Re: [quicwg/base-drafts] QUIC Version Ossification (#2496)

Kazuho Oku <> Wed, 22 May 2019 14:14 UTC

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Date: Wed, 22 May 2019 14:14:32 +0000
From: Kazuho Oku <>
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Subject: Re: [quicwg/base-drafts] QUIC Version Ossification (#2496)
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If we are to remove the version number field in favor of trial decryption, we need to figure out how a server would figure out a packet that failed to decrypt was a connection establishment attempt, so that  it can send a Version Negotiation packet. Otherwise, a client would no longer be possible to fallback to a different version.

One way of resolving the problem is to use the QUIC bit as a SYN bit. If the server fails to trial-decrypt the packet in any of the versions it supports, the server would send a Version Negotiation packet.

Having a SYN bit also helps the server, because trial decryption would only be required for packets that have the flag set.

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