Cryptology ePrint Archive: Report 2021/1624

On the IND-CCA1 Security of FHE Schemes

Prastudy Fauzi and Martha Norberg Hovd and Håvard Raddum

Abstract: Fully homomorphic encryption (FHE) is a powerful tool in cryptography that allows one to perform arbitrary computations on encrypted material without having to decrypt it first. There are numerous FHE schemes, all of which are expanded from somewhat homomorphic encryption (SHE) schemes, and some of which are considered viable in practice. However, while these FHE schemes are semantically (IND-CPA) secure, the question of their IND-CCA1 security is much less studied. In this paper, we group SHE schemes into broad categories based on their similarities and underlying hardness problems. For each category, we show that the SHE schemes are susceptible to either known adaptive key recovery attacks, a natural extension of known attacks, or our proposed attacks. Finally, we discuss the known techniques to achieve IND-CCA1 secure FHE and SHE schemes.

Category / Keywords: FHE schemes, IND-CCA, cryptanalysis

Date: received 13 Dec 2021

Contact author: prastudy fauzi at gmail com, martha at simula no, haavardr at simula no

Available format(s): PDF | BibTeX Citation

Version: 20211217:141822 (All versions of this report)

Short URL: ia.cr/2021/1624


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