An Algorithm of $(n,t)$-Threshold Proxy Signature with an Arbitrator

The paper presents an $(n,t)$-threshold proxy signature scheme with an Arbitrator which enables an original signer to delegate the signature authority to sign a message on behalf of the original signer to proxy group $\frak P$ of n members. The original signer distributes the proxy key among the proxy group members in such a way that not less then $t$ proxy signers and the Arbitrator can cooperatively sign messages on behalf of the original signer. Thus, for signing the document it is necessary to have agreements of not less then $t$ members. The Arbitrator is a trusted third party. It receives the information from the $t$ members and completes the calculation of the digital signature. A verifier can identify the original signer and the members of the proxy group $\frak P$. The main feature is that $n$ members of the proxy group can not calculate the proxy key and the original signer's secret key.