The Design And Study Of PVR Set-Top Box Based On AES Algorithm

Nowadays, the personal video recorder (PVR) function add in the set-top box is more and more important in our life. The PVR users spread the programs illegally, even made this a new trand. The article make a design of PVR set-top box, and the design use AES algorithm in the set-top box, in order to protecte the right of company effectively.The aritcal introduces the study of PVR and AES improvement between domestic and overseas, then point out that high real-time, high safety, low complexity are the goles of video encryption. AES has much advantage on these points. The design use EMMA3SL chip scheme, add the AES before PES analysis in the hardware signal processing. This method can cut down datas which to be encrypted, enhance CPU efficiency, combine the AES algorithm and PVR set-top box perfectlly. In the processing of video and audio encryption, the design made the datas 128 bit each group, do 10 times operation include SubBytes, ShiftRows, MixColumns, AddRoundkey and GetNewEncrypt, use C language to complete AES encryption. Based on this, the article gives the fast encryption scheme, make Mixcolumns process to Shift, Lookup tables, and exclusive-or, it increases the speed of encryption. Last, design the PVR record and play function, choose PIO mode to realize high speed transfer of the hard disc. In the file system, the article chooses FAT32 file system. Through distribute the block dynamicly to realize PVR elementary function, use a method of laying datas in the sectors orderly, and receive better effect.Experiment proved, take hard disc off and connect to another computer, the encryption program can't be played, this means the scheme is feasibility. The effect of the time shift function is fluency. The design make PVR an improvement on encryption and disc's read or write speed.