Pub. online:5 Aug 2022Type:Research ArticleOpen Access
Journal:Informatica
Volume 16, Issue 1 (2005), pp. 37–44
Abstract
In 1995, Wu proposed a remote login authentication scheme based on geometric approach. However, Chien, Jan and Tseng presented a cryptanalysis of Wu’s scheme to show that it is not secure. Moreover, they proposed a modified version of Wu’s scheme. This paper presents there is a serious weakness in this modified remote login authentication scheme. We show that an illegal user can easily forge a valid login request in the modified version proposed previously.
Journal:Informatica
Volume 14, Issue 3 (2003), pp. 289–294
Abstract
Smart card has been adopted to various applications. In 2000, Hwang and Li proposed a remote user authentication scheme, which is also using smart card. Nine months later, Chan and Cheng pointed out that there is a weakness in the remote authentication scheme proposed by Hwang and Li. In this paper, we show that Chan and Cheng's attack does not work well because they did not consider the format of user's identity. In addition, we propose several ways to solve the problem of Chan and Cheng's attack.
Journal:Informatica
Volume 14, Issue 2 (2003), pp. 155–166
Abstract
A partially blind signature scheme allows the signer to inoculate a non‐removable common information into his blind signature. This common information may represent the date or the amount of e‐cash. Due to its un‐traceablility and partial blindness property, the partially blind signature plays an important role in many e‐commerce applications. Based on the RSA scheme, we propose a partially blind threshold signature with low‐computational load for the client.
Journal:Informatica
Volume 12, Issue 1 (2001), pp. 45–60
Abstract
The analysis of the method for multiple criteria optimization problems applying a computer network has been presented in the paper. The essence of the proposed method is the distribution of the concrete optimization problem into the network rather than the parallelization of some optimization method. The aim of the authors is to design and investigate the interactive strategies to solve complex multiple criteria problems by applying a computer network. The optimized objective function is the weight sum of the criteria. The multiple criteria problem is iterated by selecting interactively different weight coefficients of the criteria. Therefore, the process is organized by designating the computers as the master (that coordinates the process of other computers) and the slaves (that execute different tasks). In the beginning of the process the researcher allocates a certain number of optimization problems to the network. The objective function optimization problems differ only in weight coefficients of the criteria. As soon as the task of a slave has been executed, the result is sent to the master. Every computer of the network behaves in analogous way. Whenever the researcher receives an immediate result from one of the computers, he gives a decision taking into consideration the latter and all the previous results, i.e., he selects new weight coefficients for the criteria and assigns a new task to the network. Likewise the multiple criteria problem is solved until the result is acceptable for the researcher. The application of the proposed method is illustrated on the basis of the problem for the selection of the optimal nutritive value. Message Passing Interface (MPI) software has been used. The trials have been carried out with the network of computers under the operation system Windows NT.
Journal:Informatica
Volume 11, Issue 1 (2000), pp. 15–18
Abstract
Recently, Harn proposed an efficient scheme that can batch verification multiple RSA digital signatures. His scheme can reduce signature verification time. However, there is a weakness in his scheme. In this study, we present two methods to against his scheme.