using "reserved" IPv6 space

Thu Jul 19 12:47:14 UTC 2012

In message <CAAAwwbXh1wS_9aX4FwGrqmSBJmKGJ0nWHRi9EN53HtL36VhSSg at mail.gmail.com>
, Jimmy Hess writes:
> On 7/18/12, Karl Auer <kauer at biplane.com.au> wrote:
> > I don't understand the professed need for provable randomness. Without a
> > number *space* to provide context, randomness is inherently
> > non-provable. The whole point of the randomness of those 40 bits of ULA
> > infix is that any number is as likely as any other number. Someone,
> 
> When numbers are selected by choosing a random value;  certain ratios
> of bits set to "1" are more likely to occur than other ratios of bits
> set to "1".
> 
> A random generator that is operating correctly, is much more likely to
> emit a number with 50% of the bits set to 1,   than it is to emit a
> number with 0% of the bits set to 1, given a sufficient number of
> bits.   If the ratio is inconsistent by a sufficient margin, and your
> sample of the bits is large enough in number,   you can show with high
> confidence that the number is not random;   a  1 in 10 billion chance
> of the number being randomly generated, would be pretty convincing,
> for example.

Actually you can't.

	fdaa:aaaa:aaaa has 20/20 0/1 bits but is entirely non random.
	fdf0:f0f0:f0f0 has 20/20 0/1 bits but is entirely non random.

The ratio of the number of bits doesn't tell you anything about whether
the number was random or not.

> Removing the temptation  by excluding the small number of choices with
> 90%  - 95%  of the bits set to 1  may eliminate future problems caused
> by an early "accident"/"error" in assigning the initial ULA,
> compared to the minor inconvenience of needing to run the ULA
> generator one more time to get an actual usable range.
> 
> > somewhere, is eventually going to get 10:0000:0000, someone else will
> > eventually get 20:0000:0000 and so on. And they are just as likely to
> > get them now as in ten years time.
> 
> That is extremely improbable.
> If you generate a million ULA IDs a day,  every day, it is expected to
> be over 1000 years before you generate one of those two.

	improbable != impossible

> --
> -JH
> 
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org