Multimedia is one of the most popular data transmitted over mobile and wireless communication channels. Image encryption is often achieved by using one of three approaches; traditional, selective, or in-compression encryption techniques. The most suitable one for multimedia encryption approach is the in-compression encryption approach since it has the advantages of both traditional and selective techniques. In this book, a new in-compression encryption technique for efficient and secure multimedia transmission is proposed. It is a general-purpose technique meaning that it can be used with any bit-string. It depends on a statistical model of the images to be encrypted and compressed to generate Optimized Multiple Huffman Tables (OMHT). These tables are used to encode-encrypt the compressed image according to a secret order (secret key). Only receivers that have the secret key can decode/decrypt the received bit stream. The effectiveness of this scheme is verified through a series of experiments, and the robustness of developed approach is demonstrated by comparing its performance with those of the traditional,and selective techniques.