using "reserved" IPv6 space

Thu Jul 19 04:40:30 UTC 2012

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.

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.

--
-JH