基于Logistic系统的图像模块混沌加密解密算法
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Chin. Phys. B Vol. 21, No. 6 (2012) 060502
Cryptanalysis on an image block encryption algorithm
based on spatiotemporal chaos
∗
Wang Xing-Yuan(王兴元)
†
and He Guo-Xiang(何国祥)
‡
Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024, China
(Received 9 August 2011; revised manuscript received 11 December 2011)
An image blo ck encryption scheme based on spatiotemporal chaos has been proposed recently. In this paper, we
analyse the security weakness of the proposal. The main problem of the original scheme is that the generated keystream
remains unchanged for encrypting every image. Based on the flaws, we demonstrate a chosen plaintext attack for
revealing the equivalent keys with only 6 pairs of plaintext/ciphertext used. Finally, experimental results show the
validity of our attack.
Keywords: encryption, spatiotemporal chaos, chosen plaintext attack, equivalent keys
PACS: 05.45.–a, 05.45.Ac, 05.45.Vx DOI: 10.1088/1674-1056/21/6/060502
1. Introduction
Chaos is a definitive and similar random pro-
cedure which appears in a nonlinear system.
[1−6]
A
chaotic system is characterized by sensitive depen-
dence on the initial conditions and control parame-
ters. Therefore, it has attracted much attention for
cryptology. In 1989, Matthews
[7]
first proposed the
chaos-based encryption scheme, and Fridrich
[8]
first
introduced the chaotic map into image encryption in
1997. Since then, many chaos-based image encryp-
tion algorithms have been designed to realize secure
communication through public channels.
However, most of these schemes are based on low-
dimensional chaotic maps,
[9,10]
whose drawbacks such
as small key space, weak security, and so on are obvi-
ous. Hence high-dimensional chaotic systems,
[11−13]
multiple chaotic systems,
[14,15]
and spatiotemporal
chaotic systems
[16−20]
have been proposed to improve
the security of chaos-based encryption schemes. Un-
fortunately, many of them have been found to be in-
secure.
In this paper, we analyse the image block encryp-
tion scheme based on spatiotemporal chaos proposed
recently in Ref. [19]. The cryptosystem first divides
the image into blocks, and then uses the block number
as the spatial parameter of coupled map lattice (CML)
to iterate the chaos system. The chaos sequence and
the former block plaintext co-determine the substitu-
tion and diffusion of each block. Although it has many
advantages, such as a large key space and high key
sensitivity, and so on, unfortunately, we find that this
method is vulnerable to the chosen plaintext attack.
The outline of this paper is as follows. In next
section, we describe the cryptosystem under study. In
Section 3 we demonstrate a chosen plaintext attack
that reveals the equivalent keys. In Section 4, we il-
lustrate the success in our break with experimental
results. Some security weaknesses and mistakes of the
scheme under study are given in Section 5. Finally,
we conclude the paper.
2. Wang and Teng’s cryptosys-
tem
In Wang and Teng’s cryptosystem, a CML is
adopted, which can be described as
x
n+1
(i) = (1 −ε)(f(x
n
(i)))
+
ε
2
(f(x
n
(i − 1)) + f(x
n
(i + 1))), (1)
where n is the time index, i (i = 1, 2, . . . , L) is the
lattice site index, ε ∈ (0, 1) is a coupling constant,
x
n
(i) represents the state variable for the i-th site at
∗
Project supported by the National Natural Science Foundation of China (Grant Nos. 61173183, 60973152, and 60573172), the
Doctoral Program Foundation of Institution of Higher Education of China (Grant No. 20070141014), and the Natural Science
Foundation of Liaoning Province, China (Grant No. 20082165).
†
Corresponding author. E-mail: wangxy@dlut.edu.cn
‡
Corresponding author. E-mail: hegxabc@126.com
c
2012 Chinese Physical Society and IOP Publishing Ltd
http://iopscience.iop.org/cpb
http://cpb.iphy.ac.cn
060502-1
资源评论
颜洛2015-07-09是英文的，看不懂，不过还是很感谢啦~
