Confusion and diffusion are the frequently used embryonics in multimedia (image) encryption systems. Multimedia data protection against cryptanalysis can be effectually fortified by these techniques. Due to inherent properties of images such as high inter-pixel redundancy and bulk data capacity, encryption is performed in two stages: Confusion and Diffusion. In this article, a combined Pseudo Hadamard transformation in the confusion stage and Gingerbreadman chaotic substitution in the diffusion stage are used in the encryption phase of the algorithm. The strong correlation between contiguous elements in the host image is effectually reduced using Pseudo Hadamard transformation and entropy in the cipher image is enhanced using Gingerbreadman chaotic substitution. Secrete key length used in the algorithm is 128 bits, these are the initial conditions for Gingerbreadman chaotic generator. The elements of S-box in the substitution stage are considered from this random sequence generator. Experimental exploration including information entropy, correlation analysis, sensitivity analysis, key space analysis and computational complexity have been performed on set of standard images. Results obtained are better compared to many existing systems.
Optical alignment algorithm using Hadamard transformation
