Re: [quicwg/base-drafts] Authenticating connection IDs (#3439)

Marten Seemann <> Thu, 05 March 2020 02:52 UTC

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Date: Wed, 04 Mar 2020 18:52:21 -0800
From: Marten Seemann <>
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Subject: Re: [quicwg/base-drafts] Authenticating connection IDs (#3439)
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I'm not convinced that we need a transport parameter here. As explained by @martinthomson, a transport parameter would only protect the connection IDs used after the Retry, i.e. CIDs that are used *after* a connection has been accepted and an endpoint has created state for this connection.

At this point, we could require endpoints to keep track of the SCID that they used, and discard incoming packets that arrive at this connection where the DCID doesn't match the SCID they chose. If I'm not mistaken, this would thwart the attack (and as a bonus, it would do so earlier than the TP proposed here, since the TP would only be validated after the handshake completes).

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