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Re-imagining the Security of the Hardware using Lookup Table based Obfuscation


The increasing cost of manufacturing the complex Integrated Circuits (ICs) and ever-rising competition to shorten time-to-market have given rise to the trend of fabless manufacturing. Moreover, the addition of various players in the product manufacturing lifecycle has endangered the security of Intellectual Property (IP). “Logic locking” and “IC camouflaging” are amongst the most prevalent protection schemes that can thwart various hardware security threats. However, the state-of-the-art attacks such as Boolean Satisfiability Attack (SAT-attack) and approximation-based attacks, question the efficacy of the existing defense schemes.

Recent solutions to protect hardware designs from various hardware security threats have employed a myriad of obfuscation techniques. However, these solutions have mostly focused on specific design elements such as “SAT-hardness”. Despite meeting the focused criterion such as “SAT-hardness” for maximizing security, obfuscated designs are still vulnerable to the newly evolving attack vectors. To mitigate this problem and provide a better solution that can thwart SAT-attackand provide better resilience against evolving attack vectors, Look-Up Table (LUT)-based obfuscation is studied. This work provides an extensive analysis of LUT-based obfuscation by exploring several factors such as LUT technology, size, number of LUTs, and replacement strategy as they have a substantial influence on the Power-Performance-Area (PPA) and security of the design.

For making the reconfigurable logic obfuscation efficient in terms of design overheads, this work further proposes a novel architecture using LUT. Additionally, a study is conducted with different threat models and attack vectors to show that the security provided by the proposed primitive is superior to that of the traditional ways of LUT-based obfuscation.

While many existing works have focused on mitigating the well-known SAT attack and its derivatives, there hasn’t been much research on preventing Power Side-Channel Attacks (PSCAs), which have the capability to retrieve the sensitive contents of the IP in a non-invasive manner. Using P-SCA for unlocking the obfuscated circuit, does not require the laborious task of simulating powerful SAT attacks. For maximizing the security, and curbing P-SCA, the work proposes a “defense-in-depth obfuscation” which builds on our existing LUT-based solution. The proposed obfuscation is tailored such that LUT-based obfuscation incurs minimal overheads while providing a full-scale robust solution to secure the hardware.

Additionally, this work invents a security-driven design flow, which uses off-the-shelf industrial Electronic Design Automation (EDA) tools for easier obfuscation of the design. This proposed flow is meticulously crafted in a way such that it is non-disruptive to the current industrial physical design flow. To enable this flow one must overcome some obstacles; as there is a lack of frameworks and unified methods that can validate the security and functionality of obfuscated designs This work has discussed the challenges of validating the security and functionality of obfuscated designs and further presents the methodology of verifying the functionality for the LUT-based obfuscated IP (pre and post-fabrication). Additionally, Security Evaluation Platform for Hardware Logic Obfuscation using Intelligent Artificial Neural Net (SEPIANN) is proposed to validate the security of the design. This system-level framework instantaneously estimates the obfuscation strength in terms of attack resiliency time eliminating the need to simulate de-obfuscation using the SAT attack.

Finally, the work shows the application and scalability of the proposed work by fabricating various security and computing cores by obfuscating them with the LUT-based obfuscation.

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