semi-public data?? (Re: phone lookups)

[Peter Fairbrother]

Adam Back wrote:

> I think a more pertinent question is:
> 
> - is the information public or not?
> 
> if it's public it's public -- no semi-public, or public but only to
> people who pay 200 pounds, or public to people who show up at an
> office.

There is an unmentioned difference here, brought about partly by the
development of computer search programs, although the distinction existed
before. Information is useless unless it is *looked at.

Anyone can look up someone's number in a telephone directory, from knowing
who that someone is, but it is illegal in the UK to look up the someone from
a number.

In terms of a forward lookup a listing in the phone book is public. In terms
of reverse lookup it isn't public (at least in law and public perception,
although in practice it is).



[I could** devise a cryptographic solution to implement the one-way nature
of the public perception of telephone directory lookups, but unfortunately
at a cost that would be enormous, involving a change to the way the phone
number system works. This won't happen in real life.]



-- Peter Fairbrother


*[OT] trees falling, forests, nobody there, sound, does it exist? It does if
you _might_ look, c/f Elitzur-Vaedman Bomb Testing (!).

**[OT] But there is the question; do one-way functions exist?