Cryptology ePrint Archive: Report 2022/447

Leveled Multikey FHE with constant-size ciphertexts from RLWE

Vanesa Daza and Paz Morillo and Sergi Rovira

Abstract: A multi-key fully homomorphic encryption (MKFHE) scheme allows a public server to evaluate arbitrary circuits over ciphertexts encrypted under different keys. One of the main drawbacks of MKFHE schemes is the need for a ciphertext expansion procedure prior to evaluation, which combines ciphertexts encrypted under different keys to a (much larger) ciphertext encrypted under a concatenated key. In this paper, we present a new (leveled) RLWE-based MKFHE scheme without ciphertext expansion.

Category / Keywords: public-key cryptography / Multi-key fully homomorphic encryption, Ring learning with errors, Party- independent ciphertexts

Date: received 8 Apr 2022

Contact author: sergi rovira at upf edu, vanesa daza at upf edu, paz morillo at upc edu

Available format(s): PDF | BibTeX Citation

Version: 20220412:074359 (All versions of this report)

Short URL: ia.cr/2022/447


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