Re: [quicwg/base-drafts] Authenticate connection IDs (#3499)

Martin Thomson <notifications@github.com> Mon, 11 May 2020 22:56 UTC

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Date: Mon, 11 May 2020 15:56:51 -0700
From: Martin Thomson <notifications@github.com>
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Subject: Re: [quicwg/base-drafts] Authenticate connection IDs (#3499)
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@martinduke, if the attacker modifies the SCID in an Initial that ultimately causes a Retry to be sent, that doesn't affect the final state in any way, so there is no harm done.

The reason we authenticate the DCID on that packet in the way we do is to verify that the the server is cooperating with the entity that generated the Retry token.  Also, the client-chosen DCID value might persist as the server could use that value to determine its choice of connection ID.  The client can't change its mind, so authenticating a single value is enough.

That said, I will take on advisement that we don't require that the client doesn't change its connection ID.  Issue inbound.

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