Cryptology ePrint Archive: Report 2021/1402

Guide to Fully Homomorphic Encryption over the [Discretized] Torus

Marc Joye

Abstract: 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. After a decade of intense research, practical solutions have emerged and are being pushed for standardization.

This guide is intended to practitioners. It 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.

Category / Keywords: implementation / FHE, TFHE, LWE, Discretized torus, Programmable bootstrapping

Date: received 17 Oct 2021, last revised 17 Oct 2021

Contact author: marc at zama ai

Available format(s): PDF | BibTeX Citation

Version: 20211018:061637 (All versions of this report)

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