Broadcast is an important communication method in WSN (Wireless Sensor Network), thus broadcast authentication naturally becomes a critical security service in WSN, by which a node can determine whether to receive or to drop a message. In this paper, a brief introduction of typical broadcast algorithm is given, such as mu TESLA, all of the exist method suffer from some kind of deficiency. By analysis of the methods and algorithms existed, a new broadcast algorithm based on Merkle tree is proposed, which categorizes broadcast into two category, single packet and multi-packet broadcast. For different broadcast, different process method is used to reduce the size of the MAC (Message Authentication Code) of the broadcast message. At last, analysis and evaluation is given, which shows the fore-mentioned method has following advantages: support of multi-sources broadcast, broadcast revocation, immediate authentication with no delay, and no need for time synchronization between the sources and the receivers.
