CY-801 Hardware Security - May 2024 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aDefine hardware security. Explain the significance of hardware security in detail.
   How to answer

   • Definition of hardware security as protection of physical devices, ICs and supply chain
   • Threats: counterfeiting, tampering, side-channel, fault injection, piracy
   • Significance for trust, IP protection, secure boot and critical infrastructure
   • Relation to software and system-level security
2. 7 Marks
   bWhat is a finite field? Show that for any element $m \in F$, $m * 0 = 0$.
   How to answer

   • Definition of finite field: finite set with addition and multiplication satisfying field axioms
   • Recall field axioms: additive and multiplicative identity, inverses, distributivity
   • Proof using $m*0 = m*(0+0) = m*0 + m*0$ and cancellation
   • Conclude $m*0 = 0$ for all $m \in F$
3. 7 Marks
   aConstruct a finite field with $2^2 = 4$ elements using the prime degree - 2 polynomial $f(x) = x^2 + x + 1 \in F2[x]$.
   How to answer

   • State $F2 = \{0,1\}$ and irreducible $f(x)=x^2+x+1 \in F2[x]$
   • Construct quotient ring $F2[x]/(f)$ with 4 elements $0,1,x,x+1$
   • Show addition and multiplication tables modulo $f(x)$
   • Verify field properties and list inverses
4. 7 Marks
   bExplain about accuracy issues and precision enhancement in FGPA.
   How to answer

   • Define accuracy and precision issues in FPGA implementations
   • Sources: quantization, fixed-point truncation, routing delay
   • Precision enhancement techniques: word-length optimization, pipelining
   • Impact on cryptographic and signal processing accuracy
5. 7 Marks
   aDiscuss with different types of PUF attacks with examples.
   How to answer

   • Define PUF and attack goals: cloning, modeling, reliability attacks
   • Types: machine-learning modeling, side-channel, fault, replay, man-in-the-middle
   • Give example for each type e.g., arbiter PUF modeling
   • Countermeasures overview
6. 7 Marks
   bExplain about design techniques to increase PUF response quality.
   How to answer

   • Define PUF response quality metrics: uniqueness, reliability, uniformity
   • Design techniques: error correction, fuzzy extractors, selection
   • Circuit techniques: symmetric layout, aging compensation
   • Challenge-response enhancement methods
7. 7 Marks
   aWhat is side-channel attacks? Explain different types of side channel attacks.
   How to answer

   • Define side-channel attacks exploiting physical leakage
   • Types: timing, power analysis, electromagnetic, acoustic, cache
   • Explain passive vs active and simple vs differential
   • Example scenario for each type
8. 7 Marks
   bWhat are the counter measures for preventing side-channel attacks? Explain in detail.
   How to answer

   • List countermeasure classes: hiding, masking, shielding
   • Explain noise addition, power balancing, constant-time design
   • Describe masking and secret sharing
   • Discuss physical and architectural protections
9. 7 Marks
   aExplain about improved side-channel attack by using DES algorithm.
   How to answer

   • Brief DES structure and leakage points
   • How power/timing traces reveal S-box operations
   • Improved attack flow: trace collection, alignment, differential analysis
   • Result: key recovery with fewer traces
10. 7 Marks
    bExplain the architecture of fault tolerance of cryptography with a neat sketch.
    How to answer

    • Define fault tolerance in cryptographic hardware
    • Block diagram: redundant modules, voter, error detection
    • Explain TMR, parity and concurrent error detection
    • Neat labeled sketch of fault-tolerant architecture
11. 7 Marks
    aDevelop a domain-specific implementation for finite field multipliers.
    How to answer

    • Need for efficient finite field multipliers in crypto hardware
    • Domain-specific choices: polynomial vs normal basis
    • Implementation steps: reduction, Karatsuba, pipelining
    • Area-time trade-offs and example GF(2^m) multiplier
12. 7 Marks
    bGiven an arithmetic circuit C with input variables $a_1, a_2, \dots, a_n$ and constants taken from a field F, Check if the polynomial computed is identically zero.
    How to answer

    • Define arithmetic circuit $C$ over field $F$ with inputs $a_1,...,a_n$
    • Problem: polynomial identity testing whether computed polynomial $\equiv 0$
    • Randomized Schwartz-Zippel lemma based test
    • Steps and error probability analysis
13. 7 Marks
    aDescribe about various procedures involved to prevent hardware piracy using PUFs.
    How to answer

    • Define hardware piracy: overbuilding, cloning, counterfeiting
    • PUF-based authentication and key generation flow
    • Procedures: enrollment, challenge-response, secure binding
    • Anti-piracy protocol and supply-chain integration
14. 7 Marks
    bDiscuss with model building attacks on PUFs with suitable examples.
    How to answer

    • Define model building attacks using ML on CRPs
    • Examples: logistic regression, SVM on arbiter PUF
    • Factors: number of CRPs, prediction accuracy
    • Defenses: controlled PUFs, XOR PUFs
15. 14 Marks
    Write a short note on any two of the following:

    1. a)Field-Programmable Gate Array (FPGA)
    2. b)Security Parameters of PUF
    3. c)Cache Attacks
    4. d)Fault Attacks
    How to answer

    • Lead-in on choice of any two topics for full marks
    • For each chosen topic: definition, key features and working
    • Relevant attacks/parameters/architecture diagram
    • Applications in hardware security with example