In order to be acceptable to authors, publishers, and booksellers, ebooks must have copyright protection that equals or exceeds that possessed by paper books. For traditional books, this means laws to prevent "piracy"--the printing and distribution of books by someone other than their copyright holder--and practical and/or technological barriers to reproduction on the part of consumers. The latter, in the case of paper books, is adequate: photocopying and binding a book is generally more trouble and often more expensive than purchasing another copy, and always less satisfactory.

Ebooks present a particular challenge in this regard because digital data lends itself so well to (unauthorized) copying. As software and music publishing firms know so well, the only solution to this problem is technological: the data, once purchased, must simply be impossible to copy in a useable format.

There is presently no standard means of protecting copyright for ebooks. Each manufacturer of ebook readers (e.g., NuvoMedia and SoftBook) and each electronic publisher (e.g., Fatbrain's Ematter) has come up with its own method of secure distribution and prevention of unauthorized copying.

There is, however, a serious attempt at an open standard in the works. EBX, or Electronic Book eXchange, is a system for applications and devices that uses public-key cryptography for copyright protection and distribution of ebooks. The EBX Working Group is spearheaded by a company called Glassbook; its members include individuals from Adobe Systems, Book Industry Study Group, Coalition for Networked Information, Compaq, HarperCollins, Houghton Mifflin Company, Hewlett Packard, Hitachi, Ingram Lightning Print, J-Stream, Microsoft, RSA Labs, SoftBook Press, Philips Electronics, and Xerox.

The latest draft of the specifications, which has a lucid and useful overview, is available here. For our purposes, the mention of a few features will suffice:

• EBX system does not define a specific "content" file format-- it will work with a variety of formats, including OEB and PDF.
• The system will allow for the lending, giving away, and (authorized) reselling of ebooks. This is valuable for libraries, as well as readers, who are long accustomed to these freedoms.
• The public/private key encryption on which EBX is based is a tested and trusted technology.