\indent \,\, In this paper, we propose the first key-exposure free chameleon hash and signature scheme based on discrete logarithm systems, without using the gap Diffile-Hellman groups. This provides more flexible constructions of efficient key-exposure free chameleon hash and signature schemes. Moreover, one distinguishing advantage of the resulting chameleon signature scheme is that the property of ``message hiding" or ``message recovery" can be achieved freely by the signer, $i.e.,$ the signer can efficiently prove which message was the original one if he desires.
Category / Keywords: public-key cryptography / Chameleon hashing, Gap Diffie-Hellman group, Key exposure Date: received 16 Jan 2009, last revised 13 Aug 2009 Contact author: isschxf at mail sysu edu cn Available format(s): PDF | BibTeX Citation Version: 20090813:141722 (All versions of this report) Short URL: ia.cr/2009/035