Paper 2021/722
Chosen Ciphertext Secure Keyed Two-Level Homomorphic Encryption
Yusaku Maeda and Koji Nuida
Abstract
Homomorphic encryption (HE) is a useful variant of public key encryption (PKE), but it has a drawback that HE cannot fully achieve IND-CCA2 security, which is a standard security notion for PKE. Beyond existing HE schemes achieving weaker IND-CCA1 security, Emura et al.\ (PKC 2013) proposed the notion of \lq\lq keyed\rq\rq{} version of HE, called KH-PKE, which introduces an evaluation key controlling the functionality of homomorphic operations and achieves security stronger than IND-CCA1 and as close to IND-CCA2 as possible. After Emura et al.'s scheme which can evaluate linear polynomials only, Lai et al.\ (PKC 2016) proposed a fully homomorphic KH-PKE, but it requires indistinguishability obfuscation and hence has a drawback in practical feasibility. In this paper, we propose a \lq\lq two-level\rq\rq{} KH-PKE scheme for evaluating degree-two polynomials, by cleverly combining Emura et al.'s generic framework with a recent efficient two-level HE by Attrapadung et al.\ (ASIACCS 2018). Our scheme is the first KH-PKE that can handle non-linear polynomials while keeping practical efficiency.
Metadata
- Available format(s)
- Category
- Public-key cryptography
- Publication info
- Preprint. MINOR revision.
- Keywords
- public key encryptionkeyed homomorphic encryptionhash proof system
- Contact author(s)
- yusaku maeda1996 @ gmail com,nuida @ imi kyushu-u ac jp
- History
- 2022-12-18: revised
- 2021-05-31: received
- See all versions
- Short URL
- https://ia.cr/2021/722
- License
-
CC BY