JRC can control when each pledge enrolls.
The JRC would not initiate a message_1 until it is ready for that pledge to
enroll.   Once it has received message_2, the JRC will know securely exactly
who is trying to connect, and if it still has concerns, or there just isn't
network bandwidth yet, it could delay sending message_3 until it is ready.

What we need to do is figure out is how the JRC inserted delays might affect
retransmission timers.  I think that the messages are all CoAP transactions
initiated from the EDHOC initiator.

Actually, that brings up a question:

>  +--------------------------------------->|    Third party
>  |                                        | < - - - - - - - - >
>  |  EDHOC message_3 (EXT_3 = Authz info)  |    authorization
>  |<---------------------------------------+

how does the initatior know that message_3 arrived okay?
I seem to be missing an ACK for this message.


--
Michael Richardson <[e-mail]>, Sandelman Software Works
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