INFORMATICA International Journal Main Page Editorial Board Abstracting/Indexing Instructions to Authors Subscription Information Contents Author Index Papers in Production		INFORMATICA, 2007, Vol. 18, No. 1, 55-60 © Institute of Mathematics and Informatics, ISSN 0868-4952 On the Proxy-Protected Property of Chen et al.'s Proxy Multisignature Schemes Pei-Hui HUANG, Hsiang-An WEN, Chih-Hung WANG, Tzonelih HWANG ^1Department of Computer Science and Information Engineering National Cheng Kung University Tainan, Taiwan, R.O.C. E-mail: pehui@ismail.csie.ncku.edu.tw, hwangtl@ismail.csie.ncku.edu.tw ^2Department of Computer Science and Information Engineering Leader University Tainan, Taiwan, R.O.C. E-mail: reinhard@ismail.csie.ncku.edu.tw ^3Department of Computer Science and Information Engineering National Chiayi University Chiayi, Taiwan, R.O.C. E-mail: wangch@mail.ncyu.edu.tw Abstract Recently, Chen, Chung, and Huang proposed a traceable proxy multisignature scheme based on the elliptic curve cryptosystem. However, this paper shows that the original signers can produce a valid signature as the proxy signer does in the proxy protected scheme. Therefore, Chen et al.'s proxy-protected scheme cannot protect the proxy signer from being forged by the original signers. We further find that the early work of Chen et al. in 2003 suffers the same attack. To overcome this problem, an improved scheme will be presented. Keywords: proxy signature, proxy multisignature, proxy-protected, elliptic curve, digital signature To preview Lithuanian abstract see full article text To preview full article text in PDF format click here You could obtain free Acrobat Reader from Adobe
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