Musheer Ahmad

Key Dependent Image Steganography Using Edge Detection

Steganography is the science of invisible communication. It aims at hiding sensitive information in digital media in a way to conceal the existence of information. In this paper, we aimed to propose an improved secured image steganography scheme recently given by Chen et al. The improved scheme is secret key based random LSB substitution. It also takes the advantages of edge detection based pixel dependency to achieve high embedding data capacity. The experiment results show that the proposed scheme also achieves high embedding capacity. High scores of PSNR reveal that there is no noticeable difference between cover image and stego-image. Moreover, the proposed improved scheme is robust and can protect effectively the embedded message from being steganalysis due to the inception of randomness, pixel dependency and key dependency.

Digital image encryption based on chaotic map for secure transmission

In the past decade, a number of image encryption algorithms based on chaotic maps have been proposed. Recently, an image encryption algorithm based on chaotic map lattice (CML) is proposed that allows direct encryption and decryption of color digital images. In this paper, we propose an enhanced CML based algorithm for image encryption to improve the security of the algorithm. The performance of the proposed algorithm is analyzed through computer simulations. It is shown that the enhanced algorithm successfully and completely encrypts the color images and provides more distortion to the plainimages than previously proposed CML based algorithm for the same set of parameters. It is also shown that the proposed algorithm is more sensitive to a small change in plainimages, number of iterations and number of cycles. This makes the proposed algorithm more efficient and improves the level of security provided by the algorithm.

A Chaos Based Method for Efficient Cryptographic S-box Design

Substitution boxes are integral parts of most of the conventional block ciphering techniques such as DES, AES, IDEA, etc. The strengths of these encryption techniques solely depend upon the quality of their nonlinear S-boxes. Therefore, the construction of cryptographically strong S-boxes is always a challenge to build secure cryptosystems. In this paper, an efficient method for designing chaos-based cryptographic S-box is presented. The chaotically-modulated system trajectory of chaotic map is sampled and pretreated to generate an initial 8×8 S-box. Elements shuffling through random circular-rotation and zig-zag scan pattern are carried out to improve its quality. The experimental results of analyses such as bijectivity, nonlinearity, strict avalanche criterion, equiprobable input/output XOR distribution, etc., demonstrate that the proposed S-box has better cryptographic properties as compared to the recently proposed chaos-based S-boxes, which justify its effectiveness for the design of strong block cryptosystem.

Cryptanalysis of Image Encryption Algorithm Based on Pixel Shuffling and Chaotic S-box Transformation

Recently Hussain et al. proposed an image encryption algorithm which has three independent phases: (1) total pixel shuffling performed, in spatial domain, with permutation sequences extracted from chaotic skew tent map, (2) diffusion carried out using random codes generated from same chaotic map, and (3) extra confusion induced with substitution-box transformation. Though, the encryption algorithm achieves optimal scores of NPCR/UACI and exhibits great encryption strength. But, a careful analysis unveils its inherent security flaws, leaving it vulnerable to cryptographic attack. In this paper, we analyze its security weaknesses and proposed a chosen plaintext-attack with inverse S-box to break the algorithm completely. It is shown that the plain-image can be recovered successfully without knowing the secret key. The computer simulation of attack highlights the ineptness of Hussain et al. algorithm and shows that it is not commendable to deploy it for practical encryption of digital images.

A Simple and Efficient Key-Dependent S-Box Design Using Fisher-Yates Shuffle Technique

The substitution boxes are the only components in most of symmetric encryption systems that induce nonlinearity to provide efficacious data confusion. The cryptographic potency of these systems primarily depends upon the caliber of their S-boxes. This brings new challenges to design cryptographically efficient S-boxes to develop strong encryption systems. Here, a simple and effective method to design an efficient 8×8 S-box is put forward. The proposed design methodology is based on the classical Fisher-Yates shuffle technique. A piece-wise linear chaotic map is incorporated to act as a source to generate random numbers for proficient execution of shuffle technique. The construction of dynamic S-box is under the control of secret key. The performance evaluation of proposed S-box against standard statistical tests like bijective property, nonlinearity, strict avalanche criteria and equiprobable I/O XOR distribution reveals its excellent performance. Moreover, the proposed S-box is also compared with some recent chaos-based S-boxes. The investigations confirm that the design is consistent and suitable for secure communication.

Cryptanalysis of Chaos Based Secure Satellite Imagery Cryptosystem

Recently Usama et al. proposed a chaos-based satellite image cryptosystem, which employed multiple one-dimensional chaotic maps in novel manner to enhance the robustness, security and efficiency of sensitive satellite imagery. It is very efficient in terms of encryption time. The authors of the cryptosystem under study claimed that it has high level of security and can be applied to transmit confidential multimedia images over Internet/shared network. Unfortunately, the security analysis of the cryptosystem reveals that it has serious security flaws. Consequently, it is susceptible to a number of attacks. In this paper, the cryptanalysis of original cryptosystem is presented and it is shown that the attacker can recovers the plain-image from given cipher-image under three types of classical cryptographic attacks without knowing the secret key. The simulation results of cryptanalysis demonstrate that the cryptosystem highly lacks security and cannot be utilized for the protection of confidential/sensitive multimedia images such as the satellite imagery.

Cryptanalysis of Image Encryption Based on Permutation-Substitution Using Chaotic Map and Latin Square Image Cipher

Recently Panduranga et al. suggested an image encryption algorithm based on permutation-substitution architecture using chaotic map and Latin square. According to the proposal, the pixels of plain-image are firstly scrambled according to permutation vector, extracted from chaotic sequence, in permutation phase. In substitution phase, the permuted image is substituted by XOR operation with key image generated from a keyed Latin square. The algorithm has the ability to adapt and encrypt any plain-image with unequal width and height. Moreover, it also exhibits the features of high entropy, low pixels correlation, large key space, high key sensitivity, etc. However, a careful analysis of Panduranga et al. algorithm unveils few security flaws which make it susceptible to cryptographic attack. In this paper, we analyze its security and proposed a chosen plaintext-attack to break the algorithm completely. It is shown that the plain-image can be successfully recovered without knowing the secret key. The simulation of proposed attack demonstrates that Panduranga et al. algorithm is not at all secure for practical encryption of sensitive digital images.

Modified Multi-Chaotic Systems that are Based on Pixel Shuffle for Image Encryption

Abstract —Recently, a pixel-chaotic-shuffling (PCS) method has been proposed by Huang et al. for encrypting color images using multiple chaotic systems like the Henon, the Lorenz, the Chua, and the Rossler systems. All of which have great encryption performance. The authors claimed that their pixel-chaotic-shuffle (PCS) encryption method has high confidential security. However, the security analysis of the PCS method against the chosen-plaintext attack (CPA) and known-plaintext attack (KPA) performed by Solak et al. successfully breaks the PCS encryption scheme without knowing the secret key. In this paper we present an improved shuffling pattern for the plaintext image bits to make the cryptosystem proposed by Huang et al. resistant to chosen-plaintext attack and known-plaintext attack. The modifications in the existing PCS encryption method are proposed to improve its security performance against the potential attacks described above. The Number of Pixel Change Rate (NPCR), Unified Average Changed Intensity (UACI), information entropy, and correlation coefficient analysis are performed to evaluate the statistical performance of the modified PCS method. The simulation analysis reveals that the modified PCS method has better statistical features and is more resistant to attacks than Huang et al.’s PCS method.

A Multi-Level Blocks Scrambling Based Chaotic Image Cipher

In this paper, an image encryption scheme based on multi-level blocks scrambling is proposed. The image is first decomposed into non-overlapping blocks and scrambling of these blocks is done by using 2D Cat transform. Multi-level blocks scrambling (MLBS) is implemented by starting with a large block size and the size of blocks gets reduced iteratively at each level. The scrambling of blocks is performed at multiple levels to get cummulative effect. At each level, the control parameters of scrambling are randomly generated through 2D coupled Logistic map to make the process of scrambling key dependent. The scrambled image obtained after carrying out MLBS scrambling is encrypted using chaotic sequence generated by one-dimensional Logistic map. The experimental results show that the proposed encryption scheme can successfully encrypts/decrypts the images with same secret keys. The algorithm has large key space and high sensitivity to a small change in secret keys. The simulation analysis also demonstrates that the ciphered images have high information entropy, very low correlation coefficients and uniform gray level distribution.

Digital image authentication and encryption using digital signature

In this paper, a methodology for digital image authentication using digital signature is proposed. The hash of the original image is taken and is encrypted by RSA. The digital signature obtained is concealed in the image. Digital signature is sent along with the encrypted image which decreases the probability of meticulous attack by the intruder. The encrypted image is shuffled using Chaotic Logistic Map to get the final shuffled encrypted image. The use of Logistic Map improves the randomness in the image. For the authentication, a comparator is employed which evaluates correctness of the hash extracted. The simulations have been carried out to examine the proposed authentication and encryption technique.