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1

Two semantics of trust management language with negation

Felkner A.

Journal of Telecommunications and Information Technology

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2013

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nr 4

102--108

EN

The family of Role-based Trust management languages is used for representing security policies by defining a formalism, which uses credentials to handle trust in decentralized, distributed access control systems. A credential provides information about the privileges of users and the security policies issued by one or more trusted authorities. The main topic of this paper is RT⊖, a language which provides a carefully controlled form of non-monotonicity. The core part of the paper defines two different semantics of RT⊖ language – a relational, set-theoretic semantics for the language, and an inference system, which is a kind of operational semantics. The set-theoretic semantics maps roles to a set of entity names. In the operational semantics credentials can be derived from an initial set of credentials using a set of inference rules. The soundness and the completeness of the inference system with respect to the set-theoretic semantics of RT⊖ will be proven.

2

RTT+ - Time Validity Constraints in RTT Language

Felkner A., Kozakiewicz A.

Journal of Telecommunications and Information Technology

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2012

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nr 2

74-82

EN

Most of the traditional access control models, like mandatory, discretionary and role based access control make authorization decisions based on the identity, or the role of the requester, who must be known to the resource owner. Thus, they may be suitable for centralized systems but not for decentralized environments, where the requester and service provider or resource owner are often unknown to each other. To overcome the shortcomings of traditional access control models, trust management models have been presented. The topic of this paper is three different semantics (set-theoretic, operational, and logic- programming) of RTT , language from the family of role-based trust management languages (RT). RT is used for representing security policies and credentials in decentralized, distributed access control systems. A credential provides information about the privileges of users and the security policies issued by one or more trusted authorities. The set-theoretic semantics maps roles to a set of sets of entity names. Members of such a set must cooperate in order to satisfy the role. In the case of logic-programming semantics, the credentials are translated into a logic program. In the operational semantics the credentials can be established using a simple set of inference rules. It turns out to be fundamental mainly in large- scale distributed systems, where users have only partial view of their execution context. The core part of this paper is the introduction of time validity constraints to show how that can make RTT language more realistic. The new language, named RTT+ takes time validity constraints into account. The semantics for RTT+ language will also be shown. Inference system will be introduced not just for specific moment but also for time intervals. It will evaluate maximal time validity, when it is possible to derive the credential from the set of available credentials. The soundness and completeness of the inference systems with the time validity constraints with respect to the set-theoretic semantics of RTT+ will be proven.

3

How the Role-Based Trust Management Can Be Applied to Wireless Sensor Networks

Felkner A.

Journal of Telecommunications and Information Technology

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2012

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nr 4

70-77

EN

Trust plays an important role in human life environments. That is why the researchers has been focusing on it for a long time. It allows us to delegate tasks and decisions to an appropriate person. In social sciences trust between humans was studied, but it also was analyzed in economic transactions. A lot of computer scientists from different areas, like security, semantic web, electronic commerce, social networks tried to transfer this concept to their domains. Trust is an essential factor in any kind of network, whether social or computer. Wireless sensor networks (WSN) are characterized by severely constrained resources, they have limited power supplies, low transmission bandwidth, small memory sizes and limited energy, therefore security techniques used in traditional wired networks cannot be adopted directly. Some effort has been expended in this fields, but the concept of trust is defined in slightly different ways by different researchers. In this paper we will show how the family of Role-based Trust management languages (RT) can be used in WSN. RT is used for representing security policies and credentials in decentralized, distributed access control systems. A credential provides information about the privileges of users and the security policies issued by one or more trusted authorities.

4

Czasowa ważność poświadczeń języka RT T+

Felkner A., Kozakiewicz A.

Studia Informatica

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2011

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Vol. 32, nr 3A

145-154

PL

Język RT T należy do języków zarządzania zaufaniem z rodziny języków role-based trust management, który jest używany do reprezentowania polityk bezpieczeństwa oraz poświadczeń w rozproszonym upoważnianiu. Łączy on zalety kontroli dostępu, opartej na roli i systemów zarządzania zaufaniem. W artykule zaproponowano wprowadzenie ograniczeń czasowych ważności poświadczeń w języku RT T.

EN

The topic of this paper is RT T, a language from the family of RT languages, which is used for representing security policies and credentials in distributed access control systems. The goal of this paper is introduction of time validity constraints to show how that can make RT T language more realistic.