Efficient Homomorphic Encryption with Key Rotation and Security Update

Yoshinori AONO  Takuya HAYASHI  Le Trieu PHONG  Lihua WANG  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E101-A   No.1   pp.39-50
Publication Date: 2018/01/01
Online ISSN: 1745-1337
Type of Manuscript: Special Section PAPER (Special Section on Cryptography and Information Security)
homomorphic encryption,  Learning With Errors,  key rotation,  security update,  

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We present the concept of key-rotatable and security-updatable homomorphic encryption (KR-SU-HE) scheme, which is defined as a class of public-key homomorphic encryption in which the keys and the security of any ciphertext can be rotated and updated while still keeping the underlying plaintext intact and unrevealed. After formalising the syntax and security notions for KR-SU-HE schemes, we build a concrete scheme based on the Learning With Errors assumption. We then perform several careful implementations and optimizations to show that our proposed scheme is efficiently practical.