Re: [quicwg/base-drafts] unrecoverable loss pattern leads to deadlock (#2863)

Kazuho Oku <notifications@github.com> Fri, 18 October 2019 07:04 UTC

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Date: Fri, 18 Oct 2019 00:04:04 -0700
From: Kazuho Oku <notifications@github.com>
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Subject: Re: [quicwg/base-drafts] unrecoverable loss pattern leads to deadlock (#2863)
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Regarding the way on discarding the Handshake keys, I think the failures the WG have made until now are that we have been looking for a clever method in trying to *infer* when a Handshake key can be dropped, and/or using 1-RTT packet to tell the peer that the peer can drop the handshake keys (the problem here is that the peer might continue retransmitting Handshake packets if the endpoint ceases to send 1-RTT packets). Based on the discussion in Cupertino, I think that if we are to drop the Handshake keys, we should adopt a safer approach.

I'd argue that there exists a class of approaches that can be considered safe. That is to require an endpoint to retain the Handshake keys until the peer sends an explicit signal instructing the endpoint to drop the Handshake keys. Assuming that my observation in [the comment right above](https://github.com/quicwg/base-drafts/issues/2863#issuecomment-543540677) is correct, we'd also need to adjust the transition to the handshake confirmed state to when an endpoint sends and receives that message.

That signal can be a new frame, a header bit, or a KeyUpdate.

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