Evidence Combination in an Environment With Heterogeneous Sources

A framework for the combination of evidence in an environment where data are generated from heterogeneous sources possessing partial or incomplete knowledge about the global network scenario is presented. The approach taken is based on the conditional belief and plausibility notions in Dempster-Shafer evidence theory that allow one to condition these partial knowledge bases so that only that portion of the incoming evidence that is relevant is utilized for updating an existing knowledge base. The strategy proposed enables one to accommodate some of the most challenging, yet essential, features that are encountered when evidence is generated from possibly a large numbers of sources. These include heterogeneity and reliability of incoming evidence, inertia and integrity of evidence already gathered, and potentially limited resources at the nodes where evidence updating is carried out. The proposed framework is applied in robot map discovery using ultrasonic sensors and a real-world scenario where sensor data generated by heterogeneous sensors are used for potential threat carrier-type detection     

SS7 over IP: signaling interworking vulnerabilities

Public telephony - the preferred choice for two-way voice communication over a long time - has enjoyed remarkable popularity for providing acceptable voice quality with negligible connection delays, perhaps due to its circuit-switched heritage. Recently, IP telephony, a packet-based telephone service that runs as an application over the IP protocol, has been gaining popularity. To provide seamless interconnectivity between these two competing services, the Internet Engineering Task Force (IETF) has designed a signaling interface commonly referred to as SIGTRAN. This seamless intersignaling provided by SIGTRAN facilitates any subscriber in one network to reach any other subscriber in the other network, passing through any heterogeneous maze of networks consisting of either of these. Unfortunately, the same intersignaling potentially can be exploited from either side to disrupt the services provided on the other side. We show how this can be done and propose a solution based on access control, signal screening, and detecting anomalous signaling. We argue that to be effective, the latter two should consider syntactic correctness, semantic validity of the signal content, and the appropriateness of a particular signal in the context of earlier exchanged messages     

Reasoning with advanced policy rules and its application to access control

This paper presents a formal framework to represent and manage advanced policy rules, which incorporate the notions of provision and obligation. Provisions are those conditions that need to be satisfied or actions that must be performed by a user or an agent before a decision is rendered, while obligations are those conditions or actions that must be fulfilled by either the user or agent or by the system itself within a certain period of time after the decision. This paper proposes a specific formalism to express provisions and obligations within a policy and investigates a reasoning mechanism within this framework. A policy decision may be supported by more than one rule-based derivation, each associated with a potentially different set of provisions and obligations (called a global PO set). The reasoning mechanism can derive all the global PO sets for each specific policy decision and facilitates the selection of the best one based on numerical weights assigned to provisions and obligations as well as on semantic relationships among them. The formal results presented in the paper hold for many applications requiring the specification of policies, but this paper illustrates the use of the proposed policy framework in the security domain only.     

Security requirement derivation by noun–verb analysis of use–misuse case relationships: a case study using positive train control

Use cases and misuse cases, respectively, state the interactions that an actor can have and a mal-actor be prevented from having with a system. The cases do not specify either the security requirements or the associated attributes that a system must possess to operate in a secure manner. We present an algorithmic, domain-independent approach rooted in verb–noun analysis of use cases and misuse cases to generate system requirements and the associated security attributes. We illustrate the utility of this general five-step method using Positive train control (PTC) (a command and control system used to navigate trains in a railway grid) as a case study. This approach allows the designer to protect against the effect of wireless vulnerabilities on the safety of PTC systems.     

Structural and electronic properties of fluorographene

The structural and electronic characteristics of fluorinated graphene are investigated based on first-principles density-functional calculations. A detailed analysis of the energy order for stoichiometric fluorographene membranes indicates that there exists prominent chair and stirrup conformations, which correlate with the experimentally observed in-plane lattice expansion contrary to a contraction in graphane. The optical response of fluorographene is investigated using the GW-Bethe-Salpeter equation approach. The results are in good conformity with the experimentally observed optical gap and reveal predominant charge-transfer excitations arising from strong electron-hole interactions. The appearance of bounded excitons in the ultraviolet region can result in an excitonic Bose-Einstein condensate in fluorographene.     

An authorization model for multimedia digital libraries

In this paper we present a generalized authorization model for multimedia digital libraries. Our aim is to support the enforcement of access control requirements of the original data sources without the need to create a new, unified model for the digital library. We integrate the three most widely used access control models (i.e., mandatory, discretionary, and role-based) within a single framework, allowing seamless accesses to data protected by these security models. In particular, we address the access control needs of continuous media data while supporting quality of service (QoS) requirements and preserving operational semantics. The technical core of the paper focuses on the development of metadata and the corresponding metastructure to represent authorization policies and QoS requirements and shows their applicabilty to continuous media. We define our security objects based on the Synchronized Multimedia Integration Language (SMIL), which controls multimedia presentations. Following the synchronization constructs par and seq of SMIL, we define a normal form for multimedia streams, called SMIL normal form. SMIL normal form provides a syntax-independent representation of semantically equivalent multimedia data. SMIL normal form compositions are extended (decorated) with RDF statements, representing security and QoS metadata. Interpretation of these statements and, therefore, the authorization and QoS requirements of the decorated multimedia object are defined by the metastructure, represented as a DAML+OIL ontology. We propose the concept of generalized subject that encompasses all access permissions of a given user regardless of the multiple permissions in different access control models. Finally, we develop methods to generate secure views for each generalized subject and retrieve them using a secure multimedia server.     

Provisions and Obligations in Policy Rule Management

Policies in modern systems and applications play an essential role. We argue that decisions based on policy rules should take into account the possibility for the users to enable specific policy rules, by performing actions at the time when decisions are being rendered, and/or by promising to perform other actions in the future. Decisions should also consider preferences among different sets of actions enabling different rules. We adopt a formalism and mechanism devised for policy rule management in this context, and investigate in detail the notion of obligations, which are those actions users promise to perform in the future upon firing of a specific policy rule. We also investigate how obligations can be monitored and how the policy rules should be affected when obligations are either fulfilled or defaulted.