Cryptanalysis of a chaos-based image encryption algorithm

Abstract

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A Modified Chaos-Based Image Encryption Algorithm

“…1) The secret keys of original algorithm are parameters p, q, n of Arnold cat map and initial values x 0 , y 0 , z 0 of Chen's chaotic system, the encryption steps are as follows: 2) The image firstly be shuffled by Arnold cat map as (2), then the shuffled image is converted into a sequence S; 3) A pseudo random key sequence K is produced by Chen's chaotic system (4) subsequently. Using K to do bitwise XOR operation with S, the encrypted sequence C can be produced as:…”

“…The scheme can't resist chosen-plaintext attack and known-plaintext attack, Cokal and Solak gave a complete break to it in [2]. Based on the scheme in [1], we propose a modified scheme which can resist both attacks by simply increasing one key and N horizontal-shifts.…”

“…In fact, many image encryption algorithms [1], [3]- [5] have weak ability of resisting differential attack [2], [6]- [8]. The conventional improved solution is increasing the rounds of encryption, but it will undoubtedly increase the running time and computational complexity.…”

Fast Adaptive Image Encryption using Chaos by Dynamic State Variables Selection

“…Then pixel values are modified sequentially using pseudorandom key stream elements produced by a certain qualified chaotic map in the diffusion procedure. This architecture forms the basis of numerous chaos-based image crypto-systems proposed subsequently [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Meanwhile, recent cryptanalysis works have demonstrated that some chaos-based image cryptosystems are insecure against various attacks, and have been successfully broken [14][15][16][17][18][19][20].…”

“…That means identical key stream will be used to encrypt different plain images if the secret key remains unchanged. This property allows the attacker to launch known-plaintext attack [30][31][32][33]35] or chosen-plaintext attack [17,18,19,20,21] so as to retrieve the equivalent key stream elements. Therefore, to further enhance the security, the key stream elements extracted from the same secret key should better be distinct and related to the plain image [22] the present paper proposes a novel chaos-based image encryption scheme with a dynamic state variables selection mechanism (DSVSM).…”