[hashcash] Re: stamp creation std. deviation
- From: Justin <justin-hashcash@xxxxxxxx>
- To: hashcash@xxxxxxxxxxxxx
- Date: Fri, 13 Aug 2004 15:25:23 +0000
On 2004-08-13T09:07:44-0400, Adam Back wrote:
> Yes. It's just the 21st bit of a 20 bit stamp with type B would
> _have_ to be 1 whereas now (type A) it can be either 0 or 1.
Yes, but I think you miss my meaning.
The new scheme (B) is indistinguishable computationally (or wrt entropy
or probability distributions) from a 21-bit stamp.
You don't gain any advantage. You could specify any pattern you wanted
for collisions. For a 20-bit stamp, some could be:
01010101010101010101
10101010101010101010
00000000000000000000 (current)
00010000000100000001
What you propose is
000000000000000000001, which is a 21 bit pattern, therefore it is the
equivalent of a 21-bit stamp under the current validation scheme.
> On Fri, Aug 13, 2004 at 12:46:47PM +0000, Justin wrote:
> > On 2004-08-13T05:47:07-0400, Adam Back wrote:
> > > A. (as in v1) value = claimed_bits if claimed_bits <= measured_bits
> > >
> > > B. or value = claimed bits if claimed_bits == measured_bits
> > >
> > > What happens to the std. deviation -- is it better with type B or type
> > > A?
> >
> > A mandatory 20-bit stamp is no different than a 21-bit stamp under the
> > current scheme, right? The 21st bit just has to be 1 instead of 0.
>
--
"When in our age we hear these words: It will be judged by the result--then we
know at once with whom we have the honor of speaking. Those who talk this way
are a numerous type whom I shall designate under the common name of assistant
professors." -- Kierkegaard, Fear and Trembling (Wong tr.), III, 112
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