Re: [pkix] How do we differentiate authentic servers from proxies performing TLS interception?

Jeffrey Walton <> Thu, 12 November 2015 13:09 UTC

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Date: Thu, 12 Nov 2015 08:09:08 -0500
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From: Jeffrey Walton <>
To: "Miller, Timothy J." <>
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Subject: Re: [pkix] How do we differentiate authentic servers from proxies performing TLS interception?
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On Thu, Nov 12, 2015 at 8:00 AM, Miller, Timothy J. <> wrote:
>> How do we differentiate authentic servers from proxies performing TLS
>> interception?
> What would be the point?  You're going to accept a legitimate MitM (e.g., corporate security) and a malicious MitM won't use the extension.

Actually, I don't. I fail the connection. But I understand your point,
and many folks chose to be intercepted so the ad can get through...

> It's more productive to attack the problem of binding *authorities* to sites--e.g., DANE, pinning, &etc.--because that addresses both cases and provides information a client can intelligently act upon.

Actually, the use case I most often encounter is the one where "a
priori" knowledge exists, and we don't really need to turn to DANE,
TOFU pinsets and the like. However, we have to re-use existing
infrastructure, like a TLS channel and web services.

But sure, I'll take whatever security controls I can get my hands on.
As long as they don't provide overrides so the attacker can control
critical security parameters.