Re: [quicwg/base-drafts] describe how 0-RTT is accepted and rejected (#2841)

Marten Seemann <notifications@github.com> Wed, 26 June 2019 02:10 UTC

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Subject: Re: [quicwg/base-drafts] describe how 0-RTT is accepted and rejected (#2841)
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marten-seemann commented on this pull request.



>  
-A server rejects 0-RTT by rejecting 0-RTT at the TLS layer.  This also prevents
-QUIC from sending 0-RTT data. A server will always reject 0-RTT if it sends a
-TLS HelloRetryRequest.
+A server rejects 0-RTT by sending a ServerHello without the EarlyDataIndication.
+A server will always reject 0-RTT if it sends a TLS HelloRetryRequest.  When
+rejecting 0-RTT, a server MUST NOT process any 0-RTT packets, even if it is in
+possesion of the keys to do so.  When 0-RTT was rejected, a client MUST treat
+receipt of an acknowledgement for a 0-RTT packet as a connection error of type

@kazuho Of course you **can** skip packet numbers, since this is indistinguishable from packet loss.
The text you're quoting is about the optimistic ACK attack, and describes a mechanism how you skip a single packet number from time to time **in order to detect this attack**. It is not intended to start a packet number space at a much higher packet number. Furthermore, if I understand your point here correctly, what you actually want to do is **not** to perform the check if a skipped packet number is acknowledged, so you really can't use this text as a justification...

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