| Summary: | 碩士 === 國立交通大學 === 資訊工程學系 === 86 === A Pay-TV system is a commercial TV system, which charges its
subscribers for receiving the TV programs. The purpose of
channel protection is to insure that only the authorized
subscribers, who have paid the fee, can watch the TV programs,
while an unauthorized viewer can see nothing intelligible. In
many real systems, TV programs are scrambled before
broadcasting, and only the authorized subscribers will get the
keys to descramble the original TV programs correctly. For
higher security consideration, thekeys should be updated
constantly. It is a very inefficient way to send the updated
keys to each subscriber respectively. In this thesis, we
proposed three key distribution schemes for different situations
in order to efficiently and securely distribute the keys to the
authorized subscribers. In these schemes, only one or two
messages are transmitted for updating the keys, and only simple
computation functions, i.e. the symmetric key encryption/
decryption function, the one-way function and the XOR function,
are adopted for implementation in the smart card-based systems.
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