Transactions on Cryptographic Hardware and Embedded Systems (Aug 2022)

SoK: Fully Homomorphic Encryption over the [Discretized] Torus

  • Marc Joye

Journal volume & issue
Vol. 2022, no. 4

Abstract

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First posed as a challenge in 1978 by Rivest et al., fully homomorphic encryption—the ability to evaluate any function over encrypted data—was only solved in 2009 in a breakthrough result by Gentry (Commun. ACM, 2010). After a decade of intense research, practical solutions have emerged and are being pushed for standardization. This paper explains the inner-workings of TFHE, a torus-based fully homomorphic encryption scheme. More exactly, it describes its implementation on a discretized version of the torus. It also explains in detail the technique of the programmable bootstrapping. Numerous examples are provided to illustrate the various concepts and definitions.

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