Abstract—In the era of information technology, hospitals, medical centers, doctors and health specialists share millions of images. Securing these images is essential to maintaining patients’ privacy. Several cryptographic algorithms are implemented to meet the increasing demands of transmission systems. As a contribution to securing these data, we propose a novel robust and efficient algorithm. We randomly generate numbers from a six-dimensional hyperchaotic system and Arnold’s cat map to confuse the original images. The confused images are then diffused using a k-Fibonacci matrix. The performance of the proposed algorithm was evaluated using several parameters tested on a set of reference images of different sizes and modalities. The obtained results are conclusive and the performances are excellent, sometimes exceeding those found by other recent algorithms proposed in the literature.