Encrypted Biography of Biomedical Image - a Pentalayer Cryptosystem on FPGA

Secure transmission of medical information occupies a crucial role in the world of telemedicine applications. Reconfigurable hardware implementation offers several advantages over software implementation especially for real time security applications. This work aims to propose the novel implementation of a penta-layer medical image encryption using a reconfigurable Cyclone II Field Programmable Gate Array (FPGA) EP2C35F672C6. The first layer of encryption performs the row-wise and column-wise pixel permutations based on Linear Feedback Shift Register (LFSR). The second and third layers of encryption are based on maximal length sequence Pseudo Random Number Generator (PRNG) 16-bit Cellular automata (CA) circuit and Galois Field (GF) product. In the fourth layer, a synthetic image is subsequently created by chaotic clock with Phase Lock Loop (PLLs) and gates to diffuse the image pixels. This creation of synthetic image for diffusion makes the developed cryptosystem totally hardware dependent. Last layer performs the diffusion using one dimensional logistic map. The synthesized result reveals that the reconfigurable implementation of proposed encryption process consumes comparatively lesser logic elements (2480) and low power consumption (278.65 mW) with an encryption time of 215.92 ms for encrypting a 256 × 256 DICOM medical image. Finally, various analyses such as Number of Pixel Change Rate (NPCR), Unified Average Change in Intensity (UACI), Entropy, Correlation, Uniform distribution and NIST statistical test suite have been performed to prove the robustness of the algorithm against various attacks.