Information hiding using stochastic diffusion for the covert transmission of encrypted images

A principal weakness of all encryption systems is that the output data can be ‘seen’ to be encrypted. In other words, encrypted data provides a ‘flag’ on the potential value of the information that has been encrypted. In this paper, we provide a novel approach to ‘hiding’ encrypted data in a digital image. We consider an approach in which a plaintext image is encrypted with a cipher using the processes of ‘stochastic diffusion’ and the output quantized into a 1-bit array generating a binary image cipher-text. This output is then ‘embedded’ in a host image which is undertaken either in the lowest 1-bit layer or multiple 1-bit layers. Decryption is accomplished by extracting the binary image from the host image and correlating the result with the original cipher. The approach has a variety of applications including: (i) covert transmission of encrypted images; (ii) authentication and self-authentication of e-documents that are assumed to be communicated over the Internet and are thereby vulnerable to attack (e.g. modification, editing, counterfeiting etc.). The paper includes an address from which interested readers can download a prototype system called StegoCrypt developed using the algorithms presented.