Threshold RSA for Dynamic and Ad-Hoc Groups

We consider the use of threshold signatures in adhoc and dynamic groups such as MANETs (“mobile ad-hoc networks”). We first show that known threshold RSA signatures (in particular the most efficient known scheme due to Shoup) are not practical enough for realistic use in these highly-constrained environments. Our contribution is in presenting variants of Shoup’s protocol that provide the efficiency and flexibility needed in ad-hoc groups, and add the capability of incorporating new members (share-holders) to the group of potential signers without relying on central authorities. The schemes are efficient, fully non-interactive and do not assume broadcast.