| Summary: | 碩士 === 國立成功大學 === 電機工程學系 === 105 === Fully homomorphic encryption (FHE) is an emerging technique that allows the encrypted data to be processed directly in untrusted servers for ensuring data privacy. Despite of the important feature of FHE in cloud computing applications, there are still extremely high computation complexity and implementation cost in the underlying algorithms. Homomorphic evaluation of advanced encryption standard (AES) can be regarded as a complex function, in which existing homomorphic AES implementations still demand a significant amount of computational time. The most expensive operation in homomorphic AES is key switching after homomorphic multiplication and automorphism operations.
To improve the performance of homomorphic AES by reducing homomorphic multiplication and automorphism operations in critical computational paths, this thesis proposes a parallel SubByte and MixColumn/ShiftRow algorithm by relaxing the underlying data dependency. Compared to the conventional homomorphic AES, the proposed one can reduce 3 key switching operations in one round of homomorphic AES assuming parallel processing. Moreover, high-performance hardware architectures of homomorphic AES are presented for different security levels. Performance evaluations show that the proposed design outperforms the related works in terms of computational time and performance.
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