International Association for Cryptologic Research

International Association
for Cryptologic Research


Huang Lin


How to Construct Space Efficient Revocable IBE from Non-monotonic ABE
Since there always exists some users whose private keys are stolen or expired in practice, it is important for identity based encryption (IBE) system to provide a solution for revocation. The current most efficient revocable IBE system has a private key of size $\mathcal{O}(\log n)$ and update information of size $\mathcal{O}(r \log(\frac{n}{r}))$ where $r$ is the number of revoked users. We describe a new revocable IBE systems where the private key only contains two group elements and the update information size is $\mathcal{O}(r)$. To our best knowledge, the proposed constructions serve as the most efficient revocable IBE constructions in terms of space cost. Besides, this construction also provides a generic methodology to transform a non-monotonic attribute based encryption into a revocable IBE scheme. This paper also demonstrates how the proposed method can be employed to present an efficient revocable hierarchical IBE scheme.
Cryptanalysis of An Oblivious Polynomial Evaluation Protocol Based On Polynomial Reconstruction Problem
Huang Lin Zhenfu Cao
In 1999, Naor and Pinkas \cite {NP99} presented a useful protocol called oblivious polynomial evaluation(OPE). In this paper, the cryptanalysis of the OPE protocol is presented. It's shown that the receiver can successfully get the sender's secret polynomial $P$ after executing the OPE protocol only once, which means the privacy of the sender can be violated and the security of the OPE protocol will be broken. It's also proven that the complexity of the cryptanalysis is the same with the corresponding protocols cryptanalyzed.
Short Group Signature without Random Oracles
We construct a short group signature which is proven secure without random oracles. By making certain reasonable assumptions and applying the technique of non-interactive proof system, we prove that our scheme is full anonymity and full traceability. Compared with other related works, such as BW06, BW07, ours is more practical due to the short size of both public key and group signature.


Zhenfu Cao (3)
Xiaohui Liang (1)
Jun Shao (1)
Muxin Zhou (1)
Haojin Zhu (1)