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Re: [TLS] [OPSEC] Call For Adoption: draft-wang-opsec-tls-proxy-bp

Eric Rescorla <ekr@rtfm.com> Wed, 29 July 2020 23:57 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Wed, 29 Jul 2020 16:56:39 -0700
Message-ID: <CABcZeBNyFBaHfKf5JGXb7BBc+pcwkLoSx2wYA63AZs0O-WRtug@mail.gmail.com>
To: Stephen Farrell <stephen.farrell@cs.tcd.ie>
Cc: "Eric Wang (ejwang)" <ejwang=40cisco.com@dmarc.ietf.org>, Nick Harper <nharper=40google.com@dmarc.ietf.org>, Ron Bonica <rbonica@juniper.net>, OPSEC <opsec@ietf.org>, "tls@ietf.org" <tls@ietf.org>
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Subject: Re: [TLS] [OPSEC] Call For Adoption: draft-wang-opsec-tls-proxy-bp
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On Wed, Jul 29, 2020 at 4:27 PM Stephen Farrell <stephen.farrell@cs.tcd.ie>
wrote:

>
> Hiya,
>
> On 29/07/2020 23:46, Eric Wang (ejwang) wrote:
> > It was the motivation of this draft to help reduce/prevent
> > non-compliance, as mentioned earlier.
> TLS MITM products, by design, do not comply with the TLS
> protocol, which is a 2 party protocol.
>

Without taking a position on this document, I do not believe this statement
to be correct.

1. TLS doesn't document at all how the server is validated, so from a
technical perspective a MITM proxy is simply a TLS server with a
certificate issued by a locally installed CA attached to a TLS client that
connects to the server (what is known in SIP as a B2BUA).
2. TLS 1.3 specifically documents invariants for TLS terminating
middleboxes, including MITM proxies (
https://tools.ietf.org/rfcmarkup?doc=8446#section-9.3).
3. Ignoring MITM proxies, TLS is widely deployed in operating
configurations where the client connects to a TLS reverse proxy (i.e., a
CDN) which then connects to the server; this is also not a two-party
situation.

What text in TLS do you believe terminating proxies (in either direction)
do not conform to?

-Ekr

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