Blind Collective Signature Protocol Based on Discrete Logarithm Problem

Using Schnorr’s digital signature (DS) scheme as the underlying scheme there is designed the collective DS protocol. In the proposed collective DS protocol the signature is formed simultaneously by all signers, therefore using this protocol leads to natural solution of the problem of signing simultaneously a contract. Using the proposed collective DS protocol the blind collective DS protocol has been designed, which is a new type of the multi-signature schemes. For simultaneous signing a package of different contracts by different sets of signers it is proposed another new multi-signature scheme called composite signature.