[TLS] Banning implicit CIDs in DTLS

Christopher Wood <caw@heapingbits.net> Thu, 21 May 2020 15:59 UTC

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Date: Thu, 21 May 2020 08:58:35 -0700
From: "Christopher Wood" <caw@heapingbits.net>
To: "TLS@ietf.org" <TLS@ietf.org>
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Subject: [TLS] Banning implicit CIDs in DTLS
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PR #148 in the DTLS 1.3 draft (https://github.com/tlswg/dtls13-spec/pull/148) proposes banning implicit CIDs. This comes at an obvious cost in terms of bytes on the wire. However, in discussions on a parallel thread [1 and related], it's noted that this removes header malleability. 

Given that we don't have backing analysis suggesting that malleability (with the other AAD properties) is safe*, the chairs propose merging this PR as-is. To that end, please respond to the list by May 28, 2020, indicating whether or not you support this PR.

Thanks,
Chris, on behalf of the chairs

*One proposal to address this is by extending the AAD to include the pseudo-header. However, the chairs feel this is an unnecessary divergence from QUIC.

[1] https://mailarchive.ietf.org/arch/msg/tls/kFnlBW-TmlArcU0lD9UQdf_1t_o/