Abstract:

The multi-signature provides that multiple signers can cooperate to sign the same message，which can be used in cloudy security. Burmester. proposed a structured multi-signature compare with other multi-signature，the scheme was more secure，and it provided co-signers with different role／position have different management liability and authorization capability. But this scheme was not safety enough because the scheme was very easy aggressed by the forgery attack，and the paper gives the corresponding attacks to the scheme. At last，this paper proposes an improved multi-signature scheme with verifying signature parameter，in this method，the new scheme can resist attacks as above mentioned. And the length of the signature in the new scheme is independent of the number of signature members.

Key words: multi-signature, structured multi-signature, forgery attack, hash function, primitive-root