Chaotic S-box Construction And Its Application In Image Encryption

With the rapid development of computer technology and network technology,the problem of information security has attracted wide attention and attention.In order to improve the information security,cryptography has become a hot research hotspot.S-box is the core module of the block cipher system,which can obtain high reliability password by improving the design level of S-box.In traditional cryptography,S-box is constructed by algebraic method,although it can obtain very high non-linearity,but because the structure is too simple,the difference performance is relatively weak,unable to resist algebraic attack.The chaotic system can be used to design more ideal S-box due to its advantages of ergodic,mixed,initial conditions and parameters.Therefore,S-box based on chaotic system research to the attention of the procession of the researchers in the field of information security,using the excellent characteristics of chaos system to construct new S-box of rapid development become a hot research direction in the field of information security.This paper mainly focuses on the construction of chaotic S-box and its application in image encryption.Using the excellent properties of chaotic system,the fixed chaotic S-box,dynamic chaotic S-box and chaotic S-box algorithm constructed by optimization method are constructed,which are used in image encryption respectively.The main research contents of this paper are as follows:?1?A method of constructing S-box using six dimensional fractional-order Lorenz-duffing chaotic system and O-shaped path scrambling is designed and implemented in this thesis.To solve this drawback,this thesis first proposes a novel six-dimensional fractional-order Lorenz-duffing chaotic system based on the analysis and research of the existing six-dimensional Lorenz-duffing system.A frequency domain approximation approach is exploited to perform the numerical simulation and circuit simulation for the novel method.Experimental results of the circuit simulation and numerical simulation are consistent,which verifies the validity and feasibility of the proposed fractional-order chaotic system.Then,the S-box is constructed by using the proposed fractional-order chaotic system and O-shaped path scrambling.Researchers are now paying attention to the image encryption based on chaotic S-boxes.In this thesis,an image encryption method based on the S-box and nonlinear chaotic map is also proposed.It first designs an additional 256-bit key to extend the key space of the method.Next,it correlates the key with the plaintext to enhance the capability of resisting chosen and known plaintexts attacks for the method.In addition,it exploits a Logistic-Tent?L-T?cascade map to scramble the input image and splits the scrambled image into several blocks.Furthermore,it utilizes a chaotic S-box generated by a fractional-order Lorenz-duffing chaotic system to scramble each block.Finally,it leverages a non-linear chaotic map to diffuse each block to obtain an encrypted image.Experimental results show that the algorithm achieves good encryption results.?2?Furthermore,an image encryption algorithm based on chaotic dynamic S-boxes and DNA sequence operation is designed and implemented in this thesis.First,this method designs an additional 256-bit key to produce the initial values and control parameters of the chaotic systems.Second,it adopts an existing new chaotic?NC?map to scramble the input image and split the scrambled image into several blocks.Third,it generates a dynamic S-box using the Cubic-Tent?C-T?cascade map and reversible two-dimensional map of structure-triangle to encrypt each image block and encodes the block with the DNA coding strategy.Fourth,it uses the C-T cascade map to yield a data matrix that has the same size as an image block and uses the improved generalized two-dimensional Arnold transform to scramble the data matrix.Fifth,it utilizes the C-T cascade map to generate five random sequences and adopts the DNA coding rules selected by the first three sequences to perform DNA decoding on the DNA encoded image block,data matrix,and the scrambled data matrix respectively.Sixth,the DNA coding rules selected by the remaining two random sequences are exploited to execute DNA operation on the DNA encoded image block,data matrix,and the scrambled data matrix.Seventh,it performs the DNA decoding operation on the encrypted block and assembles image blocks into the cipher image according to the corresponding positions of the plaintext image blocks.Experimental results show that the algorithm has more flexible ability to analyze and attack cryptographic techniques.?3?A new method of S-box design is proposed using optimization method.Firstly,the artificial bee colony algorithm is combined with the six dimensional Lorenz-duffing chaotic system to construct the S-box,in which the nonlinearity and differential uniformity of the S-box evaluation index are used as fitness functions,and the S-boxes with excellent cryptographic performance can be obtained,then,the S-box is used for image encryption.It designs an additional and plaintext-correlated 256-bit key and then uses a Logistic-Logistic?L-L?cascade map to scramble the input image and splits the scrambled image into eight bit-planes.Next,it utilizes an improved two-dimensional Arnold transformation to scramble four high-bit-planes.The results are then combined with four low-bit-planes to form an image.This method also transforms the chaotic S-box generated by the artificial bee colony algorithm into S₈ S-boxes.Moreover,both S₈ S-boxes and a random sequence created by a wrapped Logistic map are involved to diffusing the image.Experimental results show that the algorithm has the ability to resist common attacks.