Re: [TLS] AD review of draft-ietf-tls-negotiated-ff-dhe-08

[Santiago Zanella <[e-mail]>]

Peter Gutmann <[e-mail]> wrote:
> So... if 8.7% is the most widely-used group (since you qualify the
> 7.8% one with "the most common with a modulus longer than 1024
> bits")

That does not follow from what I said. The 8.7% group is the 4th most
common, the top 3 have also 1024-bit moduli.

> that means the most common group is one that the ff-dhe draft
> doesn't allow you to specify, and the most common group with a
> modulus longer than 1024 bits is... another one that the ff-dhe
> draft doesn't allow you to specify.

Yes, and rightfully so because we want to get rid of 1024-bit groups
and have good reasons not to reuse groups from other protocols. But
note that the draft reserves codepoints for private use that can be
used locally to specify other groups.

The minimum acceptable size was set at 2048 bits was a result of a
straw poll:

 http://www.ietf.org/mail-archive/web/tls/current/msg14438.html

 --Santiago