[slightly OT] File protection from copying

[Lev Abramov]

Hi All

A friend has just completed writing a book which he wants to market online
as an e-book. He's looking for a file format which would ensure that the
e-book can only be used on one computer and not be circulated freely in
violation of copyright.

MP3 files downloaded to an iPod cannot be transferred to another iPod.

Is there any tool that would protect a text-based document in a similar
manner?

Am I being naive?

TIA -

Lev