Authors:
Jinyong Chang
1
and
Rui Xue
2
Affiliations:
1
Chinese Academy of Sciences and Changzhi University, China
;
2
Chinese Academy of Sciences, China
Keyword(s):
Key-dependent Message Security, CCA Security, DDH Assumption, Public Key Encryption.
Related
Ontology
Subjects/Areas/Topics:
Applied Cryptography
;
Cryptographic Techniques and Key Management
;
Data and Application Security and Privacy
;
Data Engineering
;
Databases and Data Security
;
Information and Systems Security
;
Privacy
;
Security in Information Systems
;
Security Requirements
Abstract:
An encryption scheme is key-dependent message chosen plaintext attack (KDM-CPA) secure means that it is secure even if an adversary obtains encryptions of messages that depend on the secret key. However, there are not many schemes that are KDM-CPA secure, let alone key-dependent message chosen ciphertext attack (KDM-CCA) secure. So far, only two general constructions, due to Camenisch, Chandran, and Shoup (Eurocrypt 2009), and Hofheinz (Eurocrypt 2013), are known to be KDM-CCA secure in the stand model. Another scheme, a concrete implementation, was recently proposed by Qin, Liu and Huang (ACISP 2013), where a KDM-CCA secure scheme was obtained from the classic Cramer-Shoup (CS) cryptosystem w.r.t. a new family of functions. In this paper, we revisit the KDM-CCA security of the CS-scheme and prove that, in two-user case, the CS-scheme achieves KDM-CCA security w.r.t. richer ensembles, which covers the result of Qin et al.. In addition, we present another proof about the result in (QL
H13) by extending our approach used in two-user case to n-user case, which achieves a tighter reduction to the decisional Diffie-Hellman (DDH) assumption.
(More)