Hi,

We seem to be designing this protocol one mail at a time. Could
I ask that we stop doing that and that Karl and whoever else is
minded submit an internet-draft specifying the protocol so that
it can be more easily reviewed.

Thanks,
Stephen.

PS: Karl, if you need help with the mechanics just ask me
offlist.

On 09/12/2013 05:24 PM, Karl Malbrain wrote:
> The assumed attack profile is a MITM insertion into a connection stream 
> between server and client whereby the attacker gains complete unencrypted 
> access to all traffic over the connection, not just meta data.
> 
> TLS already has a built-in concept of "strong authentication" between server 
> and client to defeat this attack.  It requires that the TLS server pre-obtain 
> by some secondary channel the public key of the user.  This proposal 
> eliminates that requirement by making the user's public keys public knowledge.
> 
> Karl
> 
> From: Jon Callas [mailto:[email protected]]
> Sent: Thursday, September 12, 2013 06:21
> To: Karl Malbrain
> Cc: Jon Callas; Phillip Hallam-Baker; Theodore Ts'o; [email protected]
> Subject: Re: [perpass] proposed enhancement to TLS strong authentication 
> protocol
> 
> 
> On Sep 11, 2013, at 11:56 AM, Karl Malbrain 
> <[email protected]<mailto:[email protected]>> wrote:
> 
> 
> The goal of the proposal is to enable the use of strong authentication for 
> all TLS connections over the internet.  The certificates as 
> things-in-themselves don't really matter, they are actually just a vehicle to 
> post the public key of the user/server in a reliable public place.  The 
> security occurs when the challenges to prove private key ownership are 
> cross-issued by each party.  MITM would not have the private keys to answer 
> either challenge.
> 
> Note that this still doesn't solve the problem of MITM obtaining the server's 
> private key.  I'm still working on that one.
> 
> I might be misunderstanding, but it seems to me that your global directory 
> would allow a passive listener to fingerprint the client by sniffing in a 
> variety of places -- near the client, near the server, or near the directory.
> 
> If you assume an attacker interested in collecting metadata about the 
> clients, this would be suboptimal.
> 
> I may be missing something, but this sounds like it is just a global, central 
> certificate authority, albeit one that is not actually issuing the 
> certificates, but still assigning them GUIDs, which are by definition 
> globally unique.
> 
> Am I indeed missing something?
> 
>             Jon
> 
> 
> 
> 
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