Affiliations: Department 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 | Department of Computer Science and Information Engineering, Leader University Tainan, Taiwan, R.O.C., e-mail: reinhard@ismail.csie.ncku.edu.tw | Department 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
Journal: Informatica, vol. 18, no. 1, pp. 55-60, 2007
