Paper 2024/1166
On the Relationship between FuncCPA and FuncCPA+
Abstract
Akavia, Gentry, Halevi, and Vald introduced the security notion of function-chosen-plaintext-attack (FuncCPA security) for public-key encryption schemes. FuncCPA is defined by adding a functional re-encryption oracle to the IND-CPA game. This notion is crucial for secure computation applications where the server is allowed to delegate a part of the computation to the client. Dodis, Halevi, and Wichs introduced a stronger variant called FuncCPA$^+$. They showed FuncCPA$^+$ implies FuncCPA and conjectured that FuncCPA$^+$ is strictly stronger than FuncCPA. They left an open problem to clarify the relationship between these variants. Contrary to their conjecture, we show that FuncCPA is equivalent to FuncCPA$^+$. We show it by two proofs with a trade-off between the number of queries and the number of function inputs. Furthermore, we show these parameters determine the security levels of FuncCPA and FuncCPA$^+$.
Metadata
- Available format(s)
-
PDF
- Category
- Public-key cryptography
- Publication info
- Preprint.
- Keywords
- FuncCPApublic-key encryption
- Contact author(s)
-
shinozaki t ae @ m titech ac jp
keisuke @ is titech ac jp
tezuka m ac @ m titech ac jp
yoshida yusuke @ c titech ac jp - History
- 2024-07-19: approved
- 2024-07-19: received
- See all versions
- Short URL
- https://ia.cr/2024/1166
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2024/1166,
author = {Takumi Shinozaki and Keisuke Tanaka and Masayuki Tezuka and Yusuke Yoshida},
title = {On the Relationship between {FuncCPA} and {FuncCPA}+},
howpublished = {Cryptology ePrint Archive, Paper 2024/1166},
year = {2024},
note = {\url{https://eprint.iacr.org/2024/1166}},
url = {https://eprint.iacr.org/2024/1166}
}
