Digital signature scheme is an important research topic in cryptography. An ordinary digital signature scheme allows asigner to create signatures of documents and the generated signatures can be verified by any person. A proxy signaturescheme, a variation of ordinary digital signature scheme, enables a proxy signer to sign messages on behalf of the originalsigner. To be used in different applications, many proxy signatures schemes were proposed. Among them, Soe and Leenominative Proxy Signature scheme, and Jianhong Zhang, Jianhong Zou, and Yumin Wang nominative Proxy Signaturescheme for mobile communication. The authors of these schemes argued that their schemes satisfies the following securityrequirements: user anonymity, authentication and non-repudiation. However, in this paper, we show that their schemes donot satisfy the non-repudiation among their security requirements. And then we propose a new nominative proxy signaturescheme that solves the weakness of their schemes. Unlike their schemes, the proposed scheme provides a non-repudiationproperty and moreover it is more secure than their schemes.
展开▼
