This paper presents a novel approach of building a secure data hiding technique in digital images. The image steganography technique takes the advantage of limited power of human visual system (HVS). It uses image as cover media for embedding secret message. The most important requirement for a steganographic algorithm is to be imperceptible while maximizing the size of the payload. In this paper a method is proposed to encrypt the secret bits of the message based on chaos theory before embedding into the cover image. A 3-3-2 LSB insertion method has been used for image steganography. Experimental results show a substantial improvement in the Peak Signal to Noise Ratio (PSNR) and Image Fidelity (IF) value of the proposed technique over the base technique of 3-3-2 LSB insertion.

In this paper, a computational science guided soft computing based cryptographic technique using Ant Colony Intelligence (ACICT) has been proposed. In this proposed approach at first a metamorphosed based strategy is used to produce intermediate cipher text. Finally, ACI generated keystream is used to further encrypt the intermediate cipher text to produce the final cipher text. In this approach an ant agent having a pheromone deposition consisting of a group of alphanumeric characters is called a key stream and each character in the key stream is known as key. The key stream length always be less than or equal to the plaintext to be encrypt. The keystream generation is based on distribution of characters in the plaintext. Instead of transmitting the plain keystream to the receiver, further encryption is done on keystream and encrypted keystream get transmitted to the receiver. Parametric tests are done and results are compared with some existing classical techniques, which show comparable results for the proposed system.

In this paper, a Legendre transformation (LT) based fragile watermarking technique has been proposed for color image authentication. The authentication is done by inserting the watermark into the carrier images in transform domain. An initial pixel adjustment has been applied on each pixel component to keep the pixel value positive and less than or equal to the maximum. The Legendre transformation (LT) is applied on each pair of pixel components of the carrier image in row major order. The first transformed component can fabricate two bits whereas the second component fabricates three bits of authenticating watermark starting from the least significant bit position (LSB-0). A post adjustment is also applied to keep the embedded components closer to the original without affecting the least three significant bits. The inverse Legendre transform (ILT) is applied on each adjusted pair to re-generate the watermarked image. During inverse transform, at if the second pixel component of the adjusted pair become fractional, then the LSB-2of the first component is set to one; otherwise is set to zero. The reverse procedure is applied at the destination to retrieve back the watermark which in turn is verified for authentication through a message digest. Experimental results conform that the proposed algorithm has improvised the payload and PSNR over Varsaki et. al's Method [6] and LTCIA technique [7].

ABSTRACT

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