Variable Bits Secure System for Color Images

摘要

This paper proposes an RGB-based, secure technique to maintain and authenticate the integrity of a document. The novel Steganographic algorithm that we have proposed has its strength greatly enhanced by use of hybrid cryptography on data that is to be hidden in cover image. The secret message is converted into two kinds of plaintexts by subsequent ASCII and binary conversions and suitable bit stuffing. Two cipher texts are obtained using RSA and IDEA algorithms, which make up for a hybrid crypto-system. Both of these cipher texts are hidden in the cover image of the note using our novel, variable-length lSB-based Steganographic technique for data hiding in RGB images. One cipher text is used to determine the position for data hiding and the other cipher text is hidden in the lSBs of the color channel (that have minimum color contribution in the image) of the chosen pixels using variable length lSB based data embedding. Maximum intensity color channel is used to indicate which minimum intensity channel has how many bits of data embedded in it. We define the indicator and data channels from among the RGB color channels and use them for hiding of respective data in the cover image. Choosing such channels for hiding indicator and data bits, causes minimum distortion in the color of the pixels and such changes go undetected by Human Vision System (HVS).