Selective video encryption of distributed video coded bitstreams and multicast security over wireless networks.

摘要

Here we discuss two security problems, video data encryption and multicast security, in wireless networks.; Selective encryption is a technique that is used to minimize computational complexity or enable system functionality by only encrypting a portion of a compressed bitstream while still achieving reasonable security. For selective encryption to work, we need to rely not only on the beneficial effects of redundancy reduction, but also on the characteristics of the compression algorithm to concentrate important data representing the source in a relatively small fraction of the compressed bitstream. These important elements of the compressed data become candidates for selective encryption. In this thesis, we combine encryption and distributed video source coding to consider the choices of which types of bits are most effective for selective encryption of a video sequence that has been compressed using a distributed source coding method based on LDPC and Turbo codes. Instead of encrypting the entire video stream bit by bit, we encrypt only the highly sensitive bits. By combining the compression and encryption tasks and thus reducing the number of bits encrypted, we can achieve a reduction in system complexity.; Secure multicast protocols are difficult to implement efficiently due to the dynamic nature of the multicast group and scarcity of bandwidth at the receiving and transmitting ends. Mobility is one of the most distinct features to be considered in a wireless network. Moving users onto the key tree causes extra key management resources even though they are still in service. To take care of frequent handoff between wireless access networks, it is necessary to reduce the number of rekeying messages and the size of the messages. In this dissertation, we design a key management tree such that neighbors on the key tree are also physical neighbors on the cellular network. By tracking the user location, we localize the delivery of rekeying messages to the users who need them. This lessens the amount of traffic in wireless and wired intervals of the network. The group key management scheme uses a pre-positioned secret sharing scheme.