Re: Good enough for crypto?

From: Scott Wilber (swilber_at_comscire.com)
Date: 11/25/03 

Date: 25 Nov 2003 09:12:39 -0800

Mok-Kong Shen <mok-kong.shen@t-online.de> wrote in message news:<3FC305D0.C767B4FD@t-online.de>...
> Scott Wilber wrote:
> >
> > Mok-Kong Shen <mok-kong.shen@t-online.de> wrote:
>
> > > >
> > > > Mok-Kong Shen <mok-kong.shen@t-online.de> wrote:
>
> > > > > Scott Wilber wrote:
> > > > > >
> [snip]
> > > > > > Since we have published a methematical basis for determining the
> > > > > > estimated entropy, .........
> > > > >
> > > > > Very dumb question: What would your entropy estimator
> > > > > deliver, if it is fed with bit sequences from some math
> > > > > constants, e.g. Pi? Thanks.
> > > >
> > > > Your comment is a non sequitur. The referenced entropy estimator is a
> > > > mathematical model of a specific physical configuration. It has
> > > > nothing to do with digits of Pi or any other number. We are not all
> > > > that naive, but thanks anyway for your small addition of entropy.
> > >
> > > The point is: If it is given a bit sequence (of 'unknown'
> > > source), could it always function as expected. If not,
> > > it may have a problem. One seldom knows 'how' a bit
> > > sequence used by the opponent is really generated, right?
> >
> > I suggest you go to the webpage
> > http://www.comscire.com/Products/PCQNG20/ and check out what you are
> > making your comments about. It is not about "giving it a bit
> > sequence." We know exactly how the sequence is being generated since
> > we are generating it. This IS the point.
> >
> > It is not about the philosophical (and sometimes practical) question
> > whether an already-generated sequence has any entropy, real or
> > otherwise. The question is, 'What is the per-bit entropy of a
> > sequence being generated by a particular physical source?'.
>
> I think that my question is also practical: Could a
> (rigorous) 'blackbox' entropy estimator exist in
> reality, i.e. without employing any information of the
> generation process of the bits? An estimator that needs
> 'additional' informations than the bits themselves
> (namely about how the bits are generated etc.) isn't a
> 'genuine' estimator in my view. (In the 'extreme' case
> that additional information supplied could even be of
> the form 'the entropy IS ...', isn't it?)
>
> M. K. Shen

See my response to "Bob" for your answer.

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