Subject: [Capwap] lwapp-dtls edits

From: "Scott G. Kelly" <[email-masked]>
Date: Fri, 27 Jan 2006 08:42:48 -0800 (GMT-08:00)

I've noticed some things in the 01 draft that need fixing, and I intend to try to roll those edits in and submit a rev'd draft over the weekend. In particular, there are some adjustments to the state machine diagram, and the PSK algorithm idenitifiers are not consistent with the text (missing DHE and RSA variants, and including plain PSK algorithms even though the text says those must not be supported).

As for the PSK algorithms, the text currently says plain psk's must not be used due to their vulnerability to dictionary attacks.. Some have suggested this is too restrictive, and after thinking it over, I think I agree. It seems like allowing plain psk's but adding the standard admonishments regarding weak passphrases and dictionary attacks might make sense.

So, two questions: first, does anyone have any opinions on the above? Second, does anyone have any other issues that should be considered prior to rev'ing the draft?

Thanks,

Scott

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From: "Nelson, David" <[email-masked]>
Date: Fri, 27 Jan 2006 13:08:35 -0500

Scott G. Kelly writes... [mailto:[email-masked]]

> As for the PSK algorithms, the text currently says plain psk's must
not be
> used due to their vulnerability to dictionary attacks.. Some have
> suggested this is too restrictive, and after thinking it over, I think
I
> agree. It seems like allowing plain psk's but adding the standard
> admonishments regarding weak passphrases and dictionary attacks might
make
> sense.

I don't have any problem with PSK methods, using suitable crypto-suites,
key lengths, and key entropy.  I would recommend including one of there.
As you say, the risk is in generating keys from pass-phrases that have
low entropy and are subject to dictionary attack.