A copyright protection method for digital media is disclosed. The present invention
is designed to solve the problems of the existing media protection systems and
to satisfy all of media owners, distributors, and consumers. The copyright protection
method according to the present invention can be applied to any type of digital
media and makes no assumptions on any particular media properties. The method employs
symmetric and asymmetric cryptographic protection techniques as well as a digital
watermarking method. Cryptography is used to provide the security of the copyright
information access for media managers. Digital watermarking is used to modify the
played or recorded media signals to keep track a list of involved playing devices
in order to detect any illegal copy maker and to identify any legal copy from illegal copies.