Strongly unforgeable threshold multi‐proxy multi‐signature scheme with different proxy groups

In the majority of threshold multi‐proxy multi‐signature (TMPMS) schemes, only one proxy group is authorized to sign on behalf of all the original members. However, the original signers in various practical applications are often from different organizations. Each original signer should be able to designate a proxy group in his own organization; thus, each original signer could have distinct proxy members. However, this practical requirement of TMPMS schemes is seldom considered. To satisfy this requirement, we propose a new TMPMS scheme in which each original member can designate a proxy group in his own organization. Moreover, the threshold value of each proxy group is unique. We develop a security model to prove the high security and strong unforgeability of the proposed scheme. We analyze the security of our scheme based on the four types of adversaries tested in the security model. Compared with previous schemes, the new scheme offers higher security and superior computational efficiency. Copyright © 2013 John Wiley & Sons, Ltd.