Security Analysis and Enhancement of One-Way Hash Based Low-Cost Authentication Protocol (OHLCAP)

Choi et al. recently proposed an efficient RFID authentication protocol for a ubiquitous computing environment, OHLCAP(One-Way Hash based Low-Cost Authentication Protocol). However, this paper reveals that the protocol has several security weaknesses : 1) traceability based on the leakage of counter information, 2) vulnerability to an impersonation attack by maliciously updating a random number, and 3) traceability based on a physically-attacked tag. Finally, a security enhanced group-based authentication protocol is presented

Design Strategies and Modified Descriptions to Optimize Cipher FPGA Implementations: Fast and Compact Results for DES and Triple-DES

Abstract. In this paper, we propose a new mathematical DES description that allows us to achieve optimized implementations in term of ratio T hroughput/Area. First, we get an unrolled DES implementation that works at data rates of 21.3 Gbps (333 MHz), using Virtex-II technology. In this design, the plaintext, the key and the mode (encryption/decrytion) can be changed on a cycle-by-cycle basis with no dead cycles. In addition, we also propose sequential DES and triple-DES designs that are currently the most efficient ones in term of resources used as well as in term of throughput. Based on our DES and triple-DES results, we also set up conclusions for optimized FPGA design choices and possible improvement of cipher implementations with a modified structure description

Parâmetros genéticos da taxa de maturação e do peso assintótico de fêmeas da raça Nelore Genetic parameters of maturation rate and asymptotic weight of Nelore females

Utilizaram-se 14.563 pesagens de 1158 fêmeas da raça Nelore, nascidas entre 1984 e 1995, pertencentes a 10 fazendas, distribuídas em sete estados do Brasil. Com o objetivo de estabelecer um padrão médio de crescimento, obter parâmetros individuais das curvas e estimar os componentes de variância, herdabilidade e correlações genéticas dos parâmetros das curvas, foram comparados os modelos de Von Bertalanffy, Brody, logístico e Gompertz. Foram utilizados o procedimento NLIN e o programa MTDFREML sob modelo animal em análise unicaráter e bicaráter. Os parâmetros médios dos pesos assintóticos (A) e das taxas de maturidade (K) foram: 515,06 e 0,071 para Von Bertalanffy; 552,77 e 0,045 para Brody; 501,11 e 0,097 para logístico, e 507,00 e 0,083 para Gompertz, respectivamente. As estimativas de herdabilidade para A e K foram de alta magnitude: 0,39 e 0,42 para Von Bertalanffy, 0,42 e 0,44 para Brody, 0,40 e 0,41 para logístico e 0,39 e 0,39 para Gompertz, respectivamente. As correlações genéticas variaram entre -0,69 e -0,49. Todos os modelos foram adequados para descrever o crescimento. A ordem de escolha do melhor modelo para descrever a curva de crescimento foi: Brody, Von Bertalanffy, logístico e Gompertz. Essas características seriam passíveis de inclusão em índice de seleção para seleção de fêmeas Nelore.<br>Data from 1158 females Nellore beef cattle, born between 1984 and 1995, at 10 breeding farms and located at seven differents States of Brazil were used to establish a growth pattern curve of beef cattle females, and to estimate variance components, heritabilities and genetic correlations between the parameters for Von Bertalanffy, Brody, logístic and Gompertz models. The NLIN procedure and the MTDFREML program under animal model were used for single and two trait analyses. The average weight (A) and growth rate (K) were 515.06 and .071 for Von Bertalanffy; 552.77 and .045 for Brody; 501.11 and .097 for logistic; and 507.00 and .083 for Gompertz, respectively. High heritabilities were estimated for A and K parameters: .39 and .42 for Von Bertalanffy; .42 and .44 for Brody; .40 and .41 for logistic; and .39 and .39 for Gompertz, respectively. All the models described adequately the growth pattern of those females. The best model to describe the growth curve based on the number of iteractions for convergence, error mean square and the coefficient of determination was Brody model, followed by Von Bertalanffy, logistic and Gompetz models. These characteristics (A and K parameters) could be included in selection index for female Nelore selection