scholarly journals Distributed Approximation of Fixed-Points in Trust Structures

2015 ◽  
Vol 12 (6) ◽  
Author(s):  
Karl Krukow ◽  
Andrew Twigg
Keyword(s):  
Fixed Point ◽  
Trust Management ◽  
Mathematical Object ◽  
Global Scale ◽  
Semantic Model ◽  
Precise Meaning ◽  
Structure Framework ◽  
Dynamic Trust ◽  
Partial Orderings ◽  
Distributed Approximation

Recently, Carbone, Nielsen and Sassone introduced the trust-structure framework; a semantic model for trust-management in global-scale distributed systems. The framework is based on the notion of trust structures; a set of ``trust-levels'' ordered by two distinct partial orderings. In the model, a unique global trust-state is defined as the least fixed-point of a collection of local policies assigning trust-levels to the entities of the system. However, the framework is a purely denotational model: it gives precise meaning to the global trust-state of a system, but without specifying a way to compute this abstract mathematical object.<br /> <br /> This paper complements q the denotational model of trust structures with operational techniques. It is shown how the least fixed-point can be computed using a simple, totally-asynchronous distributed algorithm. Two efficient protocols for approximating the least fixed-point are provided, enabling sound reasoning about the global trust-state without computing the exact fixed-point. Finally, dynamic algorithms are presented for safe reuse of information between computations, in face of dynamic trust-policy updates.

scholarly journals Distributed Approximation of Fixed-Points in Trust Structures

2004 ◽  
Vol 11 (16) ◽  
Author(s):  
Karl Krukow ◽  
Andrew Twigg
Keyword(s):  
Fixed Point ◽  
Fixed Points ◽  
Distributed Algorithm ◽  
Partial Information ◽  
Mathematical Object ◽  
Continuous Functions ◽  
Formal Models ◽  
Global Computing ◽  
Dynamic Trust ◽  
Distributed Approximation

Recently, developments of sophisticated formal models of trust in large distributed environments, incorporate aspects of partial information, important e.g. in global-computing scenarios. Specifically, the framework based on the notion of trust structures, introduced by Carbone, Nielsen and Sassone, deals well with the aspect of partial information. The framework is ``denotational'' in the sense of giving meaning to the global trust-state as a unique, abstract mathematical object (the least fixed-point of a continuous function). We complement the denotational framework with ``operational'' techniques, addressing the practically important problem of approximating and computing the semantic objects. We show how to derive from the setting of the framework, a situation in which one may apply a well-established distributed algorithm, due to Bertsekas, in order to solve the problem of computation and approximation of least fixed-points of continuous functions on cpos. We introduce mild assumptions about trust structures, enabling us to derive two theoretically simple, but highly useful propositions (and their duals), which form the basis for efficient protocols for sound approximation of the least fixed-point. Finally, we give dynamic algorithms for safe reuse of information between computations, in face of dynamic trust-policy updates.

scholarly journals Dynamic Trust Management for Community Based Mobile Grid Application

2019 ◽  
Vol 9 (2) ◽  
pp. 4458-4462
Keyword(s):  
Data Security ◽  
Trust Management ◽  
User Privacy ◽  
Community Based ◽  
Mobile Grid ◽  
Management Protocol ◽  
Dynamic Trust ◽  
Misbehaving Nodes ◽  
Collection Data ◽  
Grid Application

Mobile Grid is the inter-networking of heterogeneous physical as well as virtualdevices. Each device transfer and share the information with each other. Trust management plays a significant role in network based applications for information collection, data mining, qualified services with context-awareness, upgraded client protection and data security. It assists individuals with beating impression of vulnerability, threat and participates in client acknowledgment to utilization on grid services and applications. In this paper a unique trust management protocol is proposed for network based mobile grid application to manage misbehaving nodes whose status or performance may change dynamically. Trust plays an important role for handling the security in the community based system. Trust management provides facilitate to identify malfunctions and also make legitimate collaboration and enhance the user privacy and information security.

scholarly journals A Novel Iterative and Dynamic Trust Computing Model for Large Scaled P2P Networks

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Zhenhua Tan ◽  
Xingwei Wang ◽  
Xueyi Wang
Keyword(s):  
Trust Management ◽  
Trust Model ◽  
Computation Method ◽  
Collusion Attack ◽  
Communication Architecture ◽  
P2p Systems ◽  
Iterative Computation ◽  
Main Challenge ◽  
Dynamic Trust ◽  
Complementary Part

Trust management has been emerging as an essential complementary part to security mechanisms of P2P systems, and trustworthiness is one of the most important concepts driving decision making and establishing reliable relationships. Collusion attack is a main challenge to distributed P2P trust model. Large scaled P2P systems have typical features, such as large scaled data with rapid speed, and this paper presented an iterative and dynamic trust computation model named IDTrust (Iterative and Dynamic Trust model) according to these properties. First of all, a three-layered distributed trust communication architecture was presented in IDTrust so as to separate evidence collector and trust decision from P2P service. Then an iterative and dynamic trust computation method was presented to improve efficiency, where only latest evidences were enrolled during one iterative computation. On the basis of these, direct trust model, indirect trust model, and global trust model were presented with both explicit and implicit evidences. We consider multifactors in IDTrust model according to different malicious behaviors, such as similarity, successful transaction rate, and time decay factors. Simulations and analysis proved the rightness and efficiency of IDTrust against attacks with quick respond and sensitiveness during trust decision.

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