Re: [TLS] New Version Notification for draft-putman-tls-preshared-ecdh-00.txt

If you add the fourth (static-static) DH, you should be protected
against poor generation of ephemeral keys.

(For example, IoT devices might have a long-term DH key provisioned in
the factory, but broken RNGs. If two of them talk to each other using
triple DH no security is achieved, but if the static-static is included
then the connection will still be secure)

Katriel

On Thu, 30 Nov 2017, at 05:43 PM, Tony Putman wrote:
> Hi,
> 
> I've fleshed out my ideas on the use of triple-ECDH authentication for
> TLS 1.2 into the I-D referenced below. While working on this I came to
> some new conclusions: 
>  - PFS may not be important for IoT, so I included cipher suites using
>  Double-ECDH as well
>  - Protecting the PSK Identity is really easy, so I added that as well
>  - I added the static public keys into the premaster calculation to match
>  the security proof; I don't know if this is necessary
> 
> I suppose that the next step is to find out if anyone else is interested
> in this approach. I'd appreciate it if people could suggest other mailing
> lists who might show an interest (ACE?). Other questions and suggestions
> are welcome. 
> -- 
> Tony
> 
> -----Original Message-----
> From: internet-drafts@ietf.org [mailto:internet-drafts@ietf.org] 
> Sent: 30 November 2017 17:01
> To: Tony Putman
> Subject: New Version Notification for
> draft-putman-tls-preshared-ecdh-00.txt
> 
> 
> A new version of I-D, draft-putman-tls-preshared-ecdh-00.txt
> has been successfully submitted by Tony Putman and posted to the
> IETF repository.
> 
> Name:           draft-putman-tls-preshared-ecdh
> Revision:       00
> Title:          ECDH-based Authentication using Pre-Shared Asymmetric
> Keypairs for (Datagram) Transport Layer Security ((D)TLS) Protocol
> version 1.2
> Document date:  2017-11-30
> Group:          Individual Submission
> Pages:          17
> URL:           
> https://www.ietf.org/internet-drafts/draft-putman-tls-preshared-ecdh-00.txt
> Status:        
> https://datatracker.ietf.org/doc/draft-putman-tls-preshared-ecdh/
> Htmlized:      
> https://tools.ietf.org/html/draft-putman-tls-preshared-ecdh-00
> Htmlized:      
> https://datatracker.ietf.org/doc/html/draft-putman-tls-preshared-ecdh-00
> 
> 
> Abstract:
>    This document defines a new mutual authentication method for the
>    Transport Layer Security (TLS) protocol version 1.2.  The
>    authentication method requires that the client and server are each
>    pre-provisioned with a unique asymmetric Elliptic Curve Diffie-
>    Hellman (ECDH) keypair and with the public ECDH key of the peer.  The
>    handshake provides ephemeral ECDH keys, and a premaster key is agreed
>    using Double- or Triple-ECDH; confirmation of possession of this key
>    provides mutual authentication.  Multiple new cipher suites which use
>    this authentication method are specified.
> 
>                                                                                   
> 
> 
> Please note that it may take a couple of minutes from the time of
> submission
> until the htmlized version and diff are available at tools.ietf.org.
> 
> The IETF Secretariat
> 
> 
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