With the increase of commercial multimedia applications using digital video, the security of video data becomes more and more important. Although several techniques have been proposed in order to protect these video data, they provide limited security or introduce significant overhead. This paper proposes a video security scheme for MPEG video compression standard, which includes two methods: DCEA (DC Coefficient Encryption Algorithm) and "Event Shuffle." DCEA is aim to encrypt group of codewords of DC coefficients. The feature of this method is the usage of data permutation to scatter the ciphertexts of additional codes in DC codewords. These additional codes are encrypted by block cipher previously. With the combination of these algorithms, the method provides enough security for important DC component of MPEG video data. "Event Shuffle" is aim to encrypt the AC coefficients. The prominent feature of this method is a shuffling of AC events generated after DCT transformation and quantization stages. Experimental results show that these methods introduce no bit overhead to MPEG bit stream while achieving low processing overhead to MPEG codec.

Transient numerical analysis of electrical signal injection into the surface CCD is given regarding the potential equilibration method. The analysis is composed of the charging and discharging processes of signal charges, characterized by time intervals TC and TD of the respective input pulses. A concept of setting time TS" explains how the mode of injection converts from the potential equilibration to dynamic injection, and determines a optimum TC . A concept of residual effect of excess charges" is discussed in relation to sampling effect. The procedure to determine a optimum TD is also proposed. It is concluded that the optimum TC and TD for completion of linear charge preset are determined by device geometry (that is, electrode lengths of the CCD input gates), while the TC also depends on the bias condition of the input pulses. The above conclusions can be applied to setting input pulses and the structure of CCD inputs designed for analog signal processing.