Re: [secdir] secdir review of draft-ietf-6tisch-architecture-21

[Michael Richardson <[e-mail]>]

Pascal Thubert (pthubert) <[e-mail]> wrote:
    >> - retransmit a previous message by destroying an ack. It results and
    >> + retransmit a previous message by destroying an ack. If this results an
    >> > upper layer protocol must provide a way to detect replayed messages and
    >> > cope with them.
    >>

    > Sorry I cannot parse the resulting sentence with your proposal.
    > My mistake was only and -> an but I'm sure that the sentence can be better written.
    > I changed to
    > "

    > This authentication steps must be such that they cannot be replayed by an
    > attacker, and it must not depend on the tentative ASN being valid. Note that
    > IEEE std. 802.15.4 TSCH does not provide replay protection at all, and that
    > an ack may be lost, which can cause a legitimate node to retransmit a frame.
    > Upper layer protocols must thus provide a way to detect duplicates and cope
    > with them.

    > "

Good, I like it fine.

    > Proposed new text:
    > "
    > At that point, an additional step may be required to ensure that the ASN is
    > correct. If the ASN is not guaranteed to be correct by other means, the
    > pledge should perform a first exchange with a peer node that is trusted and
    > has already joined, e.g., its RPL time parent, and the message should not be
    > encrypted but only authenticated at the Link-Layer.
    > The request from the pledge should contain a nonce with a random part that
    > is not ASN, and the authenticated response should contain the current ASN
    > and echo the nonce.
    > "

okay. Tero?

--
Michael Richardson <[e-mail]>, Sandelman Software Works
 -= IPv6 IoT consulting =-