Saurabh Dutta

An enhancement of security of image using permutation of RGB-components

Data bits from textual message are encrypted through key to some suitable nonlinear pixel and bit positions about the entire image. As a result, we get a watermarked image. After that we have formed three different image shares using any two components of R, G and B of entire watermarked image. The key is also divided into three different logical blocks by digits. By combining any two blocks of key we have formed key shares and have assigned to image shares. Out of those three shares, only addition of any two is able to make the full image or key. At the decryption end through appropriate arrangement of shares of key and image, make possible to retrieve hidden data bits from watermarked image and reform into its original content.

A Stream Cipher based Bit-Level Symmetric Key Cryptographic Technique using Chen Prime Number

In this paper, a stream cipher based symmetric key cryptographic technique based on Chen prime number has been proposed. The proposed technique is suitable for encryption and decryption of a large number of files of almost any type. A symmetric key is formed by the sender directly from the plain text using Chen prime number. Then a symmetric key value is derived from the symmetric key which is used to form the cipher text. The symmetric key is sent to the receiver by the sender. The symmetric key value is derived by the receiver from the symmetric key which is used for decryption. To enhance security, focus is to secure the symmetric key value rather than the symmetric key.

An Enhancement of Security on Image Applying Asymmetric Key Algorithm

characters of textual message are encrypted through the encryption key of RSA algorithm and then to an array of data bits. After that the data bits are embedded to some suitable nonlinear pixel and bit positions about the entire image through system modulus of RSA algorithm. As a result, we get a watermarked image. After that we have formed three different image shares using any two components of R, G and B of entire watermarked image. At the decryption end, three key shares are assigned for each and every share. The system modulus and private key are calculated from the prime factors of key shares. The embedded data bits are being retrieved from watermarked image by the system modulus and decrypted to the corresponding characters by the key, finally to its original content.

Secure Symmetric Key Transmission of Messages Using Random Shuffling of Spiral Matrix and Multiplicative Inverse (RSSMMI)

A bit level block cipher based symmetric key cryptographic technique is proposed here. Entire plaintext file reads two characters at a time and according to the binary representation of ASCII value of these characters, 16-bit blocks are created and they are represented in a 4 × 4 spiral matrix. Then using random shuffling of spiral matrix and multiplicative inverse, 8-bit ciphertext blocks are generated for each 16-bit plaintext block. So here 50% compression is achieved in terms of size of ciphertext file. Apart from compression, RSSMMI technique has several advantages like formation of symmetric key dynamically and randomly, security, and equal applicability of this technique for large number of files of almost any type.

Secure User Authentication System Using Image-Based OTP and Randomize Numeric OTP Based on User Unique Biometric Image and Digit Repositioning Scheme

Proposed system introduces a combined one time password (OTP)-based authentication system where image OTP is used in first level and numeric OTP is used in the second level of authentication. Server randomly selects an image as image OTP and encrypts it using user unique biometric image and user-defined Bit-wise Masking and Alternate Sequence (BWMAS) operation. This encrypted image OTP will be shared and to be decrypt by the user. Then the system generates a large random number as first part of numeric OTP within a range where range value is derived from the user password. Second part of numeric OTP is generated from the values of randomly selected blocks of the randomly selected pixels of user biometric image. Finally we combine those OTPs using alternate merging and generate intermediate numeric OTP which will be shared from server to user. Final numeric OTP will be generated in user and server end from intermediate OTP using user-defined digit repositioning scheme chosen by user. Random generation of numeric and image OTP, distribution of encrypted image OTP and formation of final numeric OTP using digit repositioning scheme impose a great security to the system.

A real time text steganalysis by using statistical method

Steganography is the art of hiding data in data in an untraceable way. Main concern of steganography is hiding the existence of hidden message. Steganalysis is the art and science of detecting hidden messages from stego-systems. It also attempts to find hidden message such as the type of embedding algorithm, the length of the message, the content of the message or the secret key used from the carrier (like image, text, video etc.). In this paper, we have discussed the steganalysis technique by using Bayesian Estimation and Correlation Coefficient based steganalysis methodologies for text.

An attempt to ensure security of payload by targeting non-linear seed pixel positions in carrier image

Data bits from textual message are encrypted through key to some suitable nonlinear seed pixel positions about the entire image. As a result, we get a watermarked image. After that we have formed three different image shares using any two components of R, G and B of entire watermarked image. The key is also divided into three different logical blocks by digits. By combining any two blocks of key we have formed key shares and have assigned to image shares. Out of those three shares, only addition of any two is able to make the full image or key. At the decryption end through appropriate arrangement of shares of key and image, make possible to retrieve hidden data bits from watermarked image and restructuring into its original content.