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\rightline{\sevenrm April 12, 2000}
\smallskip

\centerline{\largerbold Protecting Intellectual Property in the Digital Era}

\bigskip

\noindent {\bf Encryption}

\medskip

We've studied various methods during this semester. In practice,
encryption methods used to protect intellectual property may rely both
on ``software'' or ``hardware''. We've discussed some possible
software methods relying on the difficulty of certain algorithms to be
unravelled without knowledge of their keys. Special purpose hardware
has been designed to forestall copying or access to intellectual
property. This could take the form of special computer chips encased
in decoder boxes or special attachments for computers
(``dongles''). These can be unwieldy and unpopular. Digital property
when converted to plaintext can perhaps just be copied unless
additional intricate arrangements are made. Also, decryption can be
elaborate and take time, and its intricacies can be another level of
complexity subject to malfunction during delivery of the
property. Additionally, of course, encryption schemes can be
broken. The most notorious recent case is the cracking of the DVD
protection scheme.

Here's a paragraph from an official Memorandum of the U.S.~District
Court published in January 2000 (source: a web page at {\tt
www.eff.org}):

\smallskip

{\qqq

DVDs contain motion pictures in digital form, which presents
an enhanced risk of unauthorized reproduction and distribution because
digital copies made from DVDs do not degrade from generation to
generation. Concerned about this risk, motion picture companies,
including plaintiffs, insisted upon the development of an access
control and copy prevention system to inhibit the unauthorized
reproduction and distribution of motion pictures before they released
films in the DVD format. The means now in use, Content Scramble System
or CSS, is an encryption-based security and authentication system that
requires the use of appropriately configured hardware such as a DVD
player or a computer DVD drive to decrypt, unscramble and play back,
but not copy, motion pictures on DVDs. CSS has been licensed to
hundreds of DVD player manufacturers and DVD content distributors in
the United States and around the world.

}

\smallskip

\noindent The licensees are required to keep the algorithms and keys
secret, and to install tamper-proof hardware in each player which
would contain the keys needed to read those DVD's legal for the
player's area in the world. The DVD organization divided the world
into several distinct areas: discs and players could each work only in
designated areas.

CSS turns out to be a rather simple encryption scheme relying on 40
bit keys (not adequate by current encryption standards). The system
was reverse engineered: that is, observation of the inputs and outputs
of the system were used to figure out how the system worked. Also, one
of the manufacturers mistakenly allowed some of the keys to be
seen. Even extremely secure cryptosystems may be vulnerable when users
make mistakes.

The following quotes are taken from pages on {\tt
http://www.wired.com}. The first is from, of course, a representative
of those wishing to protect their intellectual property. The second
is from the ``crackers''.

\smallskip


{\qqq        

``The circulation through the Internet of the illegal and
inappropriate software is against the stream of copyright
protection. Toshiba, which has led the establishment of the DVD format
and is the chair-company of the DVD Forum, feels it is a great pity,''
wrote Masaki Mikura, manager of the strategic partnership and
licensing division at Toshiba Ltd.

\sk

Johansen and his partners were able to guess more than 170 working
keys by trial and error before finally just giving up to go do
something else. ``I wonder how much they paid for someone to actually
develop that weak algorithm,'' said Johansen. ``It's a very weak
encryption algorithm.''

} 

\smallskip
\rightline{\bf OVER}\vfil\eject
\noindent {\bf Steganography}

\medskip

\noindent From the web page {\tt
http://www.cl.cam.ac.uk/$\tilde{\hphantom{e}}$fapp2/steganography/}:

\smallskip

{\narrower\vx\baselineskip=.7\baselineskip While cryptography is about
protecting the content of messages $\scriptstyle\ldots$ {\vb
steganography} is about concealing their very existence. It comes from
Greek roots and literally means ``covered writing,'' and is usually
interpreted to mean hiding information in other information.

\sk

Until recently, information hiding techniques received very much less
attention from the research community and from industry than
cryptography, but this is changing rapidly $\scriptstyle\ldots$ The
main driving force is concern over protecting copyright; as audio,
video and other works become available in digital form, it may be that
the ease with which perfect copies can be made will lead to
large-scale unauthorized copying which will undermine the music, film,
book and software publishing industries. There has therefore been
significant recent research into ``watermarking'' (hidden copyright
messages) and ``fingerprinting'' (hidden serial numbers or a set of
characteristics that tend to distinguish an object from other similar
objects); the idea is that the latter can be used to detect copyright
violators and the former to prosecute them.

\rightline{\copyright 1997-1999 by Fabien A.~P.~Petitcolas, Computer
Laboratory, University of Cambridge\qquad \ }

}

\smallskip
  
\noindent From the webpage 
{\tt http://members.tripod.com/steganography/stego.html}:

\smallskip
{\narrower\vx\baselineskip=.7\baselineskip

\noindent {\vb What is Steganography?}
\sk

In an ideal world we would all be able to openly send encrypted mail
or files to each other with no fear of reprisals. However there are
often cases when this is not possible, either because you are working
for a company that does not allow encrypted email or perhaps the local
government does not approve of encrypted communication (a reality in
some parts of the world). This is where steganography can come into
play.

\sk

Steganography simply takes one piece of information and hides it
within another. Computer files (images, sounds recordings, even disks)
contain unused or insignificant areas of data. Steganography takes
advantage of these areas, replacing them with information (encrypted
mail, for instance). The files can then be sent or transported without
anyone knowing what really lies inside of them. An image of the space
shuttle landing might contain a private letter to a friend. A
recording of a short sentence might contain your company's plans for a
secret new product. Steganography can also be used to place a hidden
``trademark'' in images, music, and software, a technique referred to
as watermarking.

\rightline{\copyright 1997, 1998 Eric Milbrandt\qquad \ }
}

\smallskip

\noindent Steganography is not a commonly used word, but steganography
is more commonly applied than is realized. These paragraphs are from a
message on the cypherpunks mailing list:

\smallskip

{\qqq \sk

$\scriptstyle\ldots$ when the potential for counterfeiting of valuable
documents on color copiers/xerographic printers became apparent in
Japan (where such machines first appeared) manufacturers were
concerned about negative governmental reaction to such technology.  In
an effort to stave off legislative efforts to restrict such devices,
various ID systems began being implemented at that point.  At one
stage for at least one U.S.  manufacturer, this was as crude as a
serial number etched on the underside of the imaging area glass!

\sk

Modern systems, which are now reportedly implemented universally, use
much more sophisticated methods, encoding the ID effectively as
{\eighttt "}noise{\eighttt "} repeatedly throughout the image, making
it impossible to circumvent the system through copying or printing
over a small portion of the image area, or by cutting off portions of
printed documents. $\scriptstyle\ldots$

\sk

To read these IDs, the document in question is scanned and the
{\eighttt "}noise{\eighttt "} decoded via a secret and proprietary
algorithm.  In the case of Xerox-manufactured equipment, only Xerox
has the means to do this, and they require a court order to do so
(except for some specific government agencies, for whom they no longer
require court authorizations).  I'm told that the number of requests
Xerox receives for this service is on the order of a couple a week
from within the U.S.

\sk

In the copier case, that ID technology being used for color copies
*could* be adapted to black and white copies and prints as well.  The
addition of cheap GPS [global positioning systems: my note] units to
copiers could provide not only valid date/time stamps, but also the
physical *locations* of the units, all of which could be invisibly
encoded within the printed images.

\sk

Pressures to extend the surveillance of commercial copyright
enforcement take such concepts out of the realm of science-fiction,
and into the range of actual future possibilities.

}
\vfil\eject


There are lots of bits in most digital property whose alteration would
hardly be noticed by a human observer. Huge music files have lots of
room: the ear can hardly hear that well. And pictures $\ldots$ so much
can be hidden in even the simplest pictures.

\bigskip
\noindent {\bf A problem in steganography} 
\medskip

Describe carefully at least 3 ways to hide 20 bits in the picture
below, without harming its artistic {\sl integrity or
quality}\footnote*{\sevenrm Assuming there is any.}. 20 bits is enough
to encode more than a million distinct numbers since $2^{20}$ is
1,048,576.

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