A digital multisignature scheme based on the Fiat-Shamir scheme

We show the sequential multisignature scheme based on the Fiat-Shamir scheme which is a slight variant of simultaneous multisignature scheme, and discuss the security of a digital multisignature scheme. The following properties are proven;(1)The difficulty of deriving secret information from public information in a multisignature scheme with already used signatures is equivalent to that of deriving it in a single signature scheme; and(2)The difficulty of forging a partial multisignature so that the total multisignature is valid is equivalent to that of deriving a single signature in the Fiat-Shamir scheme.