Options available for speech encryption

This paper presents two of the options available for speech encryption. The first is an analogue technique utilizing the principle of time element scrambling but introducing the concept of a sliding window. It is shown that this enables the system time delay to be reduced while simultaneously increasing the number of scrambling permutations available to the user. The second option is a digital technique using a stream cipher. Some of the requirements for such a system are discussed. Finally, the author attempts to show where these two options fit into the range of currently available techniques, from a security viewpoint.