The Design And Implementation Of Intellectual Property Protection Module For Digital TV Set-Top Box

In recent years, with continuous occurrences of pirated software, people have had regard for software protection more and more. To protect software's intellectual property, software encryption techniques has become to an ology. It consists of secret key encryption, preventive-trace technique and code-inserted technique, such as password encryption, disk encryption, extended-card encryption, soft dog and so on. Synthetically analyzing the technique criterion, for instance, reliability write/read speed, convenience, difficulty to decrypt, occupancy of machine resource etc., and soft dog is a good idea for embedded applications. Nowadays, in embedded systems, they add the module composed with a specialized chip protecting from tortious behavior. These chips are mostly soft dog product with E~2PROM at its third generation. They might be attacked and cracked easily by logic analysis at data interface. The fourth generation's soft dog joins a micro-controller as PIC12F6XX comparing to the third one, which load a specific encrypted algorithm in ROM in order to encrypt data between host and slave, to against logic analyzers.This dissertation gives the scheme of the module applicable to STB system, which provides software intellectual property protection. And it is based on microcontrollers of PIC series with authorization and password access E~2PROM, whose data link interface, complied with the I~2C-bus specification by constructing a state machine. The scheme even applies a specific encrypted algorithm to process encrypted transform between host and slave, which can encrypt the data, interfere with the code, and change secret keys at intervals, to against software tracker.At first the essay introduces the software and hardware system of STB, which provides research context for the system design latter. Then we discourse the notion and concept of cryptology, and expound two classical cryptographic algorithms: Stream cipher and DES. By analyzing these cryptographic algorithms, it provides the theoretical guarantee for the secure transmission of soft dog's data. After that is the design and implements of the module for intellectual property protection. We providethe overall design and design the hardware connection of system. Then we design the software, and the emphasis is on the design and debugging. Finally, we give the summary, and think more deeply for the safeness of this system.