1.5.5 Hongjun W. 
A paper under the title. “A New Stream Cipher HC-256”.presents a new stream cipher HC-256. This stream cipher generates keystream from a 256-bit secret key and a 256-bit initialization vector. HC-256 consists of two secret tables, each one with 1024 32-bit elements. The two tables are used as S-Box alternatively. At each step one element of a table is updated and one 32-bit output is generated. At each step updating one element of a table with non-linear feedback function. Every 2048 steps all the elements of the two tables are updated. At each step, HC-256 generates one 32-bit output using the 32-bit-to-32-bit mapping similar to that being used in Blowfish. HC-256 is suitable for the modern (and future) superscalar microprocessors.
1.6 The Aim of Thesis
The general objective of this thesis is to modify the Rc4 stream cipher algorithm by using irreducible polynomial to increase the efficiency and security of the work and decrease the execution time.
1.7 Outline of the Thesis
This work begins with an introduction to the basic concepts of cryptography, which is relevant to the present work.
Chapter2: "Basic concepts of Cryptography and Stream Cipher", describes the basic terms and concepts of cryptography. It shows in detail the Rc4 stream cipher algorithm and the irreducible polynomial. At the end of this chapter the random bit generation tests are explained.
Chapter3: “The Proposed System Design", explains in detail the design…