In the traditional, manual working environment, information (in the form of texts, numbers,
etc.) and medium (such as paper) were closely intertwined. Long experiences in their usage and
the application of anti-counterfeit technology have made traditional forms of information very
difficult to alter. Similarly, it was also difficult to send bogus information by an impersonator.
Even those who succeeded in doing so usually were discovered very easily. In today's world of
information and technology, the Internet is rapidly changing many ways people do things.
Similarly, it has also introduced many management problems. For man and information to
interact, there is a need to establish a reliable information system workingenvironment in whichwe grasp, distribute, store and manage information. Such an environment must be able to provideample protection against tampering, stealing, delaying, transmission by fictitious parties, denial of having faxed a document, illegal intrusion and the like. Only so can we build a strong foundation for an information society.