The goal of this research was to create a decentralized trust-based access control (TBAC) system for a dynamic collaborative environment (DCE). By building a privilege management infrastructure (PMI) based on trust, user access was determined using behavior grading without the need for pre-configured, centrally managed role hierarchies or permission sets. The PMI provided TBAC suitable for deployment in a rapidly assembled, highly fluid, collaborative environment. DCEs were assembled and changed membership as required to achieve the goals of the group. A feature of these environments was that there was no way of knowing who would join the group, no way of refusing anyone entry into group, and no way of determining how long members would remain in the group. DCEs were formed quickly to enable participants to share information while, at the same time, allowing them to retain control over the resources that they brought with them to the coalition. This research progressed the state of the art in the fields of access control and trust management. The Trust Management System developed through this research effectively implemented a decentralized access control scheme. Each resource owner independently evaluated the reputation and risk of network members to make access decisions. Because the PMI system used past behavior as an indication of future performance, no a priori user or resource configuration was required. / Ph. D.

With the progression of computer networks extending boundaries and joining distant locations, wireless sensor networks (WSNs) emerge as the new frontier in developing opportunities to collect and process data from remote locations. WSNs rely on hardware simplicity to make sensor field deployments both affordable and long-lasting without maintenance support. WSN designers strive to extend network lifetimes while meeting application-specific throughput and latency requirements. Effective power management places sensor nodes into one of the available energy-saving modes based upon the sleep period duration and the current state of the radio. This research investigates energy-efficient medium access control (MAC) protocols designed to extend both the lifetime and range of wireless sensor networks. These networks are deployed in remote locations with limited processor capabilities, memory capacities, and battery supplies. The purpose of this research is to develop a new medium access control protocol which performs both cluster management and inter-network gateway functions in an energy-efficient manner. This new protocol, Gateway MAC (GMAC), improves on existing sensor MAC protocols by not only creating additional opportunities to place the sensor platforms into lower power-saving modes, but also by establishing a traffic rhythm which extends the sleep duration to minimize power mode transition costs. Additionally, this research develops a radio power management (RPM) algorithm to provide a new mechanism for all WSN MAC protocols to optimize sleep transition decisions based upon the power and response characteristics of the sensor platform's transceiver. Finally, to extend access to sensor data in remote locations, this research also validates an innovative wireless distribution system which integrates wireless sensor networks, mobile ad hoc networks (MANET), and the Internet. This research makes two significant contributions to the state-of-the-art wireless sensor networks. First, GMAC's centralized network management function offers significant energy savings and network lifetime extensions over existing wireless sensor network protocols. The second contribution is the introduction of a wireless sensor radio power management algorithm designed to exploit additional power-saving opportunities introduced with the newest generation of faster sensor platform transceivers. / Ph. D.

The selection of an input method to allow computer access by persons with disabilities is currently done by trained personnel; however, the selection process is unsystematic, subjective, and plagued with problems. This research has attempted to develop a systematic method, based on objective measures of an individual's hand skills, for selecting a computer input device. Each input device being considered was evaluated to determine the probable basic elements of motor performance which contribute to successful operation of the device. Subjects in the study consisted of individuals with various degrees of functional limitations of their upper extremities. Subjects first underwent a specially-developed motor assessment test designed to measure each of the motor functions identified as contributing to the operation and control of the input devices. Each subject then performed a series of computer-based tasks with each input device. The task itself was a modified target acquisition task with the independent variables of target size, target distance, mode (button up vs. button down (i.e. point vs. drag moves)), and trial block. The participants’ scores on both the assessment test and each device were analyzed in order to form the relationships between the two sets of scores. Results show that : 1) By analyzing a prospective input device with respect to the physical actions necessary for operation, and comparing an individual's scores on the subtests of the motor function assessment which correspond to those necessary actions, the test administrator can immediately identify actions which may be necessary, but which are extremely difficult or unavailable. If no discrepancies between the available and required actions exist, then one can conclude that the device is operable by the client. 2) Where discrepancies do exist between what a client can do and what a device requires, the assessment test targets the specific actions which create the difficulty. As a result, one can then recommend modifications to the device which may lead to the client being able to operate the device. 3) Finally, the effects of task parameters such as target size, target distance, and the effects of practice were determined for persons with different levels of hand skill (as measured by the assessment test). In general, persons with limited hand skill require only slightly longer to become proficient with a device than persons without disabilities. The rank ordering of the five devices tested with respect to input rates achievable was the same for persons with and without disabilities. Persons with disabilities were, as expected, slower overall with each device. In general, the trackball, mouse, and tablet resulted in better performance than the keys or joystick, for persons with and without disabilities. Persons with limited hand skill were more affected by the task parameter of target size on all devices, particularly for button down moves. Regardless of disability level, persons generally preferred the trackball over the remaining devices, and rated the joystick as being less preferable than the other devices. This research not only developed guidelines concerning the five devices selected for use in this study, but also serves to demonstrate the feasibility and utility of an accommodative aid selection system based on a functional assessment of the client's residual abilities. In addition, this research provides important information to hardware and software manufacturers regarding accessibility issues. / Ph. D.

In most conventional computer environments an increase in complexity of security mechanisms for greater precision and resolution can possibly degrade the performance of the system. Also, security checking which is often embedded In the operating system, database management system, or both is difficult to change and verify. This dissertation presents a new system architecture that can possibly solve many of the problems of protection and security found in a conventional environment. This new system is a MULTIprocessor system for supporting Secure Authorization with Full Enforcement (MULTISAFE) for database management. The architecture of MULTISAFE combines the concepts of multiprocessing, pipelining, and parallelism to form a new system organization. The system's organization ls partitioned into three modules: the user and application module (UAM), the data storage and retrieval module (SRM), and the protection and security module (PSM). Each module is viewed as being implemented on one or more hardware (or virtual) processors with its own memory. The system organization incorporates a multiport-memory organization with private memories. A memory is made "private" by connecting only certain processors to it thereby providing physical separation between the UAM memory and the PSM and SRM memories. This separation (or isolation) can significantly improve security because it is physically impossible for a user to access the PSM or the SRM memories. System performance can possibly be enhanced by concurrent processing. The modules (or processors) require direct communication among themselves and the system users. Because of this communication requirement MULTISAFE is viewed as a message-driven, dataflow system. The majority of this dissertation focuses on the flow of messages and on showing that this flow is secure. To have secure message flow in MULTISAFE all messages are classified, and all message sequences are identified. All messages are classified by five attributes (class, source, target, type, and subtype). Message sequences are formed by the receiving and sending of messages. That is, the target module of the received message becomes the source of the sent message. Message sequences begin with a user’s access request and ends with a response for that request. Such sequences are called round-trip message sequences. Once the messages and their flow have been described, it is then possible to describe how each MULTISAFE module monitors its own messages. The monitoring of messages follows the pattern of receiving a message, processing the message, and sending a message. These three dataflow components are described as abstract data operations on the data object message. These operations are then used to describe the monitoring procedure for each module. Each module monitor is basically a table look-up process which uses the classification of the received message as the table index for determining the next message to be sent. The proof that message flow is secure consists of showing that every message in MULTISAFE is part of a message sequence and. that every message sequence is part of a round-trip message sequence. The proof culminates by showing that an access decision is made on all MULTISAFE round-trip message sequences. / Ph. D.

M. S.

Designers, operators, and users of multiple-device, access control security systems are challenged by the false alarm, false clear tradeoff. Given a particular access control security system, and a prespecified false clear standard, there is an optimal (minimal) false alarm rate that can be achieved. The objective of this research is to develop methods that can be used to determine this false alarm rate. Meeting this objective requires knowledge of the joint conditional probability density functions for the security device responses. Two sampling procedures, the static grid estimation procedure and the dynamic grid estimation procedure, are proposed to estimate these functions. The concept of a system response function is introduced and the problem of determining the optimal system response function that minimizes the false alarm rate, while meeting the false clear standard, is formulated as a decision problem and proven to be NP-complete. Two heuristic procedures, the Greedy algorithm and the Dynamic Programming algorithm, are formulated to address this problem. Computational results using simulated security data are reported. These results are compared to analytical results, obtained for a prespecified system response function form. Suggestions for future research are also included. / Master of Science

This paper describes the performance of the MULTISAFE database protection model through response-time equations. A predicate-based protection model is described. Various classes of access decision dependencies are reviewed. The distinct modules of MULTISAFE are discussed, and a relational database approach to the management of data protection is developed for these modules. A performance equation which models user login into MULTISAFE is developed. A set of equations is developed which model the processing of database queries as a series of steps. These equations are then modified to consider the possibility of concurrent processing among the MULTISAFE modules. The two sets of equations are compared and analyzed. The analysis reveals that the concurrency feature of MULTISAFE allows database protection to be implemented with a minimum of system overhead. Further analysis shows that, in some cases, an arbitrary database query takes less time to process with all protection checks in force than a similar query in a protection less environment. / Master of Science

Yes / Web of Things (WoT) can be considered as a merger of newly emerging paradigms of Internet of Things (IoT) and cloud computing. Rapidly varying, highly volatile and heterogeneous data traffic is a characteristic of the WoT. Hence, the capture, processing, storage and exchange of huge volumes of data is a key requirement in this environment. The crucial resources in the WoT are the sensing devices and the sensing data. Consequently, access control mechanisms employed in this highly dynamic and demanding environment need to be enhanced so as to reduce the end-to-end latency for capturing and exchanging data pertaining to these underlying resources. While there are many previous studies comparing the advantages and disadvantages of access control mechanisms at the algorithm level, vary few of these provide any detailed comparison the performance of these access control mechanisms when used for different data handling procedures in the context of data capture, processing and storage. This study builds on previous work on token-based access control mechanisms and presents a comparison of two different approaches used for handling sensing devices and data in the WoT. It is shown that the aggregated data submission approach is around 700% more efficient than the serial payload submission procedure in reducing the round-trip response time.

<p>U tezi je analiziran problem kontrole pristupa u Smart Grid sistemima. Formalno je specificiran model kontrole pristupa za Smart Grid koji je zasnovan na unapređenju i proširenju RBAC modela i koji je usklađen sa aktuelnim zahtevima u elektroenergetskoj industriji. Postavljena je softverska arhitektura predloženog modela kontrole pristupa, čija je prototipska implementacija zatim integrisana u simuliranom Smart Grid okruženju.</p> / <p>This thesis discusses the challenges related to access control in Smart<br />Grid systems. A formal model for access control in the Smart Grid is<br />specified, extending the role-based access control (RBAC) model to be<br />in accordance with the existing security requirement in the power industry.<br />Based on the proposed access control model, software architecture was<br />developed and its prototype implementation is integrated in a Smart Grid<br />simulated environment.</p>

Privacy concerns have always been present in every society. The introduction of information technology information has enabled a reduction in the cost of gathering information, management of that information and the permitted that same information to become increasingly portable. Coupled with these reductions of cost has been an increase in the demand for information as well as the concern that privacy expectations be respected and enforced through security systems that safeguard access to private-type data. Security systems enforce privacy expectations. Unfortunately there is no consensus on a definition of privacy making the specification of security often over broad and resulting in the loss of critical functionality in the systems produced. This research expands the understanding of privacy by proposing a replicable type-based taxonomy of privacy that is grounded in philosophy and law. This type-based system is applied to a Role Based Access Control System to specify and control access to data in a in a hospital setting as a proof of concept.