Abstract: In secure multicast communication, packet source authentication is abottleneck problem due to the dynamic property of the multicast group,unreliability of data transmission and the large number of data packets.This paper proposes a novel authentication scheme called B-MSAS (BalanceMulticast Source Authentication Scheme) that can be used tosolve this problem, in which a new message authentication technique isintroduced. This scheme dramatically reduces the signature size overheadand raises the signature rate. It provides the non-repudiation service,high loss resistance, and can easily be scaled up to potentiallymillions of receivers, and hence has a sweeping applicability. It shouldhave applications to many practical problems.