Blind signature schemes (BSS) play a pivotal role in privacy‐oriented cryptography. However, with BSS, the signed message remains unintelligible to the signer, giving them no guarantee that the blinded message he signed actually contained valid information. Partially BSS (PBSS) were introduced to address precisely this problem. In this study, the authors present the first leakage‐resilient, lattice‐based PBSS in the literature. The proposed construction is provably secure in the random oracle model and offers quasi‐linear complexity w.r.t. key/signature sizes and signing speed. In addition, it offers statistical partial blindness and its unforgeability is based on the computational hardness of worst‐case ideal lattice problems for approximation factors in in dimension n . The proposed scheme benefits from the subexponential hardness of ideal lattice problems and remains secure even if a fraction of the signer's secret key leaks to an adversary via arbitrary side‐channels. Several extensions of the security model, such as honest‐user unforgeability and selective failure blindness, are also considered and concrete parameters for instantiation are proposed.

As online transactions become increasingly practical, a broad range of industrial and e-government applications have emerged which depend on time-based protection of confidential data. Despite theoretical progress in timed-release cryptography (TRC), there is still no implementation infrastructure that takes advantage of the latest TRC algorithms. The purpose of this paper is to propose such an infrastructure for pairing-based timed-release cryptography (PB-TRC) systems. Our model uses key generation centers (KGCs) which publish decryption keys periodically, and satisfies the security requirements of modern third party-based TRC schemes. Our approach combines the best features of existing models into a generic and complete infrastructure which is to support TRC. It is also "lighter" in terms of complexity and communication, and is as effective (in terms of security and related properties) as the TRC protocol it is used with.

The importance of software security has been profound, since most attacks to software systems are based on vulnerabilities caused by poorly designed and developed software. Furthermore, the enforcement of security in software systems at the design phase can reduce the high cost and effort associated with the introduction of security during implementation. For this purpose, security patterns that offer security at the architectural level have been proposed in analogy to the well-known design patterns. The main goal of this paper is to perform risk analysis of software systems based on the security patterns that they contain. The first step is to determine to what extent specific security patterns shield from known attacks. This information is fed to a mathematical model based on the fuzzy-set theory and fuzzy fault trees in order to compute the risk for each category of attacks. The whole process has been automated using a methodology that extracts the risk of a software system by reading the class diagram of the system under study.

We propose a new server-based efficient protocol for time-release encryption (TRE), or - as sometimes referred to - sending information "into the future". As with other recently-proposed schemes, ours is based on the use of bilinear pairings on any Gap Diffie-Hellman group, allowing absolute release time of the encrypted data. Our protocol possesses the required properties regarding user anonymity and server passivity. It also provides almost-costless scalability in settings with multiple time-servers, and improves significantly upon existing TRE schemes, in terms of computational and communication cost. This makes our approach well-suited to a number of emerging e-applications that require future decryption of confidential data.

This paper presents how a new teaching method in the way that a queuing theory and systems modeling or simulation course can be done, was evaluated by the teachers and the students that attended the course and answered a questionnaire. This course is based on the use of Unified Modeling Language (UML) as the mean to teach modeling of discrete event systems such as queues and networks and not on Mathematics that sometimes is too difficult for students to understand

The identification of design patterns as part of the reengineering process can convey important information to the designer. However, existing pattern detection methodologies generally have problems in dealing with one or more of the following issues: identification of modified pattern versions, search space explosion for large systems and extensibility to novel patterns. In this paper, a design pattern detection methodology is proposed that is based on similarity scoring between graph vertices. Due to the nature of the underlying graph algorithm, this approach has the ability to also recognize patterns that are modified from their standard representation. Moreover, the approach exploits the fact that patterns reside in one or more inheritance hierarchies, reducing the size of the graphs to which the algorithm is applied. Finally, the algorithm does not rely on any pattern-specific heuristic, facilitating the extension to novel design structures. Evaluation on three open-source projects demonstrated the accuracy and the efficiency of the proposed method

Of all merits of the object-oriented paradigm, flexibility is probably the most important in a world of constantly changing requirements and the most striking difference compared to previous approaches. However, it is rather difficult to quantify this aspect of quality: this paper describes a probabilistic approach to estimate the change proneness of an object-oriented design by evaluating the probability that each class of the system will be affected when new functionality is added or when existing functionality is modified. It is obvious that when a system exhibits a large sensitivity to changes, the corresponding design quality is questionable. The extracted probabilities of change can be used to assist maintenance and to observe the evolution of stability through successive generations and identify a possible "saturation" level beyond which any attempt to improve the design without major refactoring is impossible. The proposed model has been evaluated on two multiversion open source projects. The process has been fully automated by a Java program, while statistical analysis has proved improved correlation between the extracted probabilities and actual changes in each of the classes in comparison to a prediction model that relies simply on past data.

In this paper we suggest a new approach in the way that a network modeling and simulation or a queuing theory course can be developed. Beyond the mathematical model that sometimes is too difficult for students to understand, this paper introduces the use of Unified Modeling Language as the mean to teach modeling of discrete event systems such as queues and networks. The basic course scheduling and teaching material are presented too.

The hyperlink induced topic search algorithm, which is a method of link analysis, primarily developed for retrieving information from the Web, is extended in this paper, in order to evaluate one aspect of quality in an object-oriented model. Considering the number of discrete messages exchanged between classes, it is possible to identify "God" classes in the system, elements which imply a poorly designed model. The principal eigenvectors of matrices derived from the adjacency matrix of a modified class diagram, are used to identify and quantify heavily loaded portions of an object-oriented design that deviate from the principle of distributed responsibilities. The non-principal eigenvectors are also employed in order to identify possible reusable components in the system. The methodology can be easily automated as illustrated by a Java program that has been developed for this purpose.

We introduce a software application that simulates the most common types of queues. It also compares the simulation results with the values that the mathematical model predicts for specific types of queues. Thus, the software we have developed has two academic aspects. The first one applies to its ability to simulate most of the queuing processes that take place in computer networks. Therefore someone who studies network modelling or computer performance analysis may use it to derive some practical results in a very convenient way. The second aspect of the software refers to the part of the application that simulates specific types of queue and it can be used as a guide for teaching network modelling. We believe that it is very easy for someone to understand the aspects of queuing theory even though he/she is not familiar with it.