Re: [quicwg/base-drafts] Rework Key Update (#2237)

Martin Thomson <notifications@github.com> Fri, 21 December 2018 05:56 UTC

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Subject: Re: [quicwg/base-drafts] Rework Key Update (#2237)
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martinthomson commented on this pull request.



> +
+Endpoints maintain separate read and write secrets for packet protection.  An
+endpoint initiates a key update by updating its packet protection write secret
+and using that to protect new packets.  The endpoint creates a new write secret
+from the existing write secret as performed in Section 7.2 of {{!TLS13}}.  This
+uses the KDF function provided by TLS with a label of "quic ku".  The
+corresponding key and IV are created from that secret as defined in
+{{protection-keys}}.  The header protection key is not updated.
+
+The endpoint uses the key and IV to protect all subsequent packets, and inverts
+the value of the KEY_PHASE bit to signal the change of keys.
+
+An endpoint MUST NOT initiate more than one key update at a time.  A new key
+cannot be used until the endpoint has received an acknowledgment for a packet it
+sends with the new keys.  An endpoint that receives a packet protected with old
+keys that includes an acknowledgement for a packet protected with newer keys MAY

No, the point of this is that you requested a key update and the peer didn't comply.  This is how we ensure that endpoints update when requested.

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