On the security of a class of diffusion mechanisms for image encryption
This work exposes a critical vulnerability in widely used image cryptosystems, potentially compromising their security for applications requiring fast and strong encryption.
The paper investigates the security of a class of diffusion mechanisms used in image encryption based on chaotic or quantum phenomena, finding that each element of the equivalent secret key can be recovered with only O(1) data complexity under plaintext attacks.
The need for fast and strong image cryptosystems motivates researchers to develop new techniques to apply traditional cryptographic primitives in order to exploit the intrinsic features of digital images. One of the most popular and mature technique is the use of complex ynamic phenomena, including chaotic orbits and quantum walks, to generate the required key stream. In this paper, under the assumption of plaintext attacks we investigate the security of a classic diffusion mechanism (and of its variants) used as the core cryptographic rimitive in some image cryptosystems based on the aforementioned complex dynamic phenomena. We have theoretically found that regardless of the key schedule process, the data complexity for recovering each element of the equivalent secret key from these diffusion mechanisms is only O(1). The proposed analysis is validated by means of numerical examples. Some additional cryptographic applications of our work are also discussed.