An Approach for Secret Communication Using Adaptive Key Technique for Gray Scale Images

This work describes an adaptive key technique to hide data in an image. In Stage I, an encryption key has been generated to encrypt an envelope image. The length of the key has been adjusted with respect to size of an image and number of bits required to represent every pixel. In stage II, the encoding key has been generated with respect to size of the message. The key length has been calculated based on number of characters and equivalent bits to represent it. The encoding key encodes the message and its length. Stage III used to superimpose encoded data on encrypted image using data hider. In receiver side, the subsequent process carried out to decrypt image and decoding the data using same methodology that was adapted in the transmitter side. This work carried out for gray scale image and achieves good embedding capacity of 3bpp and also achieves good withstanding capability against to Steganalysis.