Download What can digital watermarking share with cryptography and coding

What can digital watermarking share with cryptography and coding theory?
Roberto Caldelli, Università di Firenze
The advent of the Internet has allowed the development of new services for the users based
on the distribution of multimedia data: the industry is investing to deliver audio, image and
video data in electronic form to customers,
and broadcast televisions, major corporations
and photo archives are converting their contents from analogue to digital form. Initially
the problems of bandwidth have strongly restricted the spreading of true multimedia services, so that only audio data and still images
have been highly distributed. Recently, the improvements of transmission technology have allowed to overcome the bottleneck represented
by the limited bandwidth, so that nowadays it is
easier to transmit also video data over the Internet, where the users will be soon able to enjoy
services like video-on-demand and interactive
television.
Nevertheless a new problem is raising: the
protection of the Intellectual Property Rights
(IPR) of multimedia data distributed in an opennetworked environment. As a matter of fact, the
future development of networked multimedia
services is conditioned by the achievement of
efficient methods to protect data owners against
non-authorised copying and redistribution of
the material put on the network, to grant that
the IPR are well respected and the assets properly managed.
Copyright protection of multimedia data has
been initially accomplished by means of cryptography algorithms to provide control over data
access and to make data unreadable to nonauthorised users. However, encryption systems
do not completely solve the problem, because
once encryption is removed there is no more
control on the dissemination of data; a possible
solution envisages the use of digital watermarking of multimedia works to allow their distribution to be tracked. In this way the number of
permitted copies is not limited, but the possibility to control the path the original work has been
disseminated through really exists.
A digital watermark is a signal permanently
embedded into digital data that can be detected
or extracted later by means of computing operations to make an assertion about the data. The
watermark is hidden into the host data in such a
way that it is inseparable from the data and can
resist to many operations not degrading the host
document. By means of watermarking the work
is still accessible, but permanently marked.
A wide variety of watermarking schemes has
been introduced addressing many different application scenarios: copyright protection, data
authentication, ownership identification etc. A
great deal of research has been devoted to the
study of different means of labelling data and to
the development of robust watermarking techniques, i.e. techniques capable of hiding the watermark in such a way that it can not be destroyed by intentional or unintentional attacks.
Many interesting approaches have been proposed and important steps have been done toward the solution of these important problems.
In this talk, after a general overview on digital
watermarking, some main aspects that directly
link digital watermarking to cryptography and
coding theory will be addressed; in particular it
will be highlighted which are the theoretical issues, taken from cryptography and coding, and
adopted within watermarking technologies.
Industrial Days
Giornate di Matematica per l’Industria
Milan, 1 December 2003