Jae Hong Seo

Boneh and Franklin gave a naive revocation method in identity-based encryption (IBE) which imposes a huge overhead into the key generation center. Later, Boldyreva, Goyal, and Kumar proposed an elegant way of achieving an IBE with efficient revocation, called revocable IBE (RIBE). In this paper, we revisit RIBE from the viewpoint of both security models and constructions. First, we introduce a realistic threat, which we call decryption key exposure, and show that all prior RIBE constructions, ex

Efficient and privacy-preserving constructions for search functionality on encrypted data is important issues for data outsourcing, and data retrieval, etc. Fully secure anonymous Hierarchical ID-Based Encryption (HIBE) schemes is useful primitives that can be applicable to searchable encryptions [4], such as ID-based searchable encryption, temporary searchable encryption [1], and anonymous forward secure HIBE [9]. We propose a fully secure anonymous HIBE scheme with constant size ciphertexts. k

In this article, we identify a flaw in Huang et al.'s public key encryption with authorized equality test (The Computer Journal, 2015). More precisely, we point out that the proof of the indistinguishability under adaptive chosen ciphertext attack (IND-CCA2) security for their scheme has a serious flaw. We illustrate this flaw by presenting a polynomial time CCA2 attack on their scheme. We also provide a solution to correct this flaw by modifying their scheme slightly. Our solution is quite effi