On 23/09/13 09:47, Peter Gutmann wrote:
Patrick Pelletier <c...@funwithsoftware.org> writes:

I'm inclined to agree with you, but you might be interested/horrified in the
"1024 bits is enough for anyone" debate currently unfolding on the TLS list:

That's rather misrepresenting the situation.  It's a debate between two
groups, the security practitioners, "we'd like a PFS solution as soon as we
can, and given currently-deployed infrastructure DH-1024 seems to be the best
bet", and the theoreticians, "only a theoretically perfect solution is
acceptable, even if it takes us forever to get it".

(You can guess from that which side I'm on).

Lessee - a "forward secrecy solution" which either doesn't work now or won't work soon - so that it probably won't protect traffic made now for it's useful lifetime - versus - well, who said anything about theoretically perfect?

To hell with perfect. I won't even use the word when describing forward secrecy (unless it's an OTP).

If you just want a down-and-dirty 2048-bit FS solution which will work today, why not just have the websites sign a new RSA-2048 sub-certificate every day? Or every few hours? And delete the secret key, of course.

Forward secrecy doesn't have to be per-session.

Though frankly, I don't think ubiquitous 1024-bit FS without deployment of some software/RFC/standard is possible, and if so that deployment should also include a 2048-bit solution as well. And maybe 3072-bit and 4096-bit solutions too.

And please please please don't call them all the same thing - because they aren't.

But, the immediate question before the court of TLS now is - "do we recommend a 1024-bit FS solution?"

And I for one cannot say that you should. In fact I would be horrified if you did.

-- Peter Fairbrother
The cryptography mailing list

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