Cover G for 3 and 4 G-A Stego Product

The use of information over internet and our dependence on the computing machines has drastically increased with the advancements in technology. As a result, the storage and transmission of the ever increasing volumes of data in an effective way has become a high priority issue. The very systems which are boon to us are also being misused by many to cause harm. Thus, security is a major issue as far as the information is concerned. Thus, it becomes the responsibility of the parties involved in secret communication to arrange for the necessary security, preventing the sniffing by rogue entities. Advancement in digital communication technology along with internet makes data transfer easy and vulnerable to interception and modification by sneakers. Cryptography and steganography are ways of encrypting and hiding data. While Cryptography hides the essence of the data under a cover, like an encrypted text or periodic noises in a digital signal, steganography hides the fact of data itself. The information is more secure when both these techniques are used together. That is, even if the hidden information is found out, it will be encrypted. In this paper, it is proposed to explore the cover generation method. It uses information as data on covers like Image-cover, Circuit-cover Graph-cover, Chess-cover and Questionnaire etc and does not produce noise. Thus, noiseless steganography (noistega) is a fruitful option for data transmission in secured manner.

INTRODUCTION

Ever since the advent of life on earth, there has been the need for communication among the living beings for their own existence. When communication evolved, evolved the need to secure it. This need to secure information became more with the evolution of the internet, which shrunk the world into a global village. There are two types of information security. They are cryptography (Schneier, 2007) and steganography (Amirtharajan and Balaguru, 2009; Amirtharajan et al., 2010, 2011, 2012). Cryptography aims at hiding the information in a data, while steganography aims at hiding the data itself. The integrity of the information is higher when both these techniques are used together. Steganography is implemented in any digital media like audio, video, text and images of which image steganography has good reputation in the recent past (Hmood et al., 2010a, b; Amirtharajan and Rayappan, 2012a; b). In image steganography, the confidential information in a cover object i.e., image with immense skill resulting in the stego object (Amirtharajan et al., 2012). The confidential data that is embedded should possess good quality in order to make it imperceptible (Zanganeh and Ibrahim, 2011). Furthermore, the technique employed should offer high payload by the diligent embedding of more data in a given cover image.

Three main protection techniques include the cryptography, Steganography and watermark technology (Stefan and Fabin, 2000; Cheddad et al., 2010 ). The first one aims at providing copyright protection by embedding information which would authenticate the owner. While cryptography scrambles the data beyond immediate understanding, Steganography hides the data in images and text which cannot be detected (Rajagopalan et al., 2012). These two when combined provide higher security compared when each is used separately (Zaidan et al., 2010). This is because the detection of hidden information is itself a tedious task. Even if its detected, decrypting the message will pose another time consuming problem. Cryptography and Steganography when put together will enhance further security (Janakiraman et al., 2012a, b). The former involves the process of encryption and decryption and the latter involves embedding of information. Steganography is an ancient art to hide information in ways that prevent the detection of the hidden message. The media employed here are video, image, text, audio, binary etc. The digital signal processing is gaining more importance as they are easy to transmit. But the security involved is very poor resulting in hacking of useful information thereby creating noise in transmission. The steganography is the solution for this as it employs hiding of data through several ways. The three main elements of a Steganography system are Cover image, stego image and embedded image (Zanganeh and Ibrahim, 2011 ). To explain with an analogy, we used to post letters to an intended destination. Here, the content what we write is the information to be hidden (message), the packet into which the secret information is put into is termed as the cover and the final sealed information is called the Embedded message. This notion is presented in Fig. 1 in which the secret message is buried in the cover object to produce the final output called stego object.

The encoding is done in such a way that it is known only to the sender and receiver without being known to the third party. There exist several mechanisms to offer steganography. The simple classification is based on the type of covers. In Image-Binary, gray, color are the options.

In Audio, Video (Al-Frajat et al., 2010) and text (Shirali-Shahreza and Shirali-Shahreza, 2008 ) According to the cover modifications it could be further classified into 6 categories. Substitution based, Transform domain based, Spread Spectrum based, Statistical Methods based, Distortion based techniques and Cover generation based methods (Desoky 2008, 2010, 2011; Desoky and Younis. 2008, 2009). This study focuses more on cover generation methods.

Review on literature: Noistega can be of textual, image, audio in nature (Desoky, 2008).

In textual, comparison is made between original texts with the modified text to reveal the hidden information. The changes can be in font size, colour, spaces and misspellings and thus the data is embedded (Desoky, 2008).

Fig. 1:	General approach of a stego system

In image type (Janakiraman et al., 2012a, b; Thanikaiselvan et al., 2011a, b and Padmaa et al., 2011), the messages can be embedded in image depending upon the image size. But in this, the counterpart is subjected to distortion and destruction thereby limiting its usage for long distances. In audio type (Zhu et al., 2011), the text to speech software’s are employed thereby hiding is possible through spread spectrum coding (Thenmozhi et al., 2012), phase coding and echo hiding. Thus, steganography is an ocean which can be utilised depending on the user’s need. The following describes this steganography as:

The architecture and the working process for every type are explained in detail.

MATERIALS AND METHODS

Image stega:Cover based Steganography techniques are very useful in hiding the information in deceivingly innocent covers. For instance consider the example presented in Fig. 2. The image seems to consist of only some random images of flowers and by seeing it for the first time, one cannot predict that secret information is hidden in it. It need not be of same pattern.

Like one presented here. This is so because it may cause suspicion for the invaders. The more the random and ergodic the choice of cover(s), greater preserved the secrecy. Moreover, such choice does not give even a clue about what is hidden in there.

Fig. 2:	Example for image stega

Methodology:

Explanation: The secret word is hidden in the cover in the form of the consecutive alphabets of all the names, for example, the first letter ‘s’ from Solidaster, second letter ‘e’ from Kerria and so on. Thus by decoding in this way, the secret hidden is decoded as SECURITY. This is a very effective cover generation method.

The cover object is shown in Fig. 3 carries hidden information. When the picture is shown as such, the hackers other than the intended recipients will never get an idea of what the picture reveals. The corresponding Stego object is obtained by taking every second letter from each word and combining them, which reveals the word, “Security”. It proves to be a good method of hiding secret information. It improves the security and the visibility to decrypt the information.

The stego object is shown below:

Circuit stega: Another form of cover generation method is circuit Steganography. In this method, the ASCII values of the characters of the secret message are given as the values for the resistors, capacitors and other components present in the circuit.

Fig. 3:	Hidden message (“Security”) in stego object

Thus, unless it is known by a third party that the values correspond to a secret message, it will not be deciphered.

Methodology:

Explanation: The circuit in Fig. 4 shows hidden information, ‘security’. Each character of this word is converted to its equivalent ASCII value as follows:

S-115, E-101, C-99, U-117, R-114, I-105, T-116, Y-121

It is an efficient cum less-suspicion-captivating means to hide confidential information. One cannot have even an idea about veiling messages in a circuit. More information can be rooted when the circuits are employed are complex and bigger.

Graphstega: It is the form of Graph Steganography Methodology (Desoky and Younis, 2008). It does not embed message in the noise rather it does hiding of data as data points in the graph.

Fig. 4:	Circuit stega example (hidden message-security)

Thus this graph cover uses electronic and non-electronic format which makes hacking very difficult. A variant has been proposed.

Methodology:

Explanation: In this graphstega, the text is converted into a group of strings. It is then partitioned into a group of bits and a decimal representation is produced for every group.

The following explains the hiding of the message: “security”.

ASCII equivalent of the above word is:

115, 101, 99, 117, 114, 105, 116, 121

and these values are plotted in a graph to obtain this Steganographic method.

In the above, the plain text is encoded without affecting the correctness of it. Now MS-EXCEL is used to generate graph cover as follows:

This Steganographic method shows the secret message ‘security’ written in its ASCII form is plotted in a graph shown in Fig. 5 to remain concealed. This means promises elevated security as there is countless pattern of graphs which are put to use nowadays. As per the information to be hidden, the pattern of graphs can be chosen.

Fig. 5:	Secret message “security” hidden in graph cover

Graphstega is capable of handling both the short and long messages. For short messages the encoded values are the data plotted in the graph. Inspection of the graph is very easy. For long messages, values cannot be read from the graph so easily because of the scale constraints. For that, data are considered as the part of objects in the graph cover for retrieving the data. Example is that attaching an excel file in an email message.

Thus, graphstega is effective to camouflage every sort of data as mentioned by Desoky and Younis (2008).

Conversion techniques
Presenting data in image cover:The graph is converted into image formats like .jpg, .bmp. Here also the message is concealed as data values rather than pixels in image steganography, thereby reducing noise. It is unfit for large messages because the data should not exceed the prescribed size of the image.

Presenting data in text cover: Here, the encoded message is mixed up with some other texts and it is transmitted. It is explained in the following table.

In this graph cover, the encoded message is given as the prices of the books.

In the same way, we can produce graph cover as Tracking Number:

5790-152-21-1-53-861-055729-44-3867-1

Presenting data in audio cover: The data is encoded and then converted into audio using “text to speech” software. But the data is exposed to distortion and destruction.

The Graphstega could be implemented using MS-Excel and it is merely a tedious job to extract or hack data from the graph thereby enabling a graphstega, a successful technique in steganographic process.

Edustega: Education-centric steganography methodology.

It is a novel linguistic steganography methodology, which camouflages the data by manipulation. It includes the method of “question and answers” (Desoky, 2008; Xiang et al., 2011). Edu cover may be a pdf file, MS-word, even an image enabling the recipient to extract the hidden data. A variant has been proposed.

Methodology:

Table 1 illustrates the hiding of word ‘security’. The ASCII equivalent of this word is 115, 101, 99, 117, 114, 105, 116, 121 which is listed the price of various books. Figure 6 explains the Edustega modules and their interfacing. The Edustega is explained as shown:

In these, we have to take the first letter of the correct answer. Then we need to take the previous letter of the correct one. The first letter of the correct values will be “tizbnljsteib”. Now the letter previous to each will be “shyamkirubha”.

This is the correct value what we wish to transmit. But before this transmission, sender and receiver has to agree on the fact that they should take the previous value of the correct one. Thus, Edustega is one of the commonly used steganography methods for camouflaging datas by manipulating in terms of questions and answers. As this educational field draws people attention, many researches are being developed in this area (Desoky, 2011).

Chestega:

The following illustrates Chestega having chessboard as a criteria.

Assume that now the intension is to hide the content “shyamkirubha”. The 8 bit representation of this:

0111001101101000011110010110000101101101011010
11011010010111001001110101011000
100110100001100001

Table 1:	Secret information is hidden in “Price” column

Fig. 6:	Interfacing of Edu stega modules

It is then grouped as 7 digits and the corresponding decimal values are:

57, 90, 15, 22, 11, 53, 86, 105, 57, 29, 44, 38, 67, 1

The squares are encoded from 0 (in binary 0000000) to 127 (in binary 1111111). Employing an index that starts at 1 referring to 0 in decimal (in binary 0000000) up to 128 referring to 127 in decimal (in binary 1111111).

Figure 7 illustrates the white side and black side blocks after the secret message is buried. Table 2 explains how the bits are allotted in particular position.

While playing, the players will notice the moves and the corresponding decoding part is done and thus the data “shyamkirubha” is reached at the receiver side.

Fig. 7(a-b):	Representation of secret in (a) White and (b) Black side blocks

In this way, Chestega can be employed for camouflaging the important information. The below example is for Chestega using players name as parameters: The data are taken from the chess master database. In this, binary values are assigned for the every first letter of the player name. The corresponding decimal values are calculated.

By using this, we can hide the data as we know the corresponding binary and decimal values for every first letter of the player name.

It legitimizes the interactions between the sender and recipient based on their interest in chess games. Therefore, the hacking will be difficult as the deal is made between the users, as they know how to hide the information. Thus, this Chestega can be used to convey long messages also as mentioned in Desoky and Younis (2009). Table 3 gives the performance evaluation of all the proposed stego methods. All the metrics of performance are convincingly satisfied and thus justify their creation.

CONCLUSION

To summarize, this cover generation based steganography the critical data is camouflaged in any created cover object. In this study, five such cover generation based steganography has been explained with necessary illustrations. Among all, Image Stega, Circuit Stega would never raise any suspicion to the normal users. The rest Graphstega, Edustega and Chestega would offer better payload. Robustness, imperceptibility and capacity is good for all the described methods.

Table 2:	Allocation methodology in chestega

Table 3:	Performance analysis

ACKNOWLEDGMENT

Authors wish to appreciate Shyamkirubha for her earlier work on cover generation based steganography.