Hybrid image crypto system for secure image communication- A VLSI approach

This work presents permutation and diffusion based hybrid image crypto system in transform domain using combined chaotic maps and Haar Integer Wavelet Transform (HIWT). HIWT is used to transform the plain image and four sub-bands of the image coefficients are encrypted by combined chaotic maps. The combination of two one-dimensional chaotic maps results in better chaotic behavior and generates unpredictable large random sequence that can be used for the encryption of the image. To manage the trade-offs between security, speed and power consumption, the proposed encryption algorithm is modeled in Cyclone II Field Programmable Gate Array (FPGA). The proposed design occupies only 4025 logical elements and takes 0.28 ms for encrypting an image of size 256 × 256. Robustness of the algorithm is estimated using quality metrics including statistical and differential attack analysis. The proposed scheme is resistant to most of the known attacks and is more secure than other image encryption schemes.