A structured multi-signature scheme and its security proof

A new structured multi-signature scheme is proposed based on a sequential multi-signature scheme. The advantages of the proposed scheme are as follows: the multi-signature is a co-signature which is generated by multiple signers in collaborative, rather than accumulating per signer´s single signature; the order of signature doesn´t need to be fixed beforehand; any secret messages can be transmitted between different signers with confidentiality and integrality guarantee in the scheme; the length of signature is independent of signer´s number. The proposed scheme can against existing attacks to multi-signature. The security of scheme is proved based on the difficulty assumption of factoring and quadratic residue in the random oracle model.