Subject: [TLS] Last Call: 'Pre-Shared Key Ciphersuites for Transport Layer Security (TLS)' to Proposed Standard

From: The IESG <[email-masked]>
Date: Fri, 18 Mar 2005 11:05:21 -0500

The IESG has received a request from the Transport Layer Security WG to 
consider the following document:

- 'Pre-Shared Key Ciphersuites for Transport Layer Security (TLS) '
   <draft-ietf-tls-psk-07.txt> as a Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action.  Please send any comments to the
[email-masked] or [email-masked] mailing lists by 2005-04-01.

The file can be obtained via
http://www.ietf.org/internet-drafts/draft-ietf-tls-psk-07.txt

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From: DANIELLLANO <[email-masked]>
Date: Sun, 27 Mar 2005 20:23:39 GMT

>  o  First, TLS may be used in performance-constrained environments
>     where the CPU power needed for public key operations is not
>     available.

Could you give some example of performance-constrained environment?
All the new cell phones from Nokia and Siemens have a full TLS stack,
so you are not talking about using this in cell phones for sure.

>  o  Second, pre-shared keys may be more convenient from a key
>     management point of view.  For instance, in closed environments
>     where the connections are mostly configured manually in advance,
>     it may be easier to configure a PSK than to use certificates.
>     Another case is when the parties already have a mechanism for
>     setting up a shared secret key, and that mechanism could be used
>     to "bootstrap" a key for authenticating a TLS connection.

Why instead of using certificates you just put the public keys of the
peers and trust them?
If you start using a shared symmetric key for lots of peers you always
risk that if one attacker gets the key everything is lost, but if you use
a PKI you don't have this problem as the attacker would have to get the
private keys of all the peers.

I'm totally opposed to this becoming a standard.
It just calls for problems.

Please, don't take steps back. It was hard to get here.