A Modified and Practical ThresholdProxy Signature Scheme Based onRSA

Wen etal.recently showedHwang'sThreshold Proxy Signature SchemebasedonRSA hassomemistakes ofequation and whichmakesitinsecure. Sotheymodified Hwang's scheme. However, we findthecoreoftheproblem ofthevalueofLagrange coefficient isstill notsolved andtheright ofproxysignature combiner isn't defined clearly inmodified scheme. We modify Hwang's schemeoncemoreourmodified schemeneedn't computetheinverse whenwe computethevalueof Lagrangecoefficient. Furthermore, inourmodified schemeproxy signature combiner don'tknowthe Eulerfunction value0(No) whichcanprevent combiner andpartial signer fromtheconspiracy attack. Theimprovement makestheschemeperfect andpractical.