A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 1993

Huffman compression is one of the statistical compression mechanism, and is also a more simple algorithm than the others. Using the. dynamic tree coding and decoding, the compressor and expander can compress and expand the file easily. Because only when the probability of symbol's appearance is the integer power of 0.5, using Huffman compression can get a good efficiency. Since it is ·difficult to get such good situation, therefore, we combined the ideas of bit map and pattern substitution with Huffman algorithm, and made a little modification of them to implement two programs. Because of the characteristics of un-fixed length code encoded by Huffman way, the serial data can be decoded easily if the data is stolen on the transmission line. Therefore, in order to encourage the text transmission, we add an encryption, using bit cipher method after Huffman encoding, and using character cipher way to see if it will affect the compression efficiency. From the transmission viewpoint, we also have done a file communication experiment employing a software transfer package, named Telix. Our main purpose of this experiment is to compare the total efficiency of our programs with the software of others, such as Zip, Lzss, MNP-5, and so on.