Defense Notices

Instructions executed by the processor are dynamically dead if the values they produce are not used by the program. Researchers have discovered that a surprisingly large fraction of executed instructions are dynamically dead. Dynamically dead instructions (DDI) can potentially slow-down program execution and waste power. Unfortunately, although the issue of DDI is well-known, there has not been any comprehensive study to understand and explain the occurence of DDI, evaluate its performance impact, and resolve the problem, especially for contemporary architectures. 
The goals of our research are to quantify and understand the properties of DDI, as well as, systematically characterize them for existinng state-of-the-art compilers and popular architectures in order to develop compiler and/or architectural techniques to avoid their execution at runtime. In this thesis, we describe our GCC-based framework to instrument binary programs to generate control-flow and data-flow (registers and memory) traces at runtime. We present the percentage of DDI in our benchmark programs, as well as, characteristics of the DDI. We display that context information can have a siginificant impact on the probability that an instruction will be dynamically dead. We show that a low percentage of static instructions actually contribute to the overall DDI in our benchmark programs. We also describe the outcome of our manual study to analyze and categorize the instances of dead instructions in our x86 benchmarks into seven distinct categories. We briefly describe our plan to develop compiler and architecture based techniques to eliminate each category of DDI in future programs. And finally, we find that x86 and ARM programs, compiled with GCC, generally contain a significant amount of DDI. However, x86 programs present fewer DDI than the ARM benchmarks, which display similar percentages of DDI as earlier research for other architectures. Therefore, we suggest that the ARM architecture observes a non-negligible fraction of DDI and should be examined further. Overall, we believe that a close synergy between static code generation and program execution techniques may be the most effective strategy to eliminate DDI.

With the extreme popularity of online social networks, security and privacy issues become critical. In particular, it is important to protect user privacy without preventing them from normal socialization. User privacy in the context of data publishing and structural re-identification attacks has been well studied. However, protection of attributes and data content was mostly neglected in the research community. While social network data is rarely published, billions of messages are shared in various social networks on a daily basis. Therefore, it is more important to protect attributes and textual content in social networks. 

We first study the vulnerabilities of user attributes and contents, in particular, the identifiability of the users when the adversary learns a small piece of information about the target. We have presented two attribute-reidentification attacks that exploit information retrieval and web search techniques. We have shown that large portions of users with online presence are very identifiable, even with a small piece of seed information, and the seed information could be inaccurate. 
To protect user attributes and content, we will adopt the social circle model derived from the concepts of “privacy as user perception” and “information boundary”. Users will have different social circles, and share different information in different circles. We propose to automatically identify social circles based on three observations: (1) friends in the same circle are connected and share many friends in common; (2) friends in the same circle are more likely to interact; (3) friends in the same circle tend to have similar interests and share similar content. We propose to adopt multi-view clustering to model and integrate such observations to identify implicit circles in a user’s personal network. Moreover, we propose an evaluation mechanism that evaluates the quality of the clusters (circles). 
Furthermore, we propose to exploit such circles for cross-site privacy protection for users –new messages (blogs, micro-blogs, updates, etc) will be evaluated and distributed to the most relevant circle(s). We monitor information distributed to each circle to protect users against information aggregation attacks, and also enforce circle boundaries to prevent sensitive information leakage.

Recent computing trends include an increased focus on power and energy consumption and the need to support multi-tenant use cases in which physical resources need to be multiplexed efficiently without causing performance interference. Many recent works have focused on how to best allocate CPU, storage and network resources to meet competing service quality objectives and reduce power. At the same time, data-intensive computing is placing larger demands on physical memory systems than ever before. In comparison to other resources, however, it is challenging to obtain precise control over distribution of memory capacity, bandwidth, or power, when virtualizing and multiplexing system memory. That is because these effects intimately depend upon the results of activity across multiple layers of the vertical execution stack, which are often not available in any individual component. 

The goal of our proposed work is to exercise collaboration between the compiler, operating system, and memory controller for a hybrid memory architecture to reduce energy consumption, while balancing performance trade-offs. Analysis, data structure partitioning, and code layout transformations will be conducted by the compiler and two-way communication between the applications and OS will guide memory management. The OS, together with the hardware memory controller, will allocate, map, and migrate pages to minimize energy consumption for a specified performance tolerance.

Ultra High frequency Radio Frequency Identification (UHF RFID) technology has gained wide prominence in recent years. The main drawback of a UHF RFID tag antenna is that it is sensitive to the environment in which it is placed. That is the performance of a RFID tag deteriorates when placed on conductive or dielectric objects. Most UHF RFID antennas use variations of a balanced folded dipole, such as a T-match antenna. In this project, we answer the question, would it be beneficial having an unbalanced version of a T-match antenna (Gamma match antenna) in a RFID tag compared to having a conventional balanced T-match antenna? To test this we analyzed the performance of a gamma match and T-match antenna, when attached to a charge pump, which generally acts as a load for a RFID antenna in a RFID tag. Also, we propose a procedure to find out the best impedance to drive a charge pump and outline a simple procedure to design a balanced T-match antenna for any desirable input impedance. Later, we transform a balanced T-match antenna into a unbalanced Gamma match antenna and tested to see that a Gamma match antenna is able to deliver more power and voltage to a charge pump than a T-match antenna. Finally we validate these results by studying and comparing the Z-parameters of a Gamma match and T-match antenna.

Information used to assist biomedical research has largely comprised of data available in published sources like scientific literature or clinical sources like patient health records. Information from such sources, though extensive and organized, is often not readily available due to its proprietary and/or privacy-sensitive nature. Collecting such information through clinical and pharmaceutical studies is expensive and the information is limited to the diversity of people involved in the study. With the growth of Web 2.0, more and more people openly share their health experiences with other similar patients on healthcare related social networks. The data available in these networks can act as a new source that provides for unrestricted, high volume, highly diverse and up-to-date information needed for assisting biomedical and pharmaceutical research. However, this data is often unstructured, noisy and scattered, making it unsuitable for use in its current form. The goal of this research is to develop an Information Retrieval and Knowledge Discovery framework that is capable of automatically collecting such data from online healtcare networks, extracting useful information and representing it in a form that would facilitate knowledge discovery in biomedical and pharmaceutical research. Information retrieval, Text mining and Ontology modeling techniques are employed in building this framework. An Adverse Drug Reaction discovery tool and a patient profiling tool are being developed to demonstrate the utility of this framework.

There are so many social network aggregators available in the market, e.g.SocialNetwork.in, FriedFeed, Pluggio, Postano, Hootsuite etc. A social network aggregator is a one-stop shop which provides a single point of entry to manage operations of multiple social network accounts and keep track of social media streams. Once a user establishes the sites credentials onto the aggregator, it pulls static data like user profile information, dynamic data like news feed and user posts. 

This project aims to design a unified interface of static and dynamic data from facebook, foursquare and twitter for a particular user. Unlike other social aggregators that display dynamic social media stream data in different tabs, each corresponding to a social networking site, we merge dynamic data like timeline from facebook and sent tweets from twitter together and display them on a single stream sorted according to the posting date. Similarly, news feed from facebook and twitter home are merged together and can be seen on a single stream. To simplify cross-social-network management, we support unified operations such as Posting. New posts/tweets can be easily posted at the same time on both the sites through this application. User can further specify the access privileges (i.e., seen by public, friends, friends of friends or only me) of the posts on Facebook, for dynamic privacy protection. 

Least but not last, this aggregator supports integration of user profiles from the three social networks. An edit distance based similarity score is calculated to determine the likelihood of profiles from three social networks belong to a same friend. For those with a perfect score, the matched profiles are combined and displayed in an additional dialog.

The Trusted Platform Module (TPM) serves as the root-of-trust in a trusted computing environment, and therefore warrants formal specification and verification. This thesis presents results of an effort to specify and verify an abstract TPM 1.2 model using PVS that is useful for understanding the TPM and verifying protocols that use it. TPM commands are specified as state transformations and sequenced to represent protocols using a state monad. Preconditions, postconditions, and invariants are specified for individual commands and validated. All specifications are written and verified automatically using the PVS decision procedures and rewriting system.

Software use is an inescapable reality. Computer systems are embedded into devices from the mundane to the complex and significantly impact daily life. Increased use expands the opportunity for malicious use which threatens security and privacy. Factors such as high profile data breaches, rising cost due to security incidents, competitive advantage and pending legislation are driving software developers to integrate security into software development rather than adding security after a product has been developed. Security requirements must be elicited, modeled, analyzed, documented and validated beginning at the initial phases of the software engineering process rather than being added at later stages. However, approaches to developing security requirements have been lacking which presents barriers to security requirements integration during the requirements phase of software development. In particular, software development organizations working within short development lifecycles (often characterized as agile lifecyle) and minimal resources need a light and practical approach to security requirements engineering that can be easily integrated into existing agile processes. 
In this thesis, we present an approach for eliciting, analyzing, prioritizing and developing security requirements which can be integrated into existing software development lifecycles for small, agile organizations. The approach is based on identifying candidate security goals, categorizing security goals based on security perspectives, understanding the stakeholder goals to develop preliminary security requirements and prioritizing preliminary security requirements. The identification activity implements part of speech tagging to scan requirements artifacts for security terminology to discover candidate security goals. The categorization activity applies a general security perspective to candidate goals. Elicitation activities are undertaken to gain a deeper understanding of the security goals from stakeholders. Elicited goals are prioritized using risk management techniques and security requirements are developed from validated goals. Security goals may fail the validation activity, requiring further iterations of analysis, elicitation, and prioritization activities until stakeholders are satisfied with or have eliminated the security requirement. Finally, candidate security requirements are output which can be further modeled, defined and validated using other approaches. A security requirements repository is integrated into our proposed approach for future security requirements refinement and reuse. We validate the framework through an industrial case study with a small, agile software development organization.

The design of a two-way active splitter requires background knowledge of discrete RF amplifier design and 3-port power divider design. These two design topics will sufficiently showcase the knowledge acquired thus far from previous graduate courses and show the ability to research/acquire the needed information to combine these two general topics into one design. The completed design will consist of a gain stage at the input of a 3-port power divider, and a gain stage at each output of the 3-port power divider. Matching networks will be required at the input/outputs of the design and also between the gain stages and 3-port power divider. The most important design considerations are: Bandwidth, Noise and Stability. The next critical design considerations are: Gain, DC requirements, S parameter flatness return loss and Group Delay. Once the NF, BW and Stability specifications are met, the amplifier will be adjusted to increase gain until the previous specs become violated. Gain is not as critical; the minimum gain required will only need to be greater than the insertion loss of the 3-port power divider and matching networks. The matching networks will be tuned to minimize NF; maximizing gain is not as important as minimizing NF. At this point the less important parameters will be verified/optimized. ADS will be used to simulate the design. The gain stage will be simulated and optimized first. Then the optimized gain stage will be added to the 3-port power divider input/outputs, along with the matching networks, to create the finalized simulation. Once the simulation of the entire design has been optimized it will be implemented similar to the simulation steps. Start with a milled PCB to test/optimize the gain stage. Then mill a PCB of the entire design and test/optimize it also. Throughout the simulation and implementation testing/optimizing the main design lessons learned/take aways will be presented and discussed. The main goal is to present the major design tradeoffs discovered throughout the design process.

Firewalls, network devices, and the access control lists that manage traffic are very important components of modern networking from a security and regulatory perspective. They provide the protection between networks that only wish to communicate over an explicit set of channels, expressed through the protocols, traveling over the network. 
In small test environments and networks, firewall policies may be easy to comprehend and understand; however, in real world organizations these devices and policies must be capable of handling large amounts of traffic traversing hundreds or thousands of rules in a particular policy. Therefore, the need for an organization to unerringly and deterministically understand what traffic is allowed through a firewall, while being presented with hundreds or thousands of rules and routes, is imperative. This dissertation investigates the comprehension of traffic flow through these complex devices by focusing on the following research 
topics: 
- Expands on how a security policy may be processed by decoupling the original rules from the policy, and instead allow a holistic understanding of the solution space being represented. 
- Introduces a new set of data structures and algorithms collectively referred to as a Firewall Policy Diagram (FPD). A structure that is capable of modeling Internet Protocol version 4 packet (IPv4) solution space in memory efficient, mathematically set-based entities. 
- Presents a concise, precise, and descriptive language called Firewall Policy Query Language (FPQL) as a mechanism to explore the space. FPQL is a Backus Normal Form (Backus-Naur Form) (BNF) compatible notation for a query language to do just that sort of exploration. It looks to translate concise representations of what the end user needs to know about the solution space, and extract the information from the underlying data structures. 
- Finally, this dissertation presents a behavioral model of the capabilities found in firewall type devices and a process for taking vendor-specific nuances to a common implementation. This includes understanding interfaces, routes, rules, translation, and policies; and modeling them in a consistent manner such that the many different vendor implementations may be compared to each other.