Structured multisignature algorithms

A structured multisignature scheme is an order-sensitive multisignature scheme that allows participating signers to sign messages in compliance with a specified signing order. It has been shown that the Burmester et al. order-sensitive multisignature scheme cannot prevent all signers producing a valid multisignature without following the specified signing order. The paper proposes two structured multisignature algorithms, one based on the RSA scheme and the other on an ElGamal-type scheme. Incorporation of both order-free and order-sensitive multisignature algorithms together is shown to construct a generalised multisignature algorithm.