On Wed, Mar 24, 2021 at 7:18 PM John Scudder via Datatracker < nore...@ietf.org> wrote:
> John Scudder has entered the following ballot position for > draft-ietf-tls-dtls13-41: Discuss > > When responding, please keep the subject line intact and reply to all > email addresses included in the To and CC lines. (Feel free to cut this > introductory paragraph, however.) > > > Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html > for more information about IESG DISCUSS and COMMENT positions. > > > The document, along with other ballot positions, can be found here: > https://datatracker.ietf.org/doc/draft-ietf-tls-dtls13/ > > > > ---------------------------------------------------------------------- > DISCUSS: > ---------------------------------------------------------------------- > > Section 4.5.2: > > Implementations which choose to generate an alert instead, MUST > generate error alerts to avoid attacks where the attacker repeatedly > probes the implementation to see how it responds to various types of > error. Note that if DTLS is run over UDP, then any implementation > > I just don’t understand this, despite having hopped over to RFC 8446 > Sections 6 > and 6.2. Is the intention that “error alert” implies closure of the > association? That doesn’t seem to be exactly what 8446 says — it says the > receiver of the alert closes the connection, but it doesn’t mandate this > for > the sender (except in the case of “fatal alert” messages, where “fatal” > seems > like the exception that proves the rule). > > It may be that “everyone knows” an error alert is the same as termination, > but > it’s not obvious in the plain English of the text I reviewed. Or maybe I’m > barking up the wrong tree and this isn't what the text quoted above is even > driving at. > You're right. This should say "fatal alert". https://github.com/tlswg/dtls13-spec/pull/219 -Ekr > > ---------------------------------------------------------------------- > COMMENT: > ---------------------------------------------------------------------- > > Thanks for the well-written document. In particular I thought it was > helpful > that you noted important divergences from DTLS 1.2 in line and not just at > the > end. > > COMMENTS: > > Section 3.1: > > I found the explanatory text to be confusing. You start with a figure > illustrating a lost HelloRetryRequest. Then you tell me the server > maintains a > rexmit timer: > > The server also maintains a retransmission timer and retransmits when > that timer expires. > > But then you immediately tell me that it actually doesn’t: > > Note that timeout and retransmission do not apply to the > HelloRetryRequest since this would require creating state on the > server. The HelloRetryRequest is designed to be small enough that it > will not itself be fragmented, thus avoiding concerns about > interleaving multiple HelloRetryRequests. > > I presume that if I added some more words to this, your intent is that the > server maintains a retransmission timer *for messages other than > HelloRetryRequest*. As written, it gave me some whiplash. > > Section 4.2.1: > > In general, > implementations SHOULD discard records from earlier epochs, but if > packet loss causes noticeable problems implementations MAY choose to > retain keying material from previous epochs for up to the default MSL > specified for TCP [RFC0793] to allow for packet reordering. > > It seems to me as though “if packet loss causes noticeable problems” is > saying > either too much, or not enough. Not enough: problems for whom? Noticeable > by > whom? How is this determined? Do you really mean I’m supposed to work this > out > dynamically as the text sort-of implies? Too much: if you’re not going to > answer the foregoing, maybe don’t taunt me, and omit the clause entirely? > Or, > possibly a less vague rewrite could be in the nature of “if providing > service > to an application that is especially sensitive to packet loss”. > > NITS: > > Section 2: > > “The reader is also as to be familiar” s/as/assumed/ > > Section 11: > > Although the cookie must allow the server to produce the right > handshake transcript, they > > “It” not “they” (agreement in number) > > and > > DTLS with connection IDs allow for endpoint addresses to > change during the association; > > “allows” not “allow” (agreement in number) > > > >
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