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匹配条件: “Yaser Sadra” ,找到相关结果约216条。
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A Pseudorandom Bit Generator based on Chaotic Coupled Map Lattices
Sodeif Ahadpour,Yaser Sadra
Journal of Theoretical Physics and Cryptography , 2012,
Abstract: In this paper, we discuss the properties of making a deterministic algorithm suitable to generate a pseudo random sequence of numbers: high value of Kolmogorov-Sinai entropy, high dimensionality of the parent dynamical system, and very large period of the generated sequence. We propose the chaotic coupled map lattices as a pseudo random number generator. We show what chaotic features of the coupled map lattices are useful for generating pseudo random numbers and investigate numerically which of them survive in the discrete state version of the map. To evaluate the randomness of the bit sequences generated by the RNGs, the NIST suite tests were performed. The proposed RNGs can be used in many applications requiring random bit sequences and also in the design of secure cryptosystems.
A Chaos-based Image Encryption Scheme using Chaotic Coupled Map Lattices
Sodeif Ahadpour,Yaser Sadra
Computer Science , 2012, DOI: 10.5120/7599-0311
Abstract: In recent years, information security essential in various arenas like internet communication, multimedia systems, medical imaging, tele-medicine and military communication. However, most of them faced with some problems such as the lack of robustness and security. In this letter, after reviewing the main points of the chaotic trigonometric maps and the coupled map lattices, we introduce the scheme of chaos-based image encryption based on coupled map lat tices. The scheme decreases periodic effect of the ergodic dynamical systems in the chaos-based image encryption. To evaluate the security of the encrypted image of this scheme, the key space analysis, the correlation of two adjacent pixels and differential attack were performed. This scheme tries to improve the problem of failure of encryption such as small key space and level of security.
Chaotic trigonometric haar wavelet with focus on image encryption
Sodeif Ahadpour,Yaser Sadra
Computer Science , 2014,
Abstract: In this paper, after reviewing the main points of Haar wavelet transform and chaotic trigonometric maps, we introduce a new perspective of Haar wavelet transform. The essential idea of the paper is given linearity properties of the scaling function of the Haar wavelet. With regard to applications of Haar wavelet transform in image processing, we introduce chaotic trigonometric Haar wavelet transform to encrypt the plain images. In addition, the encrypted images based on a proposed algorithm were made. To evaluate the security of the encrypted images, the key space analysis, the correlation coefficient analysis and differential attack were performed. Here, the chaotic trigonometric Haar wavelet transform tries to improve the problem of failure of encryption such as small key space and level of security.
A novel chaotic encryption scheme based on pseudorandom bit padding
Sodeif Ahadpour,Yaser Sadra,Zahra Arasteh Fard
International Journal of Computer Science Issues , 2012,
Abstract: Cryptography is always very important in data origin authentications, entity authentication, data integrity and confidentiality. In recent years, a variety of chaotic cryptographic schemes have been proposed. These schemes has typical structure which performed the permutation and the diffusion stages, alternatively. The random number generators are intransitive in cryptographic schemes and be used in the diffusion functions of the image encryption for diffused pixels of plain image. In this paper, we propose a chaotic encryption scheme based on pseudorandom bit padding that the bits be generated by a novel logistic pseudorandom image algorithm. To evaluate the security of the cipher image of this scheme, the key space analysis, the correlation of two adjacent pixels and differential attack were performed. This scheme tries to improve the problem of failure of encryption such as small key space and level of security.
Synthesis and conformational analysis of new derivatives of 7-chloro-1,3-dihydro-5-phenyl-2h-1,4-benzodiazepine-2-one
Gholamhassan Imanzadeh,Zahra ArastehFard,Yaser Sadra
Physics , 2011,
Abstract: 1,4-benzodiazepine-2-ones and their derivatives are prominent structures in medicinal chemistry. These biomolecules have wide biological activities and posses therapeutic applications. In this works, we introduce new derivatives of 1,4-benzodiazepine-2-ones which are synthesized using michael addition reaction of 7-chloro- 1,3-dihydro-5-phenyl-2H-1,4-benzodiazepine-2-ones with fumaric esters that matches with green chemistry protocols. The structures of all products are confirmed by FT-IR, 1H-NMR, 13C-NMR and MASS spectroscopy. Since the stereochemistry of 1,4-benzo diazepine-2-ones is important, we study the most stable conformer of one of the products as a model for conformational analysis by hyper chem soft ware and semi empirical AM1 program. Also, using the 1H-NMR spectrum, we investigate the produced diastereomers of one of products as a model.
A Novel Chaotic Image Encryption using Generalized Threshold Function
Sodeif Ahadpour,Yaser Sadra,Zahra ArastehFard
Computer Science , 2011, DOI: 10.5120/5794-8110
Abstract: In this paper, after reviewing the main points of image encryption and threshold function, we introduce the methods of chaotic image encryption based on pseudorandom bit padding that the bits be generated by the novel generalized threshold function (segmentation and self-similarity) methods. These methods decrease periodic effect of the ergodic dynamical systems in randomness of the chaotic image encryption. The essential idea of this paper is that given threshold functions of the ergodic dynamical systems. To evaluate the security of the cipher image of this scheme, the key space analysis, the correlation of two adjacent pixels and differential attack were performed. This scheme tries to improve the problem of failure of encryption such as small key space and level of security.
A Novel Chaotic Encryption Scheme based on Pseudorandom Bit Padding
Sodeif Ahadpour,Yaser Sadra,Zahra ArastehFard
Computer Science , 2012,
Abstract: Cryptography is always very important in data origin authentications, entity authentication, data integrity and confidentiality. In recent years, a variety of chaotic cryptographic schemes have been proposed. These schemes have typical structure which performed the permutation and the diffusion stages, alternatively. The random number generators are intransitive in cryptographic schemes and be used in the diffusion functions of the image encryption for diffused pixels of plain image. In this paper, we propose a chaotic encryption scheme based on pseudorandom bit padding that the bits be generated by a novel logistic pseudorandom image algorithm. To evaluate the security of the cipher image of this scheme, the key space analysis, the correlation of two adjacent pixels and differential attack were performed. This scheme tries to improve the problem of failure of encryption such as small key space and level of security.
Public key Steganography Using Discrete Cross-Coupled Chaotic Maps
Sodeif Ahadpour,Mahdiyeh Majidpour,Yaser Sadra
Computer Science , 2012,
Abstract: By cross-coupling two logistic maps a novel method is proposed for the public key steganography in JPEG image. Chaotic maps entail high complexity in the used algorithm for embedding secret data in a medium. In this paper, discrete cross- coupled chaotic maps are used to specifying the location of the different parts of the secret data in the image. Modifying JPEG format during compressing and decompressing, and also using public key enhanced difficulty of the algorithm. Simulation results show that in addition to excessive capacity, this method has high robustness and resistance against hackers and can be applicable in secret communication. Also the PSNR value is high compared to the other works.
Markov-Binary Visibility Graph: a new method for analyzing Complex Systems
Yaser Sadra,Zahra Arasteh-Fard,Sodief Ahadpour
Physics , 2011,
Abstract: In this work, we introduce a new and simple transformation from time series to complex networks based on markov-binary visibility graph(MBVG). Due to the simple structure of this transformation in comparison with other transformations be obtained more precise results. Moreover, several topological aspects of the constructed graph, such as degree distribution, clustering coefficient, and mean visibility length have been thoroughly investigated. Numerical simulations confirm the reliability of markov-binary visibility graph for time series analysis. This algorithm have the capability of distinguishing between uncorrelated and correlated systems. Finaly, we illustrate this algorithm analyzing the human heartbeat dynamics. The results indicate that the human heartbeat (RR-interval) time series of normally, Congestive Heart Failure (CHF) and Atrial Fibrillation (AF) subjects are uncorrelated, chaotic and correlated stochastic systems, respectively.
The Plurality of the Sacred—Critical Remarks on Mircea Eliade’s Conception of the Sacred  [PDF]
Yaser Mirdamadi
Open Journal of Philosophy (OJPP) , 2015, DOI: 10.4236/ojpp.2015.57048
Abstract: Mircea Eliade’s conception of the sacred, confining it to religious sacred, is criticized. A more comprehensive model of the sacred, which includes non-religious sacred, is developed and human love is suggested as a good candidate for non-religious sacred.
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