Re: [Unbearable] HTTPS Token Binding with TLS Terminating Reverse Proxies

Piotr Sikora <> Mon, 17 July 2017 10:37 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id C78741318A3 for <>; Mon, 17 Jul 2017 03:37:59 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.001
X-Spam-Status: No, score=-2.001 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RP_MATCHES_RCVD=-0.001, SPF_PASS=-0.001, URIBL_BLOCKED=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 kFXGmmPJKcO6 for <>; Mon, 17 Jul 2017 03:37:58 -0700 (PDT)
Received: from ( [IPv6:2607:f8b0:400c:c08::230]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 437A3131893 for <>; Mon, 17 Jul 2017 03:37:58 -0700 (PDT)
Received: by with SMTP id 35so42739857uax.3 for <>; Mon, 17 Jul 2017 03:37:58 -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=lnl0zYooVTeRKyor0TJg4P82xZNeBJwTQdOpqsirRCk=; b=ZeiYbMBZeNq2wJcyTon46eBq1anGUsLAmnnNRM4dB7nFnRNQMNPzrxEp2Tff+Gm/l0 JwkcXGs0a7aSG84Bywy+B09L0LM9R0CD8bE7lh7Z3MWmkGr4XagBOaUJavYt57zJKu14 VKuiB2SABBRlH4oVypShuffxrKTUb4/9UGbgs9nV8TJp3I/CcNXOn3dKWNcSFGb3T7QD mjF71M3epUT9K3hvE2oc+Qje5oGi+aJEWdWAQAnWtgOuwzEYpl6x6BVKlQOkCPiVmJSs CgOx+dKr84tZWjd1x5mKTXAfYMfRc9WDMH1K/OfIqLW8MPrGMs0ZB3sr68nwGAR+ud0l xGOg==
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=lnl0zYooVTeRKyor0TJg4P82xZNeBJwTQdOpqsirRCk=; b=U58xhR6bmGMwZkbeuLOowxPwwAuUItQCXwvDeTauVVsiVg0xzG8CX2wq7RC25phqMH x+ZQO+SQlljotjMYNBtvJoR3RZ4JBcqbeu1EvyRTLv2aXsN9QX+al+T7VX8fgp/qrFCO s7rKlZtEq99V9Ki5BPDSbSStf6ynGK91i8+CnEBa7hxvw8DfxGkqPf/ch8LA2MmNZ537 CQWiVJRgReCn9c+kN9s/iLUzw2vfbjbHXpwFlmEXU363KqewYv+ronBtm+2bh82WaMh+ uvYNcQz4FC8h266KUdrO5clq3FmkWbASal0bRcvHBv4iCoRkWfTYn2nCq0d7NBL6v0xO SqkQ==
X-Gm-Message-State: AIVw112FQPJUu4nAWfGgfggcq5U/XbEYkDKMxnk268TNVICUmw+fwf5t DfBrvt7GiGz83fwBRSaID6WoOpO+kVLh
X-Received: by with SMTP id b71mr1087818vka.18.1500287877037; Mon, 17 Jul 2017 03:37:57 -0700 (PDT)
MIME-Version: 1.0
Received: by with HTTP; Mon, 17 Jul 2017 03:37:56 -0700 (PDT)
In-Reply-To: <>
References: <>
From: Piotr Sikora <>
Date: Mon, 17 Jul 2017 12:37:56 +0200
Message-ID: <>
To: Brian Campbell <>
Cc: IETF Tokbind WG <>
Content-Type: text/plain; charset="UTF-8"
Archived-At: <>
Subject: Re: [Unbearable] HTTPS Token Binding with TLS Terminating Reverse Proxies
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: "\"This list is for discussion of proposals for doing better than bearer tokens \(e.g. HTTP cookies, OAuth tokens etc.\) for web applications. The specific goal is chartering a WG focused on preventing security token export and replay attacks.\"" <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Mon, 17 Jul 2017 10:38:00 -0000

Hey Brian,
looks good, thanks for working on that!

One question:

>   Reverse proxies SHOULD only add the headers to requests that are
>   forwarded to trusted backend servers.

Why? What's the attack vector, security and/or privacy implications here?

Best regards,
Piotr Sikora

On Fri, Jul 14, 2017 at 6:59 PM, Brian Campbell
<> wrote:
> Just a not-so-subtle reminder that HTTPS Token Binding with TLS Terminating
> Reverse Proxies is one of the agenda items for Monday's meeting in Prague
> and it would be great if there was some familiarity with it going into the
> meeting. It's relativity short as drafts go, if you're looking for something
> to read en route to the meeting:
> CONFIDENTIALITY NOTICE: This email may contain confidential and privileged
> material for the sole use of the intended recipient(s). Any review, use,
> distribution or disclosure by others is strictly prohibited.  If you have
> received this communication in error, please notify the sender immediately
> by e-mail and delete the message and any file attachments from your
> computer. Thank you.
> _______________________________________________
> Unbearable mailing list