Fedora/Redhat and perfect forward secrecy

Reindl Harald h.reindl at thelounge.net
Mon Sep 9 16:34:48 UTC 2013

Am 09.09.2013 18:12, schrieb Paul Wouters:
> On Mon, 9 Sep 2013, Reindl Harald wrote:
>>> I don't get it, either
>> google "dhe versus ecdhe performance"
>> http://vincent.bernat.im/en/blog/2011-ssl-perfect-forward-secrecy.html
>>>> Let’s focus on the server part. Enabling DHE-RSA-AES128-SHA cipher suite
>>>> hinders the performance of TLS handshakes by a factor of 3. Using
>>>> ECDHE-RSA-AES128-SHA instead only adds an overhead of 27%. However, if we
>>>> use the 64bit optimized version, the cost is only 15%
>> is that enough to understand why nobody on this world is using DHE and so your
>> "Current Fedora supports perfect forward secrecy just fine" is *far* away
>> from the reality?
> Not for me. I thought TLS was latency bound. The above "factor 3" does
> not state whether TLS client/server were in the same LAN (or even VMs on
> the same host).

it does not matter, the world measures CPU load here

> For the client, clearly CPU is not the limiting factor

if you stay on topic you realize that this does not matter
you can't do PFS to *any* major website these days

> For regular TLS servers, this should also not matter. For fully loaded TLS 
> servers or TLS accelerators, the factor 3 on the CPU load will matter, but 
> we're talking clusters of machines here. Dropping in a few extra machines
> shouldn't be that hard to give your patent-encumbered endusers PFS.

*you* are talking clusters here

>> it does not help much support forward secrecy in a way *nobody* else on this
>> planet is supporting it and so you repsonse below is uneducated - period
> Ignoring the obvious legal (and now potential backdoor) problems with
> ECC is also not very educated

we are speaking about the real world, not about therory

*you can't* do PFS to *any* relevant target because nobody
offers negotiation with DHE - so stay on topic and as long
nothing is *proven* ignore it while it *is* proven that
PFS  doe snot work with Redhat/Fedora systems to the rest
of the world

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