An Improved Efficient Multisignature Scheme in Group Communication Systems
Debasis Giri, Parmeshwary Dayal Srivastava · 2007
Digital multisignature is signed by multiple signers with the knowledge of multiple private keys and can be verified based on all signers' public keys. In 2004, Rahul et al. pro- posed a multisignature scheme for implementing safe de- livery rule in group communication systems. In 2005, Das et al. pointed out weaknesses to forgery as well as signa- ture integrity attacks on Rahul et al.'s scheme. We show that the forgery attack of Das el al. on Rahul et al.'s scheme is infeasible. Further, the drawbacks of Rahul et al.'s and Das et al.'s schemes are that the size of multisignature and the computational time for verification of multisignature in- crease as the number of signers in a group increases. In this paper, we propose the improvement of Rahul et al.'s scheme to overcome these weaknesses. Even if there be an arbitrary number of signers in a group, in our scheme, the computa- tion for verification time of multisignature and the size of multisignature are independent of the number of signers in that group. In addition, our scheme is more secure and effi- cient compared to the previously published schemes. Keywords: Cryptography, Digital signature, Multisigna- ture, Attacks