Paper 2021/1431
Secure and Efficient Multi-Key FHE Scheme Supporting Multi-bit Messages from LWE Preserving Non-Interactive Decryption
Chinmoy Biswas and Ratna Dutta
Abstract
We consider multi-key fully homomorphic encryption (multi-key FHE) which is the richest variant of fully homomorphic encryption (FHE) that allows complex computation on encrypted data under different keys. Since its introduction by Lopez-Alt, Tromer and Vaikuntanathan in 2012, numerous proposals have been presented yielding various improvements in security and efficiency. However, most of these multi-key FHE schemes encrypt a single-bit message. Constructing a multi-key FHE scheme encrypting multi-bit messages have been notoriously difficult without loosing efficiency for homomorphic evaluation and ciphertext extension under additional keys. In this work, we study multi-key FHE that can encrypt multi-bit messages. Motivated by the goals of improving the efficiency, we propose a new construction with non-interactive decryption and security against chosen-plaintext attack (IND-CPA) from the standard learning with errors (LWE) assumption. We consider a binary matrix as plaintext instead of a single-bit. Our approach supports efficient homomorphic matrix addition and multiplication. Another interesting feature is that our technique of extending a ciphertext under additional keys yields significant reduction in the computational overhead. More interestingly, when contrasted with the previous multi-key FHE schemes for multi-bit messages, our candidates exhibits favorable results in the length of the secret key, public key and ciphertext preserving non-interactive decryption. Keywords: lattice based cryptosystem, multi-key fully homomorphic encryption, learning with errors, multi-bit messages
Metadata
- Available format(s)
- Category
- Public-key cryptography
- Publication info
- Preprint. MINOR revision.
- Keywords
- lattice techniquespublic-key cryptography
- Contact author(s)
- chinmoy88biswas @ gmail com
- History
- 2021-10-26: received
- Short URL
- https://ia.cr/2021/1431
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2021/1431, author = {Chinmoy Biswas and Ratna Dutta}, title = {Secure and Efficient Multi-Key {FHE} Scheme Supporting Multi-bit Messages from {LWE} Preserving Non-Interactive Decryption}, howpublished = {Cryptology {ePrint} Archive, Paper 2021/1431}, year = {2021}, url = {https://eprint.iacr.org/2021/1431} }