Development of advanced digital techniques for data acquisition processing and communication Interim scientific report

Design, video data characteristics, error control, and compression algorithms for Mars television mapping missio

SRAM PUF의 신뢰성 개선을 위한 전원 공급 기법

학위논문 (석사) -- 서울대학교 대학원 : 융합과학기술대학원 융합과학부(지능형융합시스템전공), 2021. 2. 전동석.PUF (Physically Unclonable Function)은 하드웨어 레벨의 인증 과 정에서 널리 이용되는 방법이다. 그 중에서도 SRAM PUF는 가장 잘 알 려진 PUF의 방법론이다. 그러나 예측 불가능한 동작으로 인해 발생되는 낮은 재생산성과 전원 공급 과정에서 발생하는 노이즈의 문제를 가지고 있다. 본 논문에서는 효과적으로 SRAM PUF의 재생산성을 향상시킬 수 있는 두 가지 전원 공급 기법을 제안한다. 제시한 기법들은 값이 산출되 는 영역 혹은 전원 공급원의 기울기(ramp-up 시간)를 조절함으로써 원 하지 않는 비트의 뒤집힘(flipping) 현상을 줄인다. 180nm 공정으로 제 작된 테스트 칩을 이용한 측정 결과 재생산성이 2.2배 향상되었을 뿐만 아니라 NUBs(Native Unstable Bits)는 54.87% 그리고 BER (Bit Error Rate)는 55.05% 감소한 것을 확인하였다.Physically unclonable function (PUF) is a widely used hardware-level identification method. SRAM-based PUFs are the most well-known PUF topology, but they typically suffer from low reproducibility due to non-deterministic behaviors and noise during power-up process. In this work, we propose two power-up control techniques that effectively improve reproducibility of the SRAM PUFs. The techniques reduce undesirable bit flipping during evaluation by controlling either evaluation region or power supply ramp-up speed. Measurement results from the 180 nm test chip confirm that native unstable bits (NUBs) are reduced by 54.87% and bit error rate (BER) decreases by 55.05% while reproducibility increases by 2.2×.Chapter 1 Introduction 1 1.1 PUF in Hardware Securit 1 1.2 Prior Works and Motivation 2 Chapter 2 Related works and Motivation 5 2.1 Uniqueness 7 2.2 Reproducibility 7 2.3 Hold Static Noise Margin (SNM) 8 2.4 Bit Error Rate (BER) 9 2.5 PUF Static Noise Margin Ratio (PSNMratio) 9 Chapter 3 Microarchitecture-Aware Code Generation 11 3.1 Scheme 1: Developing Fingerprint in Sub-Threshold Region 13 3.2 Scheme 2: Controlling Voltage Ramp-up Speed 17 Chapter 4 Experimental Evaluation 19 4.1 Experimental Setup 19 4.2 Evaluation Results 21 Chapter 5 Conclusion 28 Bibliography 29 Abstract in Korean 33Maste

Threat Analysis, Countermeaures and Design Strategies for Secure Computation in Nanometer CMOS Regime

Advancements in CMOS technologies have led to an era of Internet Of Things (IOT), where the devices have the ability to communicate with each other apart from their computational power. As more and more sensitive data is processed by embedded devices, the trend towards lightweight and efficient cryptographic primitives has gained significant momentum. Achieving a perfect security in silicon is extremely difficult, as the traditional cryptographic implementations are vulnerable to various active and passive attacks. There is also a threat in the form of hardware Trojans inserted into the supply chain by the untrusted third-party manufacturers for economic incentives. Apart from the threats in various forms, some of the embedded security applications such as random number generators (RNGs) suffer from the impacts of process variations and noise in nanometer CMOS. Despite their disadvantages, the random and unique nature of process variations can be exploited for generating unique identifiers and can be of tremendous use in embedded security. In this dissertation, we explore techniques for precise fault-injection in cryptographic hardware based on voltage/temperature manipulation and hardware Trojan insertion. We demonstrate the effectiveness of these techniques by mounting fault attacks on state-of-the-art ciphers. Physically Unclonable Functions (PUFs) are novel cryptographic primitives for extracting secret keys from complex manufacturing variations in integrated circuits (ICs). We explore the vulnerabilities of some of the popular strong PUF architectures to modeling attacks using Machine Learning (ML) algorithms. The attacks use silicon data from a test chip manufactured in IBM 32nm silicon-on-insulator (SOI) technology. Attack results demonstrate that the majority of strong PUF architectures can be predicted to very high accuracies using limited training data. We also explore the techniques to exploit unreliable data from strong PUF architectures and effectively use them to improve the prediction accuracies of modeling attacks. Motivated by the vulnerabilities of existing PUF architectures, we present a novel modeling attack resistant PUF architecture based on non-linear computing elements. Post-silicon validation results are used to demonstrate the effectiveness of the non-linear PUF architecture against modeling and fault-injection attacks. Apart from the techniques to improve the security of PUF circuits, we also present novel solutions to improve the performance of PUF circuits from the perspectives of IC fabrication and system/protocol design. Finally, we present a statistical benchmark suite to evaluate PUFs in conceptualization phase and also to enable fine-grained security assessments for varying PUF parameters. Data compressibility analyses for validating the statistical benchmark suite are also presented

物理複製不能関数における安全性の評価と向上に関する研究

In this thesis, we focus on Physically Unclonable Functions (PUFs), which are expected as one of the most promising cryptographic primitives for secure chip authentication. Generally, PUFbased authentication is achieved by two approaches: (A) using a PUF itself, which has multiple challenge (input) and response (output) pairs, or (B) using a cryptographic function, the secret key of which is generated from a PUF with a single challenge-response pair (CRP). We contribute to:(1) evaluate the security of Approach (A), and (2) improve the security of Approach (B). (1) Arbiter-based PUFs were the most feasible type of PUFs, which was used to construct Approach (A). However, Arbiter-based PUFs have a vulnerability; if an attacker knows some CRPs, she/he can predict the remaining unknown CRPs with high probability. Bistable Ring PUF (BR-PUF) was proposed as an alternative, but has not been evaluated by third parties. In this thesis, in order to construct Approach (A) securely, we evaluate the difficulty of predicting responses of a BR-PUF experimentally. As a result, the same responses are frequently generated for two challenges with small Hamming distance. Also, particular bits of challenges have a great impact on the responses. In conclusion, BR-PUFs are not suitable for achieving Approach (A)securely. In future work, we should discuss an alternative PUF suitable for secure Approach (A).(2) In order to achieve Approach (B) securely, a secret key ? generated from a PUF response?should have high entropy. We propose a novel method of extracting high entropy from PUF responses. The core idea is to effectively utilize the information on the proportion of ‘1’s including in repeatedly-measured PUF responses. We evaluate its effectiveness by fabricated test chips. As a result, the extracted entropy is about 1.72 times as large as that without the proposed method.Finally, we organize newly gained knowledge in this thesis, and discuss a new application of PUF-based technologies.電気通信大学201

Design and Evaluation of FPGA-based Hybrid Physically Unclonable Functions

A Physically Unclonable Function (PUF) is a new and promising approach to provide security for physical systems and to address the problems associated with traditional approaches. One of the most important performance metrics of a PUF is the randomness of its generated response, which is presented via uniqueness, uniformity, and bit-aliasing. In this study, we implement three known PUF schemes on an FPGA platform, namely SR Latch PUF, Basic RO PUF, and Anderson PUF. We then perform a thorough statistical analysis on their performance. In addition, we propose the idea of the Hybrid PUF structure in which two (or more) sources of randomness are combined in a way to improve randomness. We investigate two methods in combining the sources of randomness and we show that the second one improves the randomness of the response, significantly. For example, in the case of combining the Basic RO PUF and the Anderson PUF, the Hybrid PUF uniqueness is increased nearly 8%, without any pre-processing or post-processing tasks required. Two main categories of applications for PUFs have been introduced and analyzed: authentication and secret key generation. In this study, we introduce another important application for PUFs. In fact, we develop a secret sharing scheme using a PUF to increase the information rate and provide cheater detection capability for the system. We show that, using the proposed method, the information rate of the secret sharing scheme will improve significantly

Design of Discrete-time Chaos-Based Systems for Hardware Security Applications

Security of systems has become a major concern with the advent of technology. Researchers are proposing new security solutions every day in order to meet the area, power and performance specifications of the systems. The additional circuit required for security purposes can consume significant area and power. This work proposes a solution which utilizes discrete-time chaos-based logic gates to build a system which addresses multiple hardware security issues. The nonlinear dynamics of chaotic maps is leveraged to build a system that mitigates IC counterfeiting, IP piracy, overbuilding, disables hardware Trojan insertion and enables authentication of connecting devices (such as IoT and mobile). Chaos-based systems are also used to generate pseudo-random numbers for cryptographic applications.The chaotic map is the building block for the design of discrete-time chaos-based oscillator. The analog output of the oscillator is converted to digital value using a comparator in order to build logic gates. The logic gate is reconfigurable since different parameters in the circuit topology can be altered to implement multiple Boolean functions using the same system. The tuning parameters are control input, bifurcation parameter, iteration number and threshold voltage of the comparator. The proposed system is a hybrid between standard CMOS logic gates and reconfigurable chaos-based logic gates where original gates are replaced by chaos-based gates. The system works in two modes: logic locking and authentication. In logic locking mode, the goal is to ensure that the system achieves logic obfuscation in order to mitigate IC counterfeiting. The secret key for logic locking is made up of the tuning parameters of the chaotic oscillator. Each gate has 10-bit key which ensures that the key space is large which exponentially increases the computational complexity of any attack. In authentication mode, the aim of the system is to provide authentication of devices so that adversaries cannot connect to devices to learn confidential information. Chaos-based computing system is susceptible to process variation which can be leveraged to build a chaos-based PUF. The proposed system demonstrates near ideal PUF characteristics which means systems with large number of primary outputs can be used for authenticating devices