## CryptoDB

### Paper: Key-Exposure Free Chameleon Hashing and Signatures Based on Discrete Logarithm Systems

Authors: Xiaofeng Chen Fangguo Zhang Haibo Tian Baodian Wei Kwangjo Kim URL: http://eprint.iacr.org/2009/035 Search ePrint Search Google Chameleon signatures are based on well established hash-and-sign paradigm, where a \emph{chameleon hash function} is used to compute the cryptographic message digest. Chameleon signatures simultaneously provide the properties of non-repudiation and non-transferability for the signed message. However, the initial constructions of chameleon signatures suffer from the problem of key exposure: the signature forgery results in the signer recovering the recipient's trapdoor information, $i.e.,$ the private key. This creates a strong disincentive for the recipient to forge signatures, partially undermining the concept of non-transferability. Recently, some specific constructions of key-exposure free chameleon hashing are presented, based on RSA or pairings, using the idea of Customized Identities". In this paper, we propose the first key-exposure free chameleon hash scheme based on discrete logarithm systems, without using the gap Diffile-Hellman groups. Moreover, one distinguished advantage of the resulting chameleon signature scheme is that the property of message hiding" or message recovery" can be achieved freely by the signer. Another main contribution in this paper is that we propose the first identity-based chameleon hash scheme without key exposure, which gives a positive answer for the open problem introduced by Ateniese and de Mederious in 2004.
##### BibTeX
@misc{eprint-2009-18270,
title={Key-Exposure Free Chameleon Hashing and Signatures Based on Discrete Logarithm Systems},
booktitle={IACR Eprint archive},
keywords={public-key cryptography / Chameleon hashing, Gap Diffie-Hellman group, Key exposure},
url={http://eprint.iacr.org/2009/035},
note={ isschxf@mail.sysu.edu.cn 14260 received 16 Jan 2009},
author={Xiaofeng Chen and Fangguo Zhang and Haibo Tian and Baodian Wei and Kwangjo Kim},
year=2009
}