Authors:
George Teşeleanu
1
;
2
Affiliations:
1
Advanced Technologies Institute, 10 Dinu Vintilă, Bucharest, Romania
;
2
Simion Stoilow Institute of Mathematics of the Romanian Academy, 21 Calea Grivitei, Bucharest, Romania
Keyword(s):
Image Encryption Scheme, Chaos Based Encryption, Cryptanalysis.
Abstract:
In 2022, Hosny et al. introduce an image encryption scheme that employs a fractional-order chaotic system. Their approach uses the hyper-chaotic system to generate the system’s main parameter, namely a secret permutation which is dependent on the size and the sum of the pixels of the source image. According to the authors, their scheme offers adequate security (i.e. 498 bits) for transmitting color images over unsecured channels. Nevertheless, in this paper we show that the scheme’s security is independent on the secret parameters used to initialize the hyper-chaotic system. More precisely, we provide a chosen plaintext/ciphertext attack whose complexity is O(6(WH)2) and needs WH oracle queries, where W and H are the width and the height of the encrypted image. For example, for an image of size 4000×3000 (12 megapixels image) we obtain a security margin of 49.61 bits, which is 10 times lower than the claimed bound.