Re: [TLS] draft-sheffer-tls-bcp: DH recommendations

Michael Ströder <> Wed, 18 September 2013 18:46 UTC

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Subject: Re: [TLS] draft-sheffer-tls-bcp: DH recommendations
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Yaron Sheffer wrote:
> please see my mail message that started this thread, way back on Sunday :-)

Reading this posting your main objections against MODP DH are interop issues
of today's implementation. Right? This leads me to a more general question...

First, I really appreciate that you write down this BCP document.
But I wonder what the exact scope should be.

In the abstract you say "existing standards and implementations", I guess to
exclude approaches yet to be defined in a new standard. Agreed.
But does that also exclude pushing implementors to slightly improve their
software? The "deployers rather than for implementers" in the introduction
sounds like it.

If that's the scope you're stuck into recommending the least common
denominator of today's implementations and implementors can take your RFC as
excuse to stop improving their implementations.
Also you're in the trap of choosing "widely-used" implementations for your
"Implementation Status" section which is always questionable depending on
personal deployments, especially since the main focus now seems to be web
servers and browsers.

Frankly I have no idea how to get out of this though.

Ciao, Michael.

> On 09/18/2013 05:21 PM, Michael Ströder wrote:
>> On Wed, 18 Sep 2013 13:07:58 +0300 Yaron Sheffer <> wrote
>>> There are multiple issues
>>> with MODP DH in TLS (performance is just one of them).
>> Could you please elaborate on this.
>> Ciao, Michael.