Design Methods for Cryptanalysis

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Virginia Tech

Security of cryptographic algorithms relies on the computational difficulty of deriving the secret key using public information. Cryptanalysis, including logical and implementation attacks, plays an important role in allowing the security community to estimate their cost, based on the computational resources of an attacker. Practical implementations of cryptanalytic systems require complex designs that integrate multiple functional components with many parameters.

In this thesis, methodologies are proposed to improve the design process of cryptanalytic systems and reduce the cost of design space exploration required for optimization.

First, Bluespec, a rule-based HDL, is used to increase the abstraction level of hardware design and support efficient design space exploration. Bluespec is applied to implement a hardware-accelerated logical attack on ECC with optimized modular arithmetic components. The language features of Bluespec support exploration and this is demonstrated by applying Bluespec to investigate the speed area tradeoff resulting from various design parameters and demonstrating performance that is competitive with prior work. This work also proposes a testing environment for use in verifying the implementation attack resistance of secure systems. A modular design approach is used to provide separation between the device being tested and the test script, as well as portability, and openness. This yields an open-source solution that supports implementation attack testing independent of the system platform, implementation details, and type of attack under evaluation. The suitability of the proposed test environment for implementation attack vulnerability analysis is demonstrated by applying the environment to perform an implementation attack on AES.

The design of complex cryptanalytic hardware can greatly benefit from better design methodologies and the results presented in this thesis advocate the importance of this aspect.

Implementation attack, Design method, Bluespec, Prime field arithmetic, Pollard rho, Elliptic curve cryptography (ECC), Field programmable gate arrays, Hardware software co-design, Fault attack, Side-channel analysis (SCA)