Title: An enhanced Hill cipher approach for image encryption in steganography

Authors: B. Karthikeyan; Jagannathan Chakravarthy; V. Vaithiyanathan

Addresses: School of Computing, SASTRA University, Thanjavur – 613401, Tamilnadu, India ' School of Electrical and Electronics Engineering, SASTRA University, Thanjavur – 613401, Tamilnadu, India ' School of Computing, SASTRA University, Thanjavur – 613401, Tamilnadu, India

Abstract: In this paper, a new approach is adopted to embed an image within an image using a modified Hill cipher method. The secret image is taken and rearranged to form N 2 × 2 matrices. A key matrix of length 2 × 2 is multiplied with all the N matrices and modulo-256 operation is performed. Then the new N matrices are rearranged to form a one-dimensional matrix. Each element of this matrix is converted to its binary value. A cover image is taken and in each of its pixels, the two least significant bits (LSB) are replaced with two bits from the binary matrix successively. While retrieving, the last 2 bits from each cover pixel are taken out, arranged to form a binary matrix and are converted into their respective 8-bit values. This one dimensional array is converted into N 2 × 2 matrices. These matrices are multiplied with the inverse of the key matrix to get the original values. These values are then rearranged appropriately to get the secret image which was transmitted.

Keywords: image encryption; decryption; steganography; enhanced Hill cipher; LSB substitution; least significant bits; cryptography; security; secret images.

DOI: 10.1504/IJESDF.2013.058652

International Journal of Electronic Security and Digital Forensics, 2013 Vol.5 No.3/4, pp.178 - 187

Received: 12 Jan 2013
Accepted: 01 Jul 2013
Published online: 26 Jul 2014 *

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