An approach for secured image encryption scheme using user defined operator based steganographic technique with pixels repositioning schemes

Steganography is the practice of concealing information of one object within other non secret object. We replace least significant bits from enveloped image with the bits of original image at the time of LSB based image steganography. This approach is not as secured as retrieving the least significant bits from the enveloped image will provide all the information of original image. So in the proposed system, we rearrange all the pixels of the original and the enveloped image using prime and non-prime positions of the pixels. Again we reposition all the pixels using one of the user defined pixel repositioning algorithms (PRONE (positional reverse odd normal even), PRENO (positional reverse even normal odd), CRENO (continuous reverse even normal odd), CRONE (continuous reverse odd normal even)) chosen by the user for original and enveloped image separately. Lastly we perform user defined BWMAS operation (Bitwise Masking & Alternate Sequence) between the bits of original image and the least significant bits of the enveloped image. As all the pixels of both enveloped and original images are repositioned, so the pixels from original image are chosen actually in non sequential manner and the pixels, taken from enveloped image for BWMAS operation are also in non sequential manner. Only the proper sequences of the encrypted pixels defined by the user defined algorithms are being able to retrieve the information of the original image. We introduce Bitwise Masking & Alternate Sequence operation for the first time in state of XOR operation. Thus an attempt is made to increase the security of the image encryption system.