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Date:      Tue, 18 Jul 2000 08:24:58 +0200
From:      Poul-Henning Kamp <phk@critter.freebsd.dk>
To:        Mark Murray <mark@grondar.za>
Cc:        current@FreeBSD.ORG
Subject:   Re: randomdev entropy gathering is really weak 
Message-ID:  <7217.963901498@critter.freebsd.dk>
In-Reply-To: Your message of "Tue, 18 Jul 2000 08:17:57 %2B0200." <200007180617.IAA03375@grimreaper.grondar.za> 

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In message <200007180617.IAA03375@grimreaper.grondar.za>, Mark Murray writes:
>> People have tried for 30+ years to predict what a quartz xtal
>> will do next.  Nobody expects any chance of success.  Add to this
>> the need to predict the difference between one or more NTP servers
>> and your local qartz xtal and I think we can safely say "impossible".
>
>You can't predict this, but you can _measure_ it with a degree of
>accuracy. The attacker can use this accuracy to reduce the number
>of tries in his attack.

No he cannot.  The NTP poll period is 64 seconds or longer and unless
you have done something special about your hardware, he cannot predict
all bits.


If he could, ntp would have a longer poll period :-)

--
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD coreteam member | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


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