Saroj Kumar Lenka

Steganography using two sided, three sided, and four sided side match methods

In this paper the two sided, three sided and four sided side match steganography methods are proposed. In two sided side match method the two neighboring pixels such as upper and upper-right corner are exploited to take embedding decision. In three sided side match method the three neighboring pixels such as upper, upper-right corner and upper-left corner are exploited to take embedding decision. In four sided side match method the four neighboring pixels such as upper, left, upper-right corner and upper-left corner are exploited to take embedding decision. In each of these methods the fall off boundary problem (FOBP) and fall in error problem (FIEP) are addressed. The FOBP and FIEP conditions are checked while embedding at the sender and while extracting at the receiver. These methods possess large hiding capacity, better imperceptibility and high security.

LSB Array Based Image Steganography Technique by Exploring the Four Least Significant Bits

In this paper a new LSB (least significant bit) array based image steganographic technique using encryption by RSA algorithm is proposed. In the image each pixel is 8 bits. The four arrays, namely the LSB, LSB1, LSB2 and LSB3 are formulated separately by collecting the bits from the 8th (LSB), 7th, 6th and 5th bit locations of the pixels respectively. The cipher text is divided into four blocks. The first block is mapped and slided over the LSB array and embedded at maximum matching portion of LSB array. Similarly the second, third and fourth blocks are embedded at maximum matching portion of LSB1, LSB2 and LSB3 arrays respectively. Where the blocks are embedded, the start indices are captured and embedded at a separate place in the image. The retrieving process at the receiver is the reverse of the sender. The performance of this technique is compared with other techniques.

A novel steganography technique by mapping words with LSB array

In this paper a new steganographic technique based on LSB array is proposed. Four LSB arrays such as LSB0, LSB1, LSB2 and LSB3 are defined. One of the four arrays is opted and formed depending upon the length of the secret message. For longer messages LSB3 array can be chosen. The different words of the secret message are mapped on the chosen array, where maximum match occurs, there steganographed and start indices are noted down. Once a word is embedded in a portion of the array, that portion is made unavailable for subsequent words. The length of each word and their start indices altogether are encrypted by RSA algorithm. The cipher text obtained is compressed and then embedded at some reserved location in the image. This reserved location was not used in forming the used LSB array. The experimental results confirm the strength of this technique.

A Better RGB Channel Based Image Steganography Technique

In this paper a new RGB channel based steganographic technique is proposed. The RSA algorithm is used for encryption and decryption. In a RGB image each pixel (24 bits) is having R-channel 8 bits, G-channel 8 bits and B-channel 8 bits. R, G and B stands for red, green and blue respectively. Out of these three channels, the one which is having the maximum value summed over for all the pixels will be decided as the indicator channel. Out of the remaining two channels (say channel1 and channel2) in each pixel, one channel is used for embedding four bits of the cipher text, depending on its value satisfying one of the four defined conditions. At the receiver side the reverse operation will be performed to retrieve the message. The experimental results show that the performance of this technique is satisfactory.

Steganography using the twelve square substitution cipher and an index variable

In this paper we are proposing a technique for secret communication between Alice and Bob. We are using both cryptography and steganography. Firstly, we encrypt the secret message using our new cipher algorithm called twelve square substitution cipher algorithm, and then embed the cipher text in the carrier image in 6th and 7th bit locations or 7th and 8th bit locations or 6 and 8 bit locations of the different pixels (bytes) of the carrier image depending on the value of an index variable. Here the 8 bit means the least significant bit (LSB) location, the 7 bit means the LSB minus one location and the 6 bit means the LSB minus two location. The index variable value can be 0 or 1 or 2. The index variable value will change from 0 to 1 or 1 to 2 or 2 to 0 after each embedding. The initial value of the index variable depends upon the length of the cipher text. After embedding the resultant image should be sent to the receiver and receiver should retrieve the cipher text from the said locations and then decrypt by using the twelve square cipher algorithm to get the secret message. The embedding locations are not same in all pixels, so it is a stronger approach. The algorithm is implemented using Java programming language. The experimental results says that the algorithm performs well.

A Dynamic Approach to Image Steganography Using the Three Least Significant Bits and Extended Hill Cipher

In this paper we propose a technique for secure communication between sender and receiver. We use both cryptography and steganography. We take image as the carrier to use steganography. We have extended the existing hill cipher to increase its robustness and used it as our cryptography algorithm. By using this extended hill cipher (a new block cipher) which uses a 128 bit key, we encrypt the secret message. Then the cipher text of the secret message is embedded into the carrier image in 6th, 7th and 8th bit locations of some of the selected pixels (bytes). The 8th bit in a pixel (byte) is called as the least significant bit (LSB). The pixel selection is done depending on the bit pattern of the cipher text. So for different messages the embedding pixels will be different. That means to know the pixels of the image where the cipher text is embedded we should know the cipher text bits. Thus it becomes a stronger steganography. As the pixels where we embed are chosen during the run time of the algorithm, so we say that it is dynamic steganography. After embedding the resultant image will be sent to the receiver, the receiver will apply the reverse process what the sender has done and get the secret message.

Pixel value differencing steganography using correlation of target pixel with neighboring pixels

This paper presents a steganograhpic technique based on the correlation of a target pixel with its neighboring pixels. There are four schemes; (i) five neighbor correlation, (ii) six neighbor correlation, (iii) seven neighbor correlation, and (iv) eight neighbor correlation. In five neighbor correlation scheme the difference between the target pixel value and the average of the five neighboring pixel values is calculated to estimate the number of bits that can be embedded in the target pixel. Similarly, in six, seven, and eight neighbor correlation schemes the difference between the target pixel value and the average of the six, seven and eight neighboring pixel values respectively is calculated to estimate the number of bits that can be embedded in the target pixel. The experimental results reveal that no visual marks can be observed at the stego-images. The estimated peak signal-to-noise ratio values in the stego-images are higher as compared to that of the existing two, three, and four sided side match schemes. The extraction procedure is very simple and does not require the original image to retrieve the message from the stego-image.

A Robust Image Steganography Technique Using Dynamic Embedding with Two Least Significant Bits

In this paper we are proposing a new Image steganography technique for secure communication between sender and receiver. At the sender we follow two steps. In the first step we encrypt the secret information by blowfish algorithm and in second step we embed the cipher text in LSB minus one and LSB (least significant bit) locations of some of the selected pixels (bytes) of the carrier image. One pixel is 8 bits in 8-bit gray scale. The selection of the pixels is done by a dynamic evaluation function. Depending on the cipher text bits, the dynamic evaluation function decides on which pixels the different cipher text bits are to be embedded. At the receiver also two steps are followed, first the cipher bits are retrieved from the image from the said locations and then it is decrypted by using the blowfish algorithm to get the secret information. As the embedding byte locations are decided based on bits of the cipher text, so it is dynamic steganography. This approach provides two levels of security, one at the cryptography level and the other at the steganography level. The proposed technique is experimented through a large number of experiments.