Re: [TLS] TLS Proxy Server Extension
David McGrew <mcgrew@cisco.com> Tue, 02 August 2011 00:14 UTC
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From: David McGrew <mcgrew@cisco.com>
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Date: Mon, 01 Aug 2011 17:13:14 -0700
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Cc: pgladstone@cisco.com, tls@ietf.org
Subject: Re: [TLS] TLS Proxy Server Extension
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On Aug 1, 2011, at 1:38 PM, Martin Rex wrote: > David McGrew wrote: >> >> Martin Rex wrote: >>> >>> You're trying to give the proxy the authority to impersonate >>> _every_ server. >> >> On the contrary, the goal here is to not have the proxy impersonate >> any other device, at least not impersonate in the cryptographic >> sense. > > Exactly in that sense. You do not have the slightest proof that > the server, which your proxy impersonates, is actually involved. > The proxy could be making up the entire conversation and the > client will not be able to tell the difference. > > >> >> I think the right theoretical approach to analyzing this sort of >> protocol would be to start with a formal model of TLS as a two-party >> authentication protocol, and extend it to accomodate a three-party >> system with the appropriate role definitions. > > Been there, done that, and really disliked it: > http://tools.ietf.org/html/draft-housley-evidence-extns-01 > > >> >>>> >>>> It would make crypto validation considerably harder if not >>>> impossible. >>> >>> Nope. That is orthogonal. >> >> On the above three points: allowing a proxy to coordinate betwen two >> TLS sessions allows one to preserve most of the TLS protocol and >> implementation. > > You mean by having the entire TLS security architecture walk the > plank, > you could get away with fairly minor code changes? > > >> >> It seems like a major difference that we have is that you expect a >> "read only" solution to be viable, while I don't. A read-only >> decryption proxy would be considerably easier to implement correctly. >> However, I have zero confidence that a read-only decryption proxy >> would not evolve into a read/write proxy, which would introduce very >> significant security problems. > > Such an evolution would have the prerequisite of a client cooperating. > > And your solution to not have pretty TLS loose virginity at some point > in the future, is to rape her right away, i.e. start with an > almighty TLS proxy? > > > -Martin Those are colorful metaphors. I assume that if you are willing to deploy such rhetorical excess, you do not actually understand what is being proposed. David
- [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension Yngve N. Pettersen
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension Yoav Nir
- Re: [TLS] TLS Proxy Server Extension Yoav Nir
- Re: [TLS] TLS Proxy Server Extension Adam Langley
- Re: [TLS] TLS Proxy Server Extension Yoav Nir
- Re: [TLS] TLS Proxy Server Extension Adam Langley
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension Matt McCutchen
- [TLS] Certificate pins vs. MITM proxies Matt McCutchen
- Re: [TLS] TLS Proxy Server Extension Martin Rex
- Re: [TLS] TLS Proxy Server Extension Matt McCutchen
- Re: [TLS] TLS Proxy Server Extension Matt McCutchen
- Re: [TLS] TLS Proxy Server Extension Martin Rex
- Re: [TLS] TLS Proxy Server Extension Marsh Ray
- Re: [TLS] TLS Proxy Server Extension Yoav Nir
- Re: [TLS] TLS Proxy Server Extension Marsh Ray
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension Martin Rex
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension Martin Rex
- Re: [TLS] TLS Proxy Server Extension Martin Rex
- Re: [TLS] TLS Proxy Server Extension Marsh Ray
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension Marsh Ray
- Re: [TLS] TLS Proxy Server Extension Yoav Nir
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension Yoav Nir
- Re: [TLS] TLS Proxy Server Extension Marsh Ray
- Re: [TLS] TLS Proxy Server Extension Martin Rex
- Re: [TLS] TLS Proxy Server Extension Martin Rex
- Re: [TLS] TLS Proxy Server Extension Martin Rex
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension Martin Rex
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension Yoav Nir
- Re: [TLS] TLS Proxy Server Extension Anders Rundgren
- Re: [TLS] TLS Proxy Server Extension Yoav Nir
- Re: [TLS] TLS Proxy Server Extension Ken Peirce
- Re: [TLS] TLS Proxy Server Extension Peter Gutmann
- Re: [TLS] TLS Proxy Server Extension Matt McCutchen
- Re: [TLS] TLS Proxy Server Extension Martin Rex
- Re: [TLS] TLS Proxy Server Extension Joshua Davies
- Re: [TLS] TLS Proxy Server Extension Yoav Nir
- Re: [TLS] TLS Proxy Server Extension Ken Peirce
- Re: [TLS] TLS Proxy Server Extension Philip Gladstone
- Re: [TLS] TLS Proxy Server Extension Kemp, David P.
- Re: [TLS] TLS Proxy Server Extension David McGrew
- Re: [TLS] TLS Proxy Server Extension Ralph Holz