Backward-Leak Uni-Directional Updatable Encryption from (Homomorphic) Public Key Encryption
Peer reviewed, Journal article
Accepted version
Permanent lenke
https://hdl.handle.net/11250/3084334Utgivelsesdato
2023Metadata
Vis full innførselSamlinger
Originalversjon
https://doi.org/10.1007/978-3-031-31371-4_14Sammendrag
The understanding of directionality for updatable encryption (UE) schemes is important, but not yet completed in the literature. We show that security in the backward-leak uni-directional key updates setting is equivalent to the no-directional one. Combining with the work of Jiang (ASIACRYPT 2020) and Nishimaki (PKC 2022), it is showed that the backward-leak notion is the strongest one among all known key update notions and more relevant in practice. We propose two novel generic constructions of UE schemes that are secure in the backward-leak uni-directional key update setting from public key encryption (PKE) schemes: the first one requires a key and message homomorphic PKE scheme and the second one requires a bootstrappable PKE scheme. These PKE can be constructed based on standard assumptions (such as the Decisional Diffie-Hellman and Learning With Errors assumptions).