Abstract. In this paper, a new approach of image steganography using two-dimensional Cellular Automata (2D-CA) has been proposed for a confidential message. We convert the message in such a way that message length becomes 1024 bits after padding some bits. If message size is more than 1024 bits, we subdivide the message of length 1024 bits using padding technique. Convert original message by XORing with shared secret key of length 1024 bits. Update the central pixel value of 3x3 2D-CA (rule 341) depending upon the parity (Odd or Even) of Least Significant Bits (LSB) of the cover work and converted bits of confidential message. During decoding only consider CA 341 rule and parity of LSB of stego image. XORing of decoded message and shared secret key, we can get the message of 1024 bits and combine different message component to get the original message. Results are compared with the Discrete Wavelet Transform (DWT) based steganography schemes in terms of Peak Signal-to-Noise Ratio (PSNR). This Image Steganography based on Cellular Automata (ISCA) method increases embedding capacity of confidential message. The security is measure by calculating the relative entropy between the probability distributions of the cover and stego image.

Received: January 10, 2013

AMS Subject Classification: 60A05

Key Words and Phrases: two-dimensional cellular automata (2D-CA), cover work, shared secret key, discrete wavelet transform (DWT), image steganography based on cellular automata (ISCA), least significant bit (LSB), peak signal-to-noise ratio (PSNR)

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