Visible to the public Biblio

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2021-04-09
Lin, T., Shi, Y., Shu, N., Cheng, D., Hong, X., Song, J., Gwee, B. H..  2020.  Deep Learning-Based Image Analysis Framework for Hardware Assurance of Digital Integrated Circuits. 2020 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA). :1—6.
We propose an Artificial Intelligence (AI)/Deep Learning (DL)-based image analysis framework for hardware assurance of digital integrated circuits (ICs). Our aim is to examine and verify various hardware information from analyzing the Scanning Electron Microscope (SEM) images of an IC. In our proposed framework, we apply DL-based methods at all essential steps of the analysis. To the best of our knowledge, this is the first such framework that makes heavy use of DL-based methods at all essential analysis steps. Further, to reduce time and effort required in model re-training, we propose and demonstrate various automated or semi-automated training data preparation methods and demonstrate the effectiveness of using synthetic data to train a model. By applying our proposed framework to analyzing a set of SEM images of a large digital IC, we prove its efficacy. Our DL-based methods are fast, accurate, robust against noise, and can automate tasks that were previously performed mainly manually. Overall, we show that DL-based methods can largely increase the level of automation in hardware assurance of digital ICs and improve its accuracy.
2021-03-30
Tai, J., Alsmadi, I., Zhang, Y., Qiao, F..  2020.  Machine Learning Methods for Anomaly Detection in Industrial Control Systems. 2020 IEEE International Conference on Big Data (Big Data). :2333—2339.

This paper examines multiple machine learning models to find the model that best indicates anomalous activity in an industrial control system that is under a software-based attack. The researched machine learning models are Random Forest, Gradient Boosting Machine, Artificial Neural Network, and Recurrent Neural Network classifiers built-in Python and tested against the HIL-based Augmented ICS dataset. Although the results showed that Random Forest, Gradient Boosting Machine, Artificial Neural Network, and Long Short-Term Memory classification models have great potential for anomaly detection in industrial control systems, we found that Random Forest with tuned hyperparameters slightly outperformed the other models.

2021-03-29
Alabugin, S. K., Sokolov, A. N..  2020.  Applying of Generative Adversarial Networks for Anomaly Detection in Industrial Control Systems. 2020 Global Smart Industry Conference (GloSIC). :199–203.

Modern industrial control systems (ICS) act as victims of cyber attacks more often in last years. These cyber attacks often can not be detected by classical information security methods. Moreover, the consequences of cyber attack's impact can be catastrophic. Since cyber attacks leads to appearance of anomalies in the ICS and technological equipment controlled by it, the task of intrusion detection for ICS can be reformulated as the task of industrial process anomaly detection. This paper considers the applicability of generative adversarial networks (GANs) in the field of industrial processes anomaly detection. Existing approaches for GANs usage in the field of information security (such as anomaly detection in network traffic) were described. It is proposed to use the BiGAN architecture in order to detect anomalies in the industrial processes. The proposed approach has been tested on Secure Water Treatment Dataset (SWaT). The obtained results indicate the prospects of using the examined method in practice.

2021-03-22
Larasati, H. T., Kim, H..  2020.  Simulation of Modular Exponentiation Circuit for Shor's Algorithm in Qiskit. 2020 14th International Conference on Telecommunication Systems, Services, and Applications (TSSA. :1–7.
This paper discusses and demonstrates the construction of a quantum modular exponentiation circuit in the Qiskit simulator for use in Shor's Algorithm for integer factorization problem (IFP), which is deemed to be able to crack RSA cryptosystems when a large-qubit quantum computer exists. We base our implementation on Vedral, Barenco, and Ekert (VBE) proposal of quantum modular exponentiation, one of the firsts to explicitly provide the aforementioned circuit. Furthermore, we present an example simulation of how to construct a 7xmod 15 circuit in a step-by-step manner, giving clear and detailed information and consideration that currently not provided in the existing literature, and present the whole circuit for use in Shor's Algorithm. Our present simulation shows that the 4-bit VBE quantum modular exponentiation circuit can be constructed, simulated, and measured in Qiskit, while the Shor's Algorithm incorporating this VBE approach itself can be constructed but not yet simulated due to an overly large number of QASM instructions.
2021-03-16
Li, M., Wang, F., Gupta, S..  2020.  Data-driven fault model development for superconducting logic. 2020 IEEE International Test Conference (ITC). :1—5.

Superconducting technology is being seriously explored for certain applications. We propose a new clean-slate method to derive fault models from large numbers of simulation results. For this technology, our method identifies completely new fault models – overflow, pulse-escape, and pattern-sensitive – in addition to the well-known stuck-at faults.

2021-03-15
Wang, F., Zhang, X..  2020.  Secure Resource Allocation for Polarization-Based Non-Linear Energy Harvesting Over 5G Cooperative Cognitive Radio Networks. ICC 2020 - 2020 IEEE International Conference on Communications (ICC). :1–6.
We address secure resource allocation for the energy harvesting (EH) based 5G cooperative cognitive radio networks (CRNs). To guarantee that the size-limited secondary users (SUs) can simultaneously send the primary user's and their own information, we assume that SUs are equipped with orthogonally dual-polarized antennas (ODPAs). In particular, we propose, develop, and analyze an efficient resource allocation scheme under a practical non-linear EH model, which can capture the nonlinear characteristics of the end-to-end wireless power transfer (WPT) for radio frequency (RF) based EH circuits. Our obtained numerical results validate that a substantial performance gain can be obtained by employing the non-linear EH model.
2021-03-09
MATSUNAGA, Y., AOKI, N., DOBASHI, Y., KOJIMA, T..  2020.  A Black Box Modeling Technique for Distortion Stomp Boxes Using LSTM Neural Networks. 2020 International Conference on Artificial Intelligence in Information and Communication (ICAIIC). :653–656.
This paper describes an experimental result of modeling stomp boxes of the distortion effect based on a machine learning approach. Our proposed technique models a distortion stomp box as a neural network consisting of LSTM layers. In this approach, the neural network is employed for learning the nonlinear behavior of the distortion stomp boxes. All the parameters for replicating the distortion sound are estimated through its training process using the input and output signals obtained from some commercial stomp boxes. The experimental result indicates that the proposed technique may have a certain appropriateness to replicate the distortion sound by using the well-trained neural networks.
2021-02-03
Gillen, R. E., Anderson, L. A., Craig, C., Johnson, J., Columbia, A., Anderson, R., Craig, A., Scott, S. L..  2020.  Design and Implementation of Full-Scale Industrial Control System Test Bed for Assessing Cyber-Security Defenses. 2020 IEEE 21st International Symposium on "A World of Wireless, Mobile and Multimedia Networks" (WoWMoM). :341—346.
In response to the increasing awareness of the Ethernet-based threat surface of industrial control systems (ICS), both the research and commercial communities are responding with ICS-specific security solutions. Unfortunately, many of the properties of ICS environments that contribute to the extent of this threat surface (e.g. age of devices, inability or unwillingness to patch, criticality of the system) similarly prevent the proper testing and evaluation of these security solutions. Production environments are often too fragile to introduce unvetted technology and most organizations lack test environments that are sufficiently consistent with production to yield actionable results. Cost and space requirements prevent the creation of mirrored physical environments leading many to look towards simulation or virtualization. Examples in literature provide various approaches to building ICS test beds, though most of these suffer from a lack of realism due to contrived scenarios, synthetic data and other compromises. In this paper, we provide a design methodology for building highly realistic ICS test beds for validating cybersecurity defenses. We then apply that methodology to the design and building of a specific test bed and describe the results and experimental use cases.
2020-12-11
Geng, J., Yu, B., Shen, C., Zhang, H., Liu, Z., Wan, P., Chen, Z..  2019.  Modeling Digital Low-Dropout Regulator with a Multiple Sampling Frequency Circuit Technology. 2019 IEEE 13th International Conference on Anti-counterfeiting, Security, and Identification (ASID). :207—210.

The digital low dropout regulators are widely used because it can operate at low supply voltage. In the digital low drop-out regulators, the high sampling frequency circuit has a short setup time, but it will produce overshoot, and then the output can be stabilized; although the low sampling frequency circuit output can be directly stabilized, the setup time is too long. This paper proposes a two sampling frequency circuit model, which aims to include the high and low sampling frequencies in the same circuit. By controlling the sampling frequency of the circuit under different conditions, this allows the circuit to combine the advantages of the circuit operating at different sampling frequencies. This shortens the circuit setup time and the stabilization time at the same time.

2020-11-09
Islam, S. A., Sah, L. K., Katkoori, S..  2019.  DLockout: A Design Lockout Technique for Key Obfuscated RTL IP Designs. 2019 IEEE International Symposium on Smart Electronic Systems (iSES) (Formerly iNiS). :17–20.
Intellectual Property (IP) infringement including piracy and overproduction have emerged as significant threats in the semiconductor supply chain. Key-based obfuscation techniques (i.e., logic locking) are widely applied to secure legacy IP from such attacks. However, the fundamental question remains open whether an attacker is allowed an exponential amount of time to seek correct key or could it be useful to lock out the design in a non-destructive manner after several incorrect attempts. In this paper, we address this question with a robust design lockout technique. Specifically, we perform comparisons on obfuscation logic output that reflects the condition (correct or incorrect) of the applied key without changing the system behavior. The proposed approach, when combined with key obfuscation (logic locking) technique, increases the difficulty of reverse engineering key obfuscated RTL module. We provide security evaluation of DLockout against three common side-channel attacks followed by a quantitative assessment of the resilience. We conducted a set of experiments on four datapath intensive IPs and one crypto core for three different key lengths (32-, 64-, and 128-bit) under the typical design corner. On average, DLockout incurs negligible area, power, and delay overheads.
Zaman, M., Sengupta, A., Liu, D., Sinanoglu, O., Makris, Y., Rajendran, J. J. V..  2018.  Towards provably-secure performance locking. 2018 Design, Automation Test in Europe Conference Exhibition (DATE). :1592–1597.
Locking the functionality of an integrated circuit (IC) thwarts attacks such as intellectual property (IP) piracy, hardware Trojans, overbuilding, and counterfeiting. Although functional locking has been extensively investigated, locking the performance of an IC has been little explored. In this paper, we develop provably-secure performance locking, where only on applying the correct key the IC shows superior performance; for an incorrect key, the performance of the IC degrades significantly. This leads to a new business model, where the companies can design a single IC capable of different performances for different users. We develop mathematical definitions of security and theoretically, and experimentally prove the security against the state-of-the-art-attacks. We implemented performance locking on a FabScalar microprocessor, achieving a degradation in instructions per clock cycle (IPC) of up to 77% on applying an incorrect key, with an overhead of 0.6%, 0.2%, and 0% for area, power, and delay, respectively.
Saeed, S. M., Cui, X., Zulehner, A., Wille, R., Drechsler, R., Wu, K., Karri, R..  2018.  IC/IP Piracy Assessment of Reversible Logic. 2018 IEEE/ACM International Conference on Computer-Aided Design (ICCAD). :1–8.
Reversible logic is a building block for adiabatic and quantum computing in addition to other applications. Since common functions are non-reversible, one needs to embed them into proper-size reversible functions by adding ancillary inputs and garbage outputs. We explore the Intellectual Property (IP) piracy of reversible circuits. The number of embeddings of regular functions in a reversible function and the percent of leaked ancillary inputs measure the difficulty of recovering the embedded function. To illustrate the key concepts, we study reversible logic circuits designed using reversible logic synthesis tools based on Binary Decision Diagrams and Quantum Multi-valued Decision Diagrams.
2020-11-02
Qin, Maoyuan, Hu, Wei, Mu, Dejun, Tai, Yu.  2018.  Property Based Formal Security Verification for Hardware Trojan Detection. 2018 IEEE 3rd International Verification and Security Workshop (IVSW). :62—67.

The design of modern computer hardware heavily relies on third-party intellectual property (IP) cores, which may contain malicious hardware Trojans that could be exploited by an adversary to leak secret information or take control of the system. Existing hardware Trojan detection methods either require a golden reference design for comparison or extensive functional testing to identify suspicious signals. In this paper, we propose a new formal verification method to verify the security of hardware designs. The proposed solution formalizes fine grained gate level information flow model for proving security properties of hardware designs in the Coq theorem prover environment. Compare with existing register transfer level (RTL) information flow security models, our model only needs to translate a small number of logic primitives to their formal representations without the need of supporting the rich RTL HDL semantics or dealing with complex conditional branch or loop structures. As a result, a gate level information flow model can be created at much lower complexity while achieving significantly higher precision in modeling the security behavior of hardware designs. We use the AES-T1700 benchmark from Trust-HUB to demonstrate the effectiveness of our solution. Experimental results show that our method can detect and pinpoint the Trojan.

2020-09-18
Guo, Xiaolong, Dutta, Raj Gautam, He, Jiaji, Tehranipoor, Mark M., Jin, Yier.  2019.  QIF-Verilog: Quantitative Information-Flow based Hardware Description Languages for Pre-Silicon Security Assessment. 2019 IEEE International Symposium on Hardware Oriented Security and Trust (HOST). :91—100.
Hardware vulnerabilities are often due to design mistakes because the designer does not sufficiently consider potential security vulnerabilities at the design stage. As a result, various security solutions have been developed to protect ICs, among which the language-based hardware security verification serves as a promising solution. The verification process will be performed while compiling the HDL of the design. However, similar to other formal verification methods, the language-based approach also suffers from scalability issue. Furthermore, existing solutions either lead to hardware overhead or are not designed for vulnerable or malicious logic detection. To alleviate these challenges, we propose a new language based framework, QIF-Verilog, to evaluate the trustworthiness of a hardware system at register transfer level (RTL). This framework introduces a quantified information flow (QIF) model and extends Verilog type systems to provide more expressiveness in presenting security rules; QIF is capable of checking the security rules given by the hardware designer. Secrets are labeled by the new type and then parsed to data flow, to which a QIF model will be applied. To demonstrate our approach, we design a compiler for QIF-Verilog and perform vulnerability analysis on benchmarks from Trust-Hub and OpenCore. We show that Trojans or design faults that leak information from circuit outputs can be detected automatically, and that our method evaluates the security of the design correctly.
Hong, Junho, Nuqui, Reynaldo F., Kondabathini, Anil, Ishchenko, Dmitry, Martin, Aaron.  2019.  Cyber Attack Resilient Distance Protection and Circuit Breaker Control for Digital Substations. IEEE Transactions on Industrial Informatics. 15:4332—4341.
This paper proposes new concepts for detecting and mitigating cyber attacks on substation automation systems by domain-based cyber-physical security solutions. The proposed methods form the basis of a distributed security domain layer that enables protection devices to collaboratively defend against cyber attacks at substations. The methods utilize protection coordination principles to cross check protection setting changes and can run real-time power system analysis to evaluate the impact of the control commands. The transient fault signature (TFS)-based cross-correlation coefficient algorithm has been proposed to detect the false sampled values data injection attack. The proposed functions were verified in a hardware-in-the-loop (HIL) simulation using commercial relays and a real-time digital simulator (RTDS). Various types of cyber intrusions are tested using this test bed to evaluate the consequences and impacts of cyber attacks to power grid as well as to validate the performance of the proposed research-grade cyber attack mitigation functions.
2020-07-30
Shey, James, Karimi, Naghmeh, Robucci, Ryan, Patel, Chintan.  2018.  Design-Based Fingerprinting Using Side-Channel Power Analysis for Protection Against IC Piracy. 2018 IEEE Computer Society Annual Symposium on VLSI (ISVLSI). :614—619.

Intellectual property (IP) and integrated circuit (IC) piracy are of increasing concern to IP/IC providers because of the globalization of IC design flow and supply chains. Such globalization is driven by the cost associated with the design, fabrication, and testing of integrated circuits and allows avenues for piracy. To protect the designs against IC piracy, we propose a fingerprinting scheme based on side-channel power analysis and machine learning methods. The proposed method distinguishes the ICs which realize a modified netlist, yet same functionality. Our method doesn't imply any hardware overhead. We specifically focus on the ability to detect minimal design variations, as quantified by the number of logic gates changed. Accuracy of the proposed scheme is greater than 96 percent, and typically 99 percent in detecting one or more gate-level netlist changes. Additionally, the effect of temperature has been investigated as part of this work. Results depict 95.4 percent accuracy in detecting the exact number of gate changes when data and classifier use the same temperature, while training with different temperatures results in 33.6 percent accuracy. This shows the effectiveness of building temperature-dependent classifiers from simulations at known operating temperatures.

2020-07-27
Liu, Dongqi.  2018.  A Creditability-based Intrusion Tolerant Method for Protection Equipment in Transformer Substations. 2018 China International Conference on Electricity Distribution (CICED). :1489–1492.
With the development of the interconnection of all things(IoT), a large number of mobile terminal devices with multiple users access the distribution network, and gradually form an open and interconnected network environment, which brings new challenges to the security and protection of the distribution network. In this paper, a method of analyzing the sensing data of the digital substation is proposed, which can prevent the abnormal data from causing the malfunction of the protective relays by calculating the creditability of the sensing data. Creditability calculation algorithm as well as the implementation of the intrusion tolerance strategy are studied throughout the paper. The simulation results show that the proposed creditability-based intrusion-tolerant(CIT) algorithm can ensure that the protective equipment have no protective malfunction from the false instructions or false data attacks, and the proposed intrusion tolerant algorithm has little affect on the real-time performance of the original protection algorithm, hence it has some practical value.
2020-07-20
Komargodski, Ilan, Naor, Moni, Yogev, Eylon.  2017.  White-Box vs. Black-Box Complexity of Search Problems: Ramsey and Graph Property Testing. 2017 IEEE 58th Annual Symposium on Foundations of Computer Science (FOCS). :622–632.
Ramsey theory assures us that in any graph there is a clique or independent set of a certain size, roughly logarithmic in the graph size. But how difficult is it to find the clique or independent set? If the graph is given explicitly, then it is possible to do so while examining a linear number of edges. If the graph is given by a black-box, where to figure out whether a certain edge exists the box should be queried, then a large number of queries must be issued. But what if one is given a program or circuit for computing the existence of an edge? This problem was raised by Buss and Goldberg and Papadimitriou in the context of TFNP, search problems with a guaranteed solution. We examine the relationship between black-box complexity and white-box complexity for search problems with guaranteed solution such as the above Ramsey problem. We show that under the assumption that collision resistant hash function exist (which follows from the hardness of problems such as factoring, discrete-log and learning with errors) the white-box Ramsey problem is hard and this is true even if one is looking for a much smaller clique or independent set than the theorem guarantees. In general, one cannot hope to translate all black-box hardness for TFNP into white-box hardness: we show this by adapting results concerning the random oracle methodology and the impossibility of instantiating it. Another model we consider is the succinct black-box, where there is a known upper bound on the size of the black-box (but no limit on the computation time). In this case we show that for all TFNP problems there is an upper bound on the number of queries proportional to the description size of the box times the solution size. On the other hand, for promise problems this is not the case. Finally, we consider the complexity of graph property testing in the white-box model. We show a property which is hard to test even when one is given the program for computing the graph. The hard property is whether the graph is a two-source extractor.
2020-05-15
Biswas, Arnab Kumar.  2018.  Efficient Timing Channel Protection for Hybrid (Packet/Circuit-Switched) Network-on-Chip. IEEE Transactions on Parallel and Distributed Systems. 29:1044—1057.
Continuous development of Network-on-Chip (NoC) enables different types of applications to run efficiently in a Multiprocessor System-on-Chip (MP-SoC). Guaranteed service (GS) can be provided by circuit switching NoC and Best effort service (BES) can be provided by packet switching NoC. A hybrid NoC containing both packet and circuit switching, can provide both types of services to these different applications. But these different applications can be of different security levels and one application can interfere another application's timing characteristics during network transmission. Using this interference, a malicious application can extract secret information from higher security level flows (timing side channel) or two applications can communicate covertly violating the system's security policy (covert timing channel). We propose different mechanisms to protect hybrid routers from timing channel attacks. For design space exploration, we propose three timing channel secure hybrid routers viz. Separate Hybrid (SH), Combined with Separate interface Hybrid (CSH), and Combined Hybrid (CH) routers. Simulation results show that all three routers are secure from timing channel when compared to a conventional hybrid router. Synthesis results show that the area increments compared to a conventional hybrid router are only 7.63, 11.8, and 19.69 percent for SH, CSH, and CH routers respectively. Thus simulation and synthesis results prove the effectiveness of our proposed mechanisms with acceptable area overheads.
2020-04-24
Noeren, Jannis, Parspour, Nejila.  2019.  A Dynamic Model for Contactless Energy Transfer Systems. 2019 IEEE PELS Workshop on Emerging Technologies: Wireless Power Transfer (WoW). :297—301.

Inductive contactless energy transfer (CET) systems show a certain oscillating transient behavior of inrush currents on both system sides. This causes current overshoots in the electrical components and has to be considered for the system dimensioning. This paper presents a simple and yet very accurate model, which describes the dynamic behavior of series-series compensated inductive CET systems. This model precisely qualifies the systems current courses for both sides in time domain. Additionally, an analysis in frequency domain allows further knowledge for parameter estimation. Since this model is applicable for purely resistive loads and constant voltage loads with bridge rectifiers, it is very practicable and can be useful for control techniques and narameter estimation.

Balijabudda, Venkata Sreekanth, Thapar, Dhruv, Santikellur, Pranesh, Chakraborty, Rajat Subhra, Chakrabarti, Indrajit.  2019.  Design of a Chaotic Oscillator based Model Building Attack Resistant Arbiter PUF. 2019 Asian Hardware Oriented Security and Trust Symposium (AsianHOST). :1—6.

Physical Unclonable Functions (PUFs) are vulnerable to various modelling attacks. The chaotic behaviour of oscillating systems can be leveraged to improve their security against these attacks. We have integrated an Arbiter PUF implemented on a FPGA with Chua's oscillator circuit to obtain robust final responses. These responses are tested against conventional Machine Learning and Deep Learning attacks for verifying security of the design. It has been found that such a design is robust with prediction accuracy of nearly 50%. Moreover, the quality of the PUF architecture is evaluated for uniformity and uniqueness metrics and Monte Carlo analysis at varying temperatures is performed for determining reliability.

2020-03-23
Daoud, Luka, Rafla, Nader.  2019.  Analysis of Black Hole Router Attack in Network-on-Chip. 2019 IEEE 62nd International Midwest Symposium on Circuits and Systems (MWSCAS). :69–72.

Network-on-Chip (NoC) is the communication platform of the data among the processing cores in Multiprocessors System-on-Chip (MPSoC). NoC has become a target to security attacks and by outsourcing design, it can be infected with a malicious Hardware Trojan (HT) to degrades the system performance or leaves a back door for sensitive information leaking. In this paper, we proposed a HT model that applies a denial of service attack by deliberately discarding the data packets that are passing through the infected node creating a black hole in the NoC. It is known as Black Hole Router (BHR) attack. We studied the effect of the BHR attack on the NoC. The power and area overhead of the BHR are analyzed. We studied the effect of the locations of BHRs and their distribution in the network as well. The malicious nodes has very small area and power overhead, 1.98% and 0.74% respectively, with a very strong violent attack.

2020-03-16
Chau, Cuong, Hunt, Warren A., Kaufmann, Matt, Roncken, Marly, Sutherland, Ivan.  2019.  A Hierarchical Approach to Self-Timed Circuit Verification. 2019 25th IEEE International Symposium on Asynchronous Circuits and Systems (ASYNC). :105–113.
Self-timed circuits can be modeled in a link-joint style using a formally defined hardware description language. It has previously been shown how functional properties of these models can be formally verified with the ACL2 theorem prover using a scalable, hierarchical method. Here we extend that method to parameterized circuit families that may have loops and non-deterministic outputs. We illustrate this extension with iterative self-timed circuits that calculate the greatest common divisor of two natural numbers, with circuits that perform arbitrated merges non-deterministically, and with circuits that combine both of these.
Eneh, Joy Nnenna, Onyekachi Orah, Harris, Emeka, Aka Benneth.  2019.  Improving the Reliability and Security of Active Distribution Networks Using SCADA Systems. 2019 IEEE PES/IAS PowerAfrica. :110–115.
The traditional electricity distribution system is rapidly shifting from the passive infrastructure to a more active infrastructure, giving rise to a smart grid. In this project an active electricity distribution network and its components have been studied. A 14-node SCADA-based active distribution network model has been proposed for managing this emerging network infrastructure to ensure reliability and protection of the network The proposed model was developed using matlab /simulink software and the fuzzy logic toolbox. Surge arresters and circuit breakers were modelled and deployed in the network at different locations for protection and isolation of fault conditions. From the reliability analysis of the proposed model, the failure rate and outage hours were reduced due to better response of the system to power fluctuations and fault conditions.
2020-03-12
Shamsi, Kaveh, Pan, David Z., Jin, Yier.  2019.  On the Impossibility of Approximation-Resilient Circuit Locking. 2019 IEEE International Symposium on Hardware Oriented Security and Trust (HOST). :161–170.

Logic locking, and Integrated Circuit (IC) Camouflaging, are techniques that try to hide the design of an IC from a malicious foundry or end-user by introducing ambiguity into the netlist of the circuit. While over the past decade an array of such techniques have been proposed, their security has been constantly challenged by algorithmic attacks. This may in part be due to a lack of formally defined notions of security in the first place, and hence a lack of security guarantees based on long-standing hardness assumptions. In this paper we take a formal approach. We define the problem of circuit locking (cL) as transforming an original circuit to a locked one which is ``unintelligable'' without a secret key (this can model camouflaging and split-manufacturing in addition to logic locking). We define several notions of security for cL under different adversary models. Using long standing results from computational learning theory we show the impossibility of exponentially approximation-resilient locking in the presence of an oracle for large classes of Boolean circuits. We then show how exact-recovery-resiliency and a more relaxed notion of security that we coin ``best-possible'' approximation-resiliency can be provably guaranteed with polynomial overhead. Our theoretical analysis directly results in stronger attacks and defenses which we demonstrate through experimental results on benchmark circuits.