Re: [secdir] Secdir last call review of draft-ietf-httpbis-encryption-encoding-08

Martin Thomson <> Wed, 05 April 2017 22:32 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 46E0E127978; Wed, 5 Apr 2017 15:32:52 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.7
X-Spam-Status: No, score=-2.7 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (2048-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id cYW9ZLF2jjCJ; Wed, 5 Apr 2017 15:32:50 -0700 (PDT)
Received: from ( [IPv6:2607:f8b0:400d:c09::232]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 5576A1294C8; Wed, 5 Apr 2017 15:32:43 -0700 (PDT)
Received: by with SMTP id p22so23910614qka.3; Wed, 05 Apr 2017 15:32:43 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=yI0jB5gy9FBC1BAchxJ6qSMnSsEivOs4HzlVE5pTWzE=; b=VnYUbdIc+IGxcNj5F+dfvAka1rmR+h/hrxZNc+PR3TLqylBrA0zWk7HSICaylycrF1 M8O0SEMBDFJN6AqVb92S8qIuRi3jCwmYkyQDkpMJqdkH3PGBDZ7rzKc06XDN3TjIu+UW o8wCpT95U/oVJRY3Bqn2v5pkA7PfgBJRZBCJ0wyh+YXXG8YcP0I7FaXlmnfO/NL9W/al Q5nkEWoGuSqYa485/ixyCpw+JlqdOS2sx/Sctva0dadgEhQDHgGzSDIUsxe+F72/Vbci IDIRgkFlNd4ZNxxVCeuxcHMIotPBzuCB4EK3OfRPAYIeMXS0No1IYOB22XnUqcL80Dfj JOog==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=yI0jB5gy9FBC1BAchxJ6qSMnSsEivOs4HzlVE5pTWzE=; b=XgZrNPLjka/38mL+Ojsa9Kw2A6RtrEqJSXHD6c8c0wj/Xjc8bgV/n2DMWt+7is10YM qV3804+uAOQ0B7mIm5DT2uu9O+fFJ3cPTKpw2MkOISImgV4nPJFHgB15qzpkGa4mznxj Z6kvHO0g8CT8LJznI/Q91QFMxjYHyQF35Cn/7mIZRL5p+uuT/dH7P9+gsCbS4T4OkC0v 6uQSvHcacUxdO5xHDuhq3w86vVN9+usvJiutiL8IyttZ3ZolvQ0/ra8pCm9o7HOYZgZe HInPfS+ELTrXIX2pOaWGZLA10R4Z19WnK1l1eQ3AfutEQexoskh03LEoNjUMK4x00SCy zfTw==
X-Gm-Message-State: AFeK/H3Wzjnvxt2kPTbR6IMYXMtr1eRwufPHXiOVW7pGYO8TuzItf/5m8xSrcJ44ZzOOinjEIL8ziKUA2p/x6w==
X-Received: by with SMTP id d85mr8066225qkc.202.1491431562562; Wed, 05 Apr 2017 15:32:42 -0700 (PDT)
MIME-Version: 1.0
Received: by with HTTP; Wed, 5 Apr 2017 15:32:42 -0700 (PDT)
In-Reply-To: <>
References: <>
From: Martin Thomson <>
Date: Thu, 6 Apr 2017 08:32:42 +1000
Message-ID: <>
To: Robert Sparks <>
Cc: "" <>,, "" <>, HTTP Working Group <>
Content-Type: text/plain; charset=UTF-8
Archived-At: <>
Subject: Re: [secdir] Secdir last call review of draft-ietf-httpbis-encryption-encoding-08
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: Security Area Directorate <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Wed, 05 Apr 2017 22:32:52 -0000

On 6 April 2017 at 06:47, Robert Sparks <> wrote:
> My only concern is that the document suggests it would be ok to use a
> counter to provide a unique salt value
> for each message. I suspect that provides the kind of information leak
> the draft discusses avoiding.

Hi Robert, can you explain what sort of leakage you are concerned
about?  I mean, I can understand how you could construct the sequence
of resources that were encrypted using a counter for the salt, but I
don't know what that might imply.

That said, I think that the counter thing can be removed.  We require
128 bits of salt, which is a space that is large enough to select
randomly from in perpetuity.