Re: [quicwg/base-drafts] Rewrite key update section (#3050)

Jana Iyengar <notifications@github.com> Fri, 01 November 2019 04:06 UTC

Return-Path: <noreply@github.com>
X-Original-To: quic-issues@ietfa.amsl.com
Delivered-To: quic-issues@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 585881200C5 for <quic-issues@ietfa.amsl.com>; Thu, 31 Oct 2019 21:06:34 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -8
X-Spam-Level:
X-Spam-Status: No, score=-8 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=0.001, MAILING_LIST_MULTI=-1, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=github.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id nqMIQ3JMyZ-g for <quic-issues@ietfa.amsl.com>; Thu, 31 Oct 2019 21:06:32 -0700 (PDT)
Received: from out-24.smtp.github.com (out-24.smtp.github.com [192.30.252.207]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 0AA3712006D for <quic-issues@ietf.org>; Thu, 31 Oct 2019 21:06:32 -0700 (PDT)
Received: from github-lowworker-45eca55.ac4-iad.github.net (github-lowworker-45eca55.ac4-iad.github.net [10.52.25.70]) by smtp.github.com (Postfix) with ESMTP id 5897A6A0BE9 for <quic-issues@ietf.org>; Thu, 31 Oct 2019 21:06:31 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=github.com; s=pf2014; t=1572581191; bh=V3c+Wp8qq3ufJ+VT0LqAjmvdJGqIVXNsUjSMZhKCnuo=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=TuDWKXEbutK5y3T6/WsBkemE28RE/Ksvl0W2q5Mqy0oBn7XrjxcL3L7mJqfRRO+Tr cZygdu3102w+GRXACkyYHFD6t6+wluN+Xsra32Q1Bj1Vu/XGA5WhSe/y27MiQz6RDB axBH1fAfyOIeoa/FzgMdp7hK4iUjZK7POuJO6FXo=
Date: Thu, 31 Oct 2019 21:06:31 -0700
From: Jana Iyengar <notifications@github.com>
Reply-To: quicwg/base-drafts <reply+AFTOJKYJPJPIYUKAJJBHNIV3ZDX5PEVBNHHB3CL6HQ@reply.github.com>
To: quicwg/base-drafts <base-drafts@noreply.github.com>
Cc: Subscribed <subscribed@noreply.github.com>
Message-ID: <quicwg/base-drafts/pull/3050/review/310283028@github.com>
In-Reply-To: <quicwg/base-drafts/pull/3050@github.com>
References: <quicwg/base-drafts/pull/3050@github.com>
Subject: Re: [quicwg/base-drafts] Rewrite key update section (#3050)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5dbbaf4749f8e_7e583f820e8cd960487262"; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: list
X-GitHub-Sender: janaiyengar
X-GitHub-Recipient: quic-issues
X-GitHub-Reason: subscribed
X-Auto-Response-Suppress: All
X-GitHub-Recipient-Address: quic-issues@ietf.org
Archived-At: <https://mailarchive.ietf.org/arch/msg/quic-issues/9NhQaiRbBFHbDrhsVoydU2xHcyQ>
X-BeenThere: quic-issues@ietf.org
X-Mailman-Version: 2.1.29
List-Id: Notification list for GitHub issues related to the QUIC WG <quic-issues.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/quic-issues>, <mailto:quic-issues-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/quic-issues/>
List-Post: <mailto:quic-issues@ietf.org>
List-Help: <mailto:quic-issues-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/quic-issues>, <mailto:quic-issues-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 01 Nov 2019 04:06:34 -0000

janaiyengar approved this pull request.

A few nits. I've asked @kazuho if he could take another look as well.

> +corresponding key and IV are created from that secret as defined in
+{{protection-keys}}.  The header protection key is not updated.
+
+For example, to update write keys with TLS 1.3, HKDF-Expand-Label is used as:
+
+~~~
+secret_<n+1> = HKDF-Expand-Label(secret_<n>, "quic ku",
+                                 "", Hash.length)
+~~~
+
+The endpoint toggles the value of the Key Phase bit and uses the updated key and
+IV to protect all subsequent packets.
+
+An endpoint MUST NOT initiate a key update prior to having received an
+acknowledgment for a packet that it sent protected with keys from the current
+key phase.  This ensures that keys are available to both peers before another

```suggestion
key phase.  This ensures that keys are available to both peers before another key update
```

> +receiving packets.  These keys will be needed to process packets the peer sends
+after updating.
+
+An endpoint SHOULD retain old keys so that packets sent by its peer prior to
+receiving the key update can be processed.  Discarding old keys too early can
+cause delayed packets to be discarded.  Discarding packets will be interpreted
+as packet loss by the peer and could adversely affect performance.
+
+
+## Responding to a Key Update
+
+A peer is permitted to initiate a key update after receiving an acknowledgement
+of a packet in the current key phase.  If a packet is received with a key phase
+that differs from the value the endpoint used to protect the last packet it
+sent, the endpoint uses the next packet protection keys for reading and the
+corresponding key and IV; see {{receive-key-generation}} for considerations

It might be kinder to the reader if you could split this 3-line sentence into two sentences.

> +its peer has updated keys twice without awaiting confirmation.  An endpoint MAY
+treat consecutive key updates as a connection error of type KEY_UPDATE_ERROR.
+
+An endpoint that receives an acknowledgement that is carried in a packet
+protected with old keys where any acknowledged packet was protected with newer
+keys MAY treat that as a connection error of type KEY_UPDATE_ERROR.  This
+indicates that a peer has received and acknowledged a packet that initiates a
+key update, but has not updated keys in response.
+
+
+## Timing of Receive Key Generation {#receive-key-generation}
+
+Endpoints responding to an apparent key update MUST NOT generate a timing
+side-channel signal that might indicate that the Key Phase bit was invalid (see
+{{header-protect-analysis}}).  Endpoints can use dummy packet protection keys in
+place of discarded keys when key updates are not yet permitted; using dummy keys

```suggestion
place of discarded keys when key updates are not yet permitted. Using dummy keys
```

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/quicwg/base-drafts/pull/3050#pullrequestreview-310283028