Re: [TLS] Short Ephermal Diffie-Hellman keys

[Mike <mike-list at pobox.com>]

> I have recently started to see an increasing number of reports about 
> SSL/TLS servers using short Ephermal Diffie-Hellman keys, in some cases 
> very short ones.
>
> The short DHE keys I have seen have usually been 512 bits, but I have 
> seen servers sending keys as short as 256 bits.

This is probably the result of an administrator not wanting to wait
the extra 30 seconds to generate a strong key.  If the server is
set up to generate a key on startup, it may not start listening for
connections until it has completed the task.

I recall (hopefully correctly) that a 1536 bit D-H key provides the
equivalent of about 90-120 bits of security.  I would guess that a
512-bit or 256-bit key is down in the EXPORT category of security.
This is a terrible trend.

Mike

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