Sharif Digital Repository

Diffusion of key schedule algorithm plays an important role in security of block ciphers. In this paper, we present a new approach to key schedule diffusion analysis by taking the advantages of graph theory modeling. This modeling can help to disclose the weaknesses of key schedules. In this line, the key schedule weaknesses of Twine-128 are shown and an improved key schedule is proposed. In order to make a fair comparison, some parameters are introduced to quantify the diffusion property of key schedule, and compare the results for Twine-128 with both key schedules. The results show that the new key schedule made Twine-128 stronger. Also for more reliability, the results of biclique attack... 

Security evaluation of lightweight block ciphers plays a critical role to determine security margin of these ciphers. One of the methods to find the security margin of block ciphers is biclique cryptanalysis. In this paper, we present a new schematic for biclique attack which combines asymmetric biclique and early abort technique. Then, we apply it against Twine-128 to evaluate the security margin of Twine-128. As a result, we present two cryptanalysis for Twine-128, one with 2125.75 computational complexity and 260 data complexity, and the other with 212616 computational complexity and 28 data complexity. To the best of our knowledge, our results are the best in computational and data... 

This paper deals with the optimum design of vibration absorbers utilized to reduce undesirable random vibrational effects that are originated in linear structures. Analytical expressions, for the case of nonstationary white-noise accelerations, are derived. The criterion is different from most conventional optimum design criteria, since it is based on minimizing the displacement or the acceleration variance of the main structure responses, without considering performances required against failure. In this study, in order to control the structural vibrations induced on a mechanical structure excited by nonstationary based acceleration random process, the MOO (multi-objective optimum) design... 

In a secure multiparty computation (MPC) system, there are some sources, where each one has access to a private input. The sources want to offload the computation of a polynomial function of the inputs to some processing nodes or workers. The processors are unreliable, i.e., a limited number of them may collude to gain information about the inputs. The objective is to minimize the number of required workers to calculate the polynomial, while the colluding workers gain no information about inputs. In this paper, we assume that the inputs are massive matrices, while the workers have the limited computation and storage at each worker. As proxy for that, we assume the link between each source... 

In this work1, we consider the problem of secure multi-party computation (MPC), consisting of F sources, each has access to a large private matrix, N processing nodes or workers, and one master. The master is interested in the result of a polynomial function of the input matrices. Each source sends a randomized functions of its matrix, called as its share, to each server. The workers process their shares in interaction with each other, and send some results to the master such that it can derive the final results. There are several constraints: (1) each worker has a constraint on its storage, such that it can store equivalent of displaystyle rac{1}{m} fraction of size of each input matrices... 

In this paper, we propose a hybrid algorithm including Genetic Algorithm (GA), Ant Colony Optimisation (ACO), and Simulated Annealing (SA) metaheuristics for increasing the contrast of images. In this way, contrast enhancement is obtained by global transformation of the input intensities. Ant colony optimisation is used to generate the transfer functions which map the input intensities to the output intensities. Simulated annealing as a local search method is utilised to modify the transfer functions generated by ant colony optimisation. And genetic algorithm has the responsibility of evolutionary process of antsE characteristics. The employed fitness function operates automatically and... 

In this paper, we propose a hybrid algorithm including Genetic Algorithm (GA), Ant Colony Optimization (ACO), and Simulated Annealing (SA) metaheuristics for increasing the contrast of images. In this way, the contrast enhancement is obtained by globally transformation of the input intensities. ACO is used to generate the transfer functions which map the input intensities to the output intensities. SA as a local search method is utilized to modify the transfer functions generated by ACO. GA has the responsibility of evolutionary process of ants' characteristics. The results indicate that the new method performs better than the previously presented methods from the subjective and objective... 

The objective of this paper is study of flowfield over the wing of a coplanar and close-coupled wing-canard configuration model using neural network, in order to reduce measurement points and experiment time. The results are based on flowfield pressure and wing surface pressure measurements at difference angles of attack, no sideslip and difference angles of canard. A GRNN (General Regression Neural Network) algorithm is developed to determine the shape and trajectory of vortices over this model. This network uses the total pressure coefficients of flowfield over the wing of this model that are obtained by total pressure probe as its input. The data presented to the network are processed to... 

Universal deployment of lightweight block ciphers increase the importance of cryptanalysis of these ciphers. In this paper, we focus on reduced round version of Piccolo-80 as a lightweight block cipher and try to analyze it by zero correlation linear attack. As a result, we proposed a new zero correlation linear attack on 12-round Piccolo-80 without whitening keys with computational complexity of 251.4, while memory and data complexities of the attack are equal to 258.2 and 250, respectively. Also, we proposed an attack on 12-round Piccolo-80 with whitening keys and 13-round Piccolo-80 without whitening keys. To the best of our knowledge, these are the first zero correlation attacks on...