8 results on '"Pareek, N.K."'
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2. A robust and secure chaotic standard map based pseudorandom permutation-substitution scheme for image encryption
- Author
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Patidar, Vinod, Pareek, N.K., Purohit, G., and Sud, K.K.
- Subjects
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IMAGE processing , *ROBUST control , *CHAOS theory , *DATA encryption , *CRYPTOGRAPHY , *ALGORITHMS , *ITERATIVE methods (Mathematics) , *SENSITIVITY analysis , *ENTROPY (Information theory) - Abstract
Abstract: A novel and robust chaos-based pseudorandom permutation–substitution scheme for image encryption is proposed. It is a loss-less symmetric block cipher and specifically designed for the color images but may also be used for the gray scale images. A secret key of 161-bit, comprising of the initial conditions and system parameter of the chaotic map (the standard map), number of iterations and number of rounds, is used in the algorithm. The whole encryption process is the sequential execution of a preliminary permutation and a fix number of rounds (as specified in the secret key) of substitution and main permutation of the 2D matrix obtained from the 3D image matrix. To increase the speed of encryption all three processes: preliminary permutation, substitution and main permutation are done row-by-row and column-by-column instead of pixel-by-pixel. All the permutation processes are made dependent on the input image matrix and controlled through the pseudo random number sequences (PRNS) generated from the discretization of chaotic standard map which result in both key sensitivity and plaintext sensitivity. However each substitution process is initiated with the initial vectors (different for rows and columns) generated using the secret key and chaotic standard map and then the properties of rows and column pixels of input matrix are mixed with the PRNS generated from the standard map. The security and performance analysis of the proposed image encryption has been performed using the histograms, correlation coefficients, information entropy, key sensitivity analysis, differential analysis, key space analysis, encryption/decryption rate analysis etc. Results suggest that the proposed image encryption technique is robust and secure and can be used for the secure image and video communication applications. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
3. Image encryption using chaotic logistic map
- Author
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Pareek, N.K., Patidar, Vinod, and Sud, K.K.
- Subjects
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CRYPTOGRAPHY , *ALGORITHMS , *DATA encryption , *IMAGE compression - Abstract
Abstract: In recent years, the chaos based cryptographic algorithms have suggested some new and efficient ways to develop secure image encryption techniques. In this communication, we propose a new approach for image encryption based on chaotic logistic maps in order to meet the requirements of the secure image transfer. In the proposed image encryption scheme, an external secret key of 80-bit and two chaotic logistic maps are employed. The initial conditions for the both logistic maps are derived using the external secret key by providing different weightage to all its bits. Further, in the proposed encryption process, eight different types of operations are used to encrypt the pixels of an image and which one of them will be used for a particular pixel is decided by the outcome of the logistic map. To make the cipher more robust against any attack, the secret key is modified after encrypting each block of sixteen pixels of the image. The results of several experimental, statistical analysis and key sensitivity tests show that the proposed image encryption scheme provides an efficient and secure way for real-time image encryption and transmission. [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
4. Discrete chaotic cryptography using external key
- Author
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Pareek, N.K., Patidar, Vinod, and Sud, K.K.
- Subjects
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CRYPTOGRAPHY , *CIPHERS - Abstract
In this Letter, we propose a symmetric key block cipher algorithm utilizing the essence of chaos. The proposed cryptosystem does not use explicitly the system parameter or initial condition of the chaotic map as a secret key. However, these parameters are generated by an external secret key of variable length (maximum 128-bits) and used in our algorithm. The encryption of each block of plaintext has been made dependent on the secret key and the cryptosystem is further made robust against any reasonable attack by using the feedback technique. Simulation results show that the proposed cryptosystem requires less time to encrypt the plaintext as compared to the existing chaotic cryptosystems and further produces the ciphertext having flat distribution of same size as the plaintext. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
5. Suppression of chaos using mutual coupling
- Author
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Patidar, Vinod, Pareek, N.K., and Sud, K.K.
- Subjects
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HARMONIC oscillators , *CHAOS theory , *BIFURCATION theory - Abstract
We demonstrate in this communication the suppression of chaos in a chaotic oscillator by establishing mutual coupling with an another weak periodic oscillator of the same kind. We have chosen specific locations of the state variable for the mutual coupling and the suppression of chaos is observed via period halving route as a result of increase in mutual coupling strength between the oscillators. The technique developed does not require any prior knowledge of the system dynamics and the system parameters are not changed explicitly. The method is expected to be useful for those physical chaotic systems in which direct accessibility of its parameters is either difficult or not possible. [Copyright &y& Elsevier]
- Published
- 2002
- Full Text
- View/download PDF
6. Modified substitution–diffusion image cipher using chaotic standard and logistic maps
- Author
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Patidar, Vinod, Pareek, N.K., Purohit, G., and Sud, K.K.
- Subjects
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CHAOS theory , *CRYPTOGRAPHY , *DIFFUSION , *POLYNOMIALS , *BIFURCATION theory , *CARTOGRAPHY , *NONLINEAR theories - Abstract
Abstract: Recently Patidar et al. [Commun Nonlinear Sci Numer Simulat 14;2009:3056–75] proposed a new substitution–diffusion image cipher using chaotic standard and logistic maps, which is very fast and possess all the confusion and diffusion properties that any good cryptosystem should have. Soon after the proposal, Rhouma et al. [Commun Nonlinear Sci Numer Simulat 2010;15:1887–92.] proposed an equivalent description of the PPS09 cryptosystem which facilitated them in the cryptanalysis of the original cipher in terms of chosen plainext and known plaintext attacks. In this paper, we propose modifications in the Patidar et al.’s image cipher to make it robust against these two cryptanalytic attacks. The security analysis shows that the modified image cipher preserves all the good properties of the original cipher and is also capable to stand against the aforesaid attacks. [Copyright &y& Elsevier]
- Published
- 2010
- Full Text
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7. A new substitution–diffusion based image cipher using chaotic standard and logistic maps
- Author
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Patidar, Vinod, Pareek, N.K., and Sud, K.K.
- Subjects
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CIPHERS , *DATA encryption , *CHAOS theory , *NONLINEAR theories , *ITERATIVE methods (Mathematics) - Abstract
Abstract: In this paper, we propose a new loss-less symmetric image cipher based on the widely used substitution–diffusion architecture which utilizes chaotic standard and logistic maps. It is specifically designed for the coloured images, which are 3D arrays of data streams. The initial condition, system parameter of the chaotic standard map and number of iterations together constitute the secret key of the algorithm. The first round of substitution/confusion is achieved with the help of intermediate XORing keys calculated from the secret key. Then two rounds of diffusion namely the horizontal and vertical diffusions are completed by mixing the properties of horizontally and vertically adjacent pixels, respectively. In the fourth round, a robust substitution/confusion is accomplished by generating an intermediate chaotic key stream (CKS) image in a novel manner with the help of chaotic standard and logistic maps. The security and performance of the proposed image encryption technique has been analyzed thoroughly using various statistical analysis, key sensitivity analysis, differential analysis, key space analysis, speed analysis, etc. Results of the various types of analysis are encouraging and suggest that the proposed image encryption technique is able to manage the trade offs between the security and speed and hence suitable for the real-time secure image and video communication applications. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
8. Cryptography using multiple one-dimensional chaotic maps
- Author
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Pareek, N.K., Patidar, Vinod, and Sud, K.K.
- Subjects
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CRYPTOGRAPHY , *ALGORITHMS , *SIMULATION methods & models , *CIPHERS , *DATA encryption - Abstract
Recently, Pareek et al. [Phys. Lett. A 309 (2003) 75] have developed a symmetric key block cipher algorithm using a one-dimensional chaotic map. In this paper, we propose a symmetric key block cipher algorithm in which multiple one-dimensional chaotic maps are used instead of a one-dimensional chaotic map. However, we also use an external secret key of variable length (maximum 128-bits) as used by Pareek et al. In the present cryptosystem, plaintext is divided into groups of variable length (i.e. number of blocks in each group is different) and these are encrypted sequentially by using randomly chosen chaotic map from a set of chaotic maps. For block-by-block encryption of variable length group, number of iterations and initial condition for the chaotic maps depend on the randomly chosen session key and encryption of previous block of plaintext, respectively. The whole process of encryption/decryption is governed by two dynamic tables, which are updated time to time during the encryption/decryption process. Simulation results show that the proposed cryptosystem requires less time to encrypt the plaintext as compared to the existing chaotic cryptosystems and further produces the ciphertext having flat distribution of same size as the plaintext. [Copyright &y& Elsevier]
- Published
- 2005
- Full Text
- View/download PDF
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