Revocable identity-based encryption with bounded decryption key exposure resistance: Lattice-based construction and more.

摘要

In general, identity-based encryption (IBE) does not support an efficient revocation procedure. In ACM CCS'08, Boldyreva et al. proposed revocable identity-based encryption( RIBE), which enables us to efficiently revoke (malicious) users in IBE. In PKC 2013, Seo and Emura introduced an additional security notion for RIBE, called decryption key exposure resistance(DKER). Roughly speaking, RIBE with DKER guarantees that the security is not compromised even if an adversary gets (a number of) short-term decryption keys. Therefore, DKER captures realistic scenarios and is an important notion. In this paper, we introduce bounded decryption key exposure resistance(B-DKER), where an adversary is allowed to get a-priori bounded number of short-term decryption keys in the security game. B-DKER is a weak version of DKER, but it seems to be sufficient for practical use. We obtain the following results: