In this paper, combined the encrypting and compressing processes to consider the choices of which types of bits are most effective in the selective encryption sense when they are changed. So, instead of encrypting the whole file bit by bit, changed only these highly sensitive bits. Moreover, by combining the compression and encryption tasks and reducing the total encryption work required, it will helps to achieve a savings in system complexity. Selective encryption is the technique of encrypting some parts of a compressed data file while leaving others unencrypted. Selective encryption is not a new idea. It has been proposed in several applications, especially in the commercial multimedia industry. Hover, selective encryption of lossless compressed text files has not been explored, and that is the focus of this paper.

Codeword encryption compression alphabet security frequency Huffman coding