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Date:      Sun, 24 Jun 2012 14:26:02 -0400
From:      Robert Simmons <rsimmons0@gmail.com>
To:        freebsd-security@freebsd.org
Subject:   Re: Add rc.conf variables to control host key length
Message-ID:  <CA%2BQLa9BGW6=kpNfLZ%2BhkUiaWEHgcxCaQAG4ceGEtNZtNwsHejw@mail.gmail.com>
In-Reply-To: <20120624181543.GA3652@DataIX.net>
References:  <CA%2BQLa9CX26xEwRsz3g6FvBBbbFE0Gfw%2BUR6_RHYOXgZFcgCw5w@mail.gmail.com> <4828EFCC-E60A-4961-9228-4A1ADAD28F73@lists.zabbadoz.net> <20120624165920.GA85913@DataIX.net> <CA%2BQLa9C04d3fkk6r2apLti4vn%2BJ8_fai--qK2yQobmXD%2BbdTww@mail.gmail.com> <20120624181543.GA3652@DataIX.net>

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On Sun, Jun 24, 2012 at 2:15 PM, J. Hellenthal <jhellenthal@dataix.net> wro=
te:
> On Sun, Jun 24, 2012 at 01:26:21PM -0400, Robert Simmons wrote:
>> On Sun, Jun 24, 2012 at 12:59 PM, J. Hellenthal <jhellenthal@dataix.net>=
 wrote:
>> > These are more then sufficient for any normal ssh use.
>>
>> I'm sorry if I sound rude, but I wanted to have a bit more of a
>> substantive discussion than quoting the man pages. =A0Especially since
>> what you are quoting dates back to a change to
>> src/crypto/openssh/ssh-keygen.1 dated the following:
>> Sun Sep 11 16:50:35 2005 UTC (6 years, 9 months ago) by des
>>
>> Being that the old "considered sufficient" of 1024 was added at the
>> following revision date:
>> Thu Feb 24 14:29:46 2000 UTC (12 years, 4 months ago) by markm
>>
>
> There is nothing stopping you from changing a key after the system has
> booted e.g. by using the rc script itself if you feel it is not
> sufficient.

Almost.  If you use /etc/rc.d/ssh keygen all you will get is the
default sizes again.  If you apply the patches I've suggested earlier,
this can be used to change the keys to your liking.  As I said, my
patches don't change the default, they just add knobs to rc.conf that
allow /etc/rc.d/ssh keygen to work as someone would want it to work if
they want different key sizes.

> Given OpenBSD is usually always on the far safe side of things taking
> the security approach before simplicity I would extremely agree that it
> is more than sufficient.
>
> But then again what is good for the masses it not always good enough for
> the security paranoid and giving credit to such is what keeps everyone
> safe.
>
> ( /usr/local/etc/rc.d/openssh keygen ) # regenerate your keys
>
> Which should generate a new set of keys, keeping you safe for another X
> amount of years.
>
> =A0- or -
>
> ssh-keygen -f rsa -b [NNNN] -f /usr/local/etc/ssh/ssh_host_rsa_key

See above.  I've included patches that simplify this.

> But the intitial key being the default? its sufficient to get you in and
> started on a remote system.
>
>> I would say that we are exactly due for a real discussion as to what
>> should be considered sufficient with regards to modern processors and
>> GPUs.
>
> Unfortunately I see that as a different thread "Hardware potential to
> duplicate existing host keys... RSA DSA ECDSA"

I see it as related directly to why or why not 2048 is sufficient.

Do you have an argument for the 2048 default based on something more
than OpenBSD does it?



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