Other Directory Sites: SeekWonder | Directory Owners Forum
The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:20:10 ADT
Ben Laurie (ben@algroup.co.uk)
Tue, 07 Jul 1998 16:03:30 +0100
Perry E. Metzger wrote:
>
> Ben Laurie writes:
> > > People really have to get it through their heads that this is one
> > > field where, when you don't know an answer, you *have* to behave as
> > > though the worst is true, not the best.
> >
> > That is not a helpful argument. I agree you have to assume the worst,
> > but you are suggesting that no matter what I assume it isn't bad enough
> > (because, allegedly, "I haven't got it through my head that this is one
> > field where, when you don't know an answer, you *have* to behave as
> > though the worst is true"). Just suppose, as a wild fantasy, that I have
> > got that through my head. Now, what is the "worst" in this case? If that
> > can't be answered, then the number of bits of entropy I can get per hit
> > is zero, surely?
>
> "Reasonable" worst in this case is probably about the levels that John
> Walker assumed, though. I admit that we have to be reasonable about
> this. What is "reasonable" is, unfortunately, often a matter of
> judgement. I agree that it isn't good. My point was more that your
> language ("aren't we being overly conservative here") tended in a
> dangerous direction rather than the desire to see if you could safely
> extract more data.
Which is why I went on to discuss how one might begin to think about a
reasonable estimate of the entropy.
The problem I'm having is that, as someone pointed out, there appears to
be essentially as much entropy as you have the timing resolution to
count. This makes me think that there is far more than 1/3 of a bit
available per hit, but what actually limits it are, presumably, things
like the accuracy and vulnerability to outside influence of the timer,
speed of response of the tube, accuracy of circuitry that detects the
hit, and so on (incidentally, as often seems to be the case, perhaps
this circuitry is actually the most vulnerable part of the system - how
much radio energy do I have to point at it to control it?). At this
point it becomes rather difficult to analyse.
Cheers,
Ben.
-- Ben Laurie |Phone: +44 (181) 735 0686| Apache Group member Freelance Consultant |Fax: +44 (181) 735 0689|http://www.apache.org/ and Technical Director|Email: ben@algroup.co.uk | A.L. Digital Ltd, |Apache-SSL author http://www.apache-ssl.org/ London, England. |"Apache: TDG" http://www.ora.com/catalog/apache/WE'RE RECRUITING! http://www.aldigital.co.uk/recruit/
The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:20:10 ADT