An improved structured multi-signature scheme

Structured multi-signatures is a special multi-signature which multiple signer can cooperate to sign the same message and it provided co-signers with different role/position have different management liability and authorization capability. There are lots of structured multi-signature schemes such as Harn´s scheme and other schemes. This paper shows some insecurity in these schemes, and the schemes can not resist the forgery attack. Then this paper proposed a new structure multi-signature scheme based on the difficulty of the discrete logarithm problem with verifying signature parameter and signers´ public keys. The computation cost and the size of the structured multi-signature is fixed and has independent of the number of signature members. By verifying public-key, the new scheme can resist lots of outsider attack and insider attack. The validity of the new scheme can be verified, and it is a secure signature scheme. In this way, the improved schemes can resist attacks as above mentioned.