Simin Hall

Interlocking obfuscation for anti-tamper hardware

Tampering and Reverse Engineering of a chip to extract the hardware Intellectual Property (IP) core or to inject malicious alterations is a major concern. Digital systems susceptible to tampering are of immense concern to defense organizations. First, offshore chip manufacturing allows the design secrets of the IP cores to be transparent to the foundry and other entities along the production chain. Second, small malicious modifications to the design may not be detectable after fabrication without anti-tamper mechanisms. Some techniques have been developed in the past to improve the defense against such attacks but they tend to fall prey to the increasing power of the attacker. We present a new way to protect against tampering by a clever obfuscation of the design, which can be unlocked with a specific, dynamic path traversal. Hence, the functional mode of the controller is hidden with the help of obfuscated states, and the functional mode is made operational only on the formation of a specific interlocked Code-Word during state transition. No comparator is needed as the obfuscation is embedded within the transition function of the state machine itself. A side benefit is that any small alteration will be magnified via the obfuscated design. In other words, an alteration to the design will manifest itself as a large difference in the circuits functionality. Experimental results on an Advanced Encryption Standard (AES) circuit from the open-source IP-cores suite suggest that the proposed method provides better active defense mechanisms against attacks with nominal (7.8%) area overhead.

A novel statistical and circuit-based technique for counterfeit detection in existing ICs

Previously used ICs, which are resold as new, result in undue lost revenue, cause lower performance, reduced life span, and even catastrophic failure of platforms and systems. Non-invasive and inexpensive techniques are needed to establish the authenticity of such ICs that do not have special in-built structures for counterfeit detection. Although delay of circuit increases with its age, it cannot directly reveal the age of the chip, as it is also greatly influenced by process variation. In this work, we show that the relationship between two or more paths within the chip is a great indicator of its age. Using the proposed statistical and circuit-level technique, we observe over 97% correct detection of an aged IC from a new IC.

Fundamental features of a unified trust model for distributed systems

Trust and trustworthiness are significant measurements of a distributed sensing system or a heterogeneous network comprised of sources of information, knowledge, hardware and software. In an effort to design a unified trust model that can be made adaptable to changing application environments, we present fundamental features and rules extracted from literature pertaining to wireless sensor networks, social networks, e-commerce, mobile ad-hoc, peer-to-peer, and distributed network services. The design constraints are: it must (a) support a heterogeneous network, (b) obtain and evaluate multiple trustworthiness measures, (c) be carried out with computational ease without extensive computational power from the sensor network, and (d) be conceptually simple but have a firm basis in theory.

Review of trust research from an interdisciplinary perspective - psychology, sociology, economics, and cyberspace

Trust and trustworthiness apply to a wide range of applications in automation and human interactions. Their definitions and characteristics vary depending on the context and the situation. Nevertheless, they are significant because of risk, vulnerability, uncertainty, and confidence. In this paper we review past work to converge our understanding of Trust (human centric and subjective) and trustworthiness (hardware/software centric and objective) across fields including literature from psychological, sociological, economic, automation, and cyberspace perspectives of trust. We expect to create a more rigorous definition of trust and trustworthiness that leads to finding the appropriate metrics to measure trust and trustworthiness dynamically.

Our First Online Offering of Introduction to Thermal-Fluid Engineering

In this paper the researchers reflect on the use of various communication technologies from the first online offering of our introductory thermodynamics course. The asynchronous (i.e., forums) and synchronous communication technologies such as Centra™ were employed for instruction and explication of useful feedback and self-explanation to promote students’ collaboration. The instructors outline the types of questions used in these guided activities that challenged students to search for multiple ways to demonstrate their conceptual understanding of very fundamental physical notions. The discussion in this paper outlines ways to improve forum questions, instructor’ feedback, and the frequency of the feedback to improve students’ metacognitive strategies in learning and the application of the course material. The observational data are also examined to note if there were any differences in forum contributions online versus students’ contributions in a face-to-face class. This paper provides a platform for research about learning and evaluation of instruction in abstract engineering courses in an online environment. The study is significant and of interest to faculty and administrators who have taught courses in traditional classrooms and who are now considering online teaching to increase access to engineering education.© 2011 ASME

Online Course Design Informed by Students’ Epistemic Beliefs: A Case Study of a Thermodynamics Course

Online offerings of abstract engineering courses such as thermodynamics provide a medium to present course material using pedagogy that employs problem-based learning (PBL). This shift requires a student-centered approach to course design and delivery that addresses several key elements in the educational setting, including students’ self-efficacy as it relates to problem-solving and students’ epistemic beliefs as they relate to interacting with peers, instructors, and instruction. This paper reports results from a mixed-method study that collected data useful in design of an online course focused on teaching problem solving skills among students. The data were collected through qualitative and quantitative methods used to determine how students approach problem solving, the role of instructor in facilitating problem solving, and the role of peers and students’ use of technology as it relates to accomplishing course work related to problem solving. Results reveal that students are confident in their problem-solving skills but rely primarily on the instructor to show them how to solve problems. Analysis and discussion focus on how to change the manner in which the content of the course is designed and presented to improve students’ self-efficacy in problem solving and students’ epistemic beliefs through active engagement with materials and collaboration with peers and instructor.Copyright

Anti-counterfeit Integrated Circuits using fuse and tamper-resistant time-stamp circuitry

Counterfeit Integrated Circuits (ICs) have become an important security issue in recent years, in which counterfeit ICs that perform incorrectly or sub-par to the expected can lead to catastrophic consequences in safety and/or mission-critical applications, in addition to the tremendous economic toll they incur to the semiconductor industry. In this paper, we propose two novel methods to validate the authenticity of ICs. First, a fuse with a charge pump is proposed to serve as a “seal” for the IC, in which any functional use will break the seal, and the broken seal is extremely hard to replace. Second, a novel time-stamp is proposed that can provide the date at which the IC was manufactured. The time-stamp circuitry is constructed using a Linear-Feedback Shift-Register (LFSR) such that any small change to the circuit would result in an entirely different date either in a distant past or future, beyond the lifetime of a typical IC. Furthermore, we propose a second layer of tamper resistance to the time-stamp circuit to make it even more difficult to modify. Results show that with about 8.8% area overhead in AES implementation, the adversary requires more than 10118 different trials to successfully tamper time-stamp circuit. These techniques are easy to implement and embed into the circuit using todays technologies, while extremely difficult to modify or tamper with by the adversary. Finally, the method can be combined with additional hardware to detect malicious alteration made in the circuit.

Features of a Trust Model for a Complex System

This research focuses on trustworthiness assessment and trust judgment in a complex system such as a distributed sensing system. In our previous IMECE paper, we employed an interdisciplinary approach to highlight trustworthiness characteristics and trust measurements in social sciences and cyberspace. In this paper, we elaborate on these findings and present features of existing models we can leverage in different applications. Trust properties and rules reported in this study are extracted from three classes of trust models that met our design constraints. These models are gleaned from the literature pertaining to wireless sensor networks, social networks, e-commerce, mobile ad-hoc, peer-to-peer, and distributed network services. The trust model provides upfront quantitative assurance and trustworthiness metrics for architecting/engineering new systems as well as a situation awareness/management assessment metrics once the system is deployed.Copyright

Initial Results From an Interdisciplinary Review of Trust Research

In the days of modern engineering, a complex system can be designed and built using numerous sources of information, knowledge, hardware, and software. A factor that impacts the success of a complex system is trust. In designing a framework that allows for a unified trust model or trusting picture and defining a reliable metric for measuring trustworthiness, we are examining definitions and methodologies from social sciences and engineering. This paper uses a combination of publication analysis of research literature including psychological, sociological, economic, automation, and cyberspace perspectives of trust and technical dialogues with the subject matter experts at the Air Force Research Laboratory, to illuminate the interdisciplinary approach undertaken in hardware centric design with human interface. We review past work to highlight trustworthiness characteristics and trust measurements that conceptually could apply across fields under examination. We expect to create a more rigorous definition of trust and trustworthiness that leads to finding the appropriate metrics to measure trust and trustworthiness dynamically.Copyright

A trustworthiness evaluation framework for distributed networks

This research examines the utility of Markov switching models in assessing trust and trustworthiness of a heterogeneous network, e.g. distributed sensor networks. As an unsupervised machine learning method, hidden Markov models (HMM) is independent of the assumptions commonly used in modeling trust in complex systems. A relevant time series that switches regimes from trusted to untrusted periods of times is simulated to illustrate the theory of HMM and its effectiveness in Trust modeling. In this paper, we have employed HMM to estimate the parameters of a unified trust model that could make continual determinations of the trustworthiness of the data collected in any application environment. The results indicate that this method could effectively accommodate the desired features of our specified trust model despite various noises and uncertainties in the input signal. This study, by defining a new metric of trustworthiness and using HMM, provides an improvement over past studies in terms of computation costs, accuracy of estimation and forecasting, less a priori assumptions, and system agnosticism.