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Re: Think Piece: Key Free Trust in the Semantic Web

From: Aaron Swartz <me@aaronsw.com>
Date: Thu, 04 Apr 2002 21:51:23 -0600
To: "Joseph M. Reagle Jr." <reagle@w3.org>, RDF-Interest <www-rdf-interest@w3.org>
Message-ID: <B8D27B5B.2F98F%me@aaronsw.com>
On 2002-04-04 09:34 PM, "Joseph Reagle" <reagle@w3.org> wrote:

> On Thursday 04 April 2002 20:45, Aaron Swartz wrote:
>> PKI and Web-of-Trust networks are designed to foil Man-In-The-Middle
>> (MITM) attacks, not who's-key-is-this? problems.
> 
> I don't follow. For public keys, they are largely the same problem. My
> scenarios is orientated towards validating a signature on a single
> document. The Man-in-the-Middle scenario is orientated towards the exchange
> of multiple interactive documents. (The person can sit in the middle
> proxying the messages back and forth watching the conversation while
> fooling both sides.) But, they share the same problem of, "This is really
> Andrew's (or Bacon's) key." [a]

MITM can occur in the static document scenario, if you imagine the Man
sitting at your ISP, slyly rewriting all the crypto that comes thru. (I
admit, this is a very paranoid scenario.) The attack here would be to feed
you (seemingly signed) documents that the real person never signed.

 
> The nature of the threat might be different, but the problem is to be sure
> one has the right key.

On the Semantic Web, I'd treat that as a normal trust problem, the same way
I'd want try to make sure that the triple "x y z" was true. How is finding
John's key any different than finding who won some war, or any other
question you might ask the Semantic Web? It's just a set of bits, like any
other.

> [a] http://www.silicon-trust.com/background/sp_pki.htm
> [[
> [...] One problem is that if a
> hacker has knowledge of your private key information, they can intercept a
> message and replace the public key with one of his or her own. This is
> known as a man-in-the-middle attack.

Huh? You can execute a MITM attack without knowing someone's private key --
that's the whole point.

-- 
[ "Aaron Swartz" ; <mailto:me@aaronsw.com> ; <http://www.aaronsw.com/> ]
Received on Thursday, 4 April 2002 22:51:29 GMT

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