Steganography Using BCH-Codes

Abstract

The improvement of the internet sources makes peoples bit by bit familiar with the computerized data through different systems. It is frequently evidence that an expensive piece of this information is either classified or private. Therefore, extraordinary security procedure has been used to give the required protection. So the issues of security and privacy have usually been approached using tools from cryptography. The message can be attached with a message authentication code (hash) and encrypted so that only the rightful recipient can read them and verify their integrity and authenticity. Modern cryptography is a developing field based on a demand mathematical foundation and decades of development. Encrypted messages are obvious, and when a message is intercepted it is clear that the sender and recipient are communicating secretly. Steganography is the little and much younger sister of cryptography. It is an alternative tool for privacy and security. Instead of encrypting messages, we can hide them in other innocent looking objects so that their very presence is not exposed [24]. Thus, steganography can be a feasible alternative in countries where usage of encryption is illegal or in oppressive commands where using cryptography might attract unwanted attention. A recent example of a practical steganographic scheme that was used for information exchange between two subjects, one of which was residing at the time in a hostile country, was described by Toby Sharp at the 4th information hiding workshop [1]. Coding theory is a branch of mathematics which deals with the problems of errors that happens to the message when it is transferred through some communication channels. The goal of coding theory is to offer secure communication of information, in the sense that errors that occurred during the transmission can be corrected. However, to enjoy the benefit of this property some value must be paid, this value is in the form of redundant bits which are added in the transmitting data. There are two purposes of utilizing error correcting codes in steganography. The first purpose is to secure the secret information which is loaded in some other medium from different attacks such as reencoding and compression. The second purpose of utilizing error correcting code is to use the syndrome coding for data embedding. The purpose of using syndrome coding for data embedding is to find those bits in the cover medium such that there is a minimum distortion in cover medium. Here is some related work regarding steganography and coding theory. In 2016 R J Mastafa utilize the concept of Discrete Cosine Transformation for video steganography along with BCH-Code [2]. For the increase in security of secret data, he encrypted the message first by using a key and then encoded with BCH (7,4,1) -Code. On the other hand, video is taken as a cover medium. Video is first converted into frames and then each frame is separated into Y, U, V components. The purpose of converting frames into Y, U, V space is to remove the correlation between colors, then the encoded message is embedded in these spaces. He uses BCH-Code prior to the embedding due to the motivation from the work of Liu et al [3]. Liu et al in his work discusses that (7,4,1) is the best code among the others. In 2014 Ramadhan J Mstafa and Khalad M Elleithy presented a video steganographic algorithm they used uncompressed video sequences as a cover media. Before embedding the secret message is encoded first using Hamming (7,4) Code then this encoded message is embedded into the cover video [4]. vii In 2009, Eltahir et al presented a video steganography based on the Least Significant Bit (LSB). Author tried to increase the size of the secret message into the video frames. Video frames are used as a still image. A 3-3-2 approach has been used which means taking the LSB of all RGB color components (3 bits of red, 3 bits of Green, and 2 bits of Blue) [5]. So from the review of these and other related work we have proposed a new algorithm, “Video steganography using BCH-Code”. Chapter wise introduction of the thesis work is listed below. In chapter: 1 we have discussed some basic definitions of cryptography and steganography, which are useful for understanding of proposed work. This chapter is divided into three sections. Section one, covers some basic definitions regarding cryptography. Section two, covers basic definitions about steganography and in section three we have discussed classifications of steganography. In chapter: 2 we have discussed some basic definitions of coding theory and its applications in steganography. We have split this chapter into two sections. Section one, covers some basic definitions regarding coding theory and particular BCH-Code. In section two applications of steganography are discussed. At the end some related work is discussed In chapter: 3 we have discussed proposed work in detail In this article we have used Least Significant Bit (LSB) method for video steganography along with BCH-Code. Video is used as a cover medium and an encrypted image/text is used as a secret message. Firstly, encrypted image/text is converted into binary string and then encoded using BCH-Code. On the other hand, video is converted into frames and some of these frames are selected using a pseudo random number. At the end this encoded binary strings are embedded using LSB in each pixel of R, G, B plane of selected frames. It is observed that the proposed algorithm has high embedding efficiency and is robust against data loss. Chapter:4 includes the conclusion of the work.