## CryptoDB

### Paper: How to Construct Space Efficient Revocable IBE from Non-monotonic ABE

Authors: Huang Lin Zhenfu Cao Muxin Zhou Haojin Zhu URL: http://eprint.iacr.org/2010/119 Search ePrint Search Google 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.
##### BibTeX
@misc{eprint-2010-23020,
title={How to Construct Space Efficient Revocable IBE from Non-monotonic ABE},
booktitle={IACR Eprint archive},
keywords={public-key cryptography / Revocable IBE, Non-monotonic, Attribute based encryption},
url={http://eprint.iacr.org/2010/119},
note={ faustlin@sjtu.edu.cn 14677 received 4 Mar 2010, withdrawn 8 Mar 2010},
author={Huang Lin and Zhenfu Cao and Muxin Zhou and Haojin Zhu},
year=2010
}