Broadcast communication prevails for data dissemination and resource discovery. In mission-critical applications, extensive information sharing and coordination endow broadcast with new features: a large number of active broadcast sources, probabilistic broadcast reception and high receiving rate. We identify this type of broadcast traffic as ASPBeast traffic. Many efforts have been made to authenticate broadcast source and prevent content modification in a light-weighted way using oneway hash chain (TESLA). However, they do not scale to a large number of senders. In addition, authentication delay increases under packet losses and probabilistic broadcast. The longer authentication is postponed, the longer packets are buffered, which poses a memory-based denial-of-service (DoS) threat. In this paper, we will present an efficient authentication protocol for ASPBeast traffic, called ChainFarm. We propose an algorithm for parameter configuration to satisfy both memory and delay requirements with maximal resilience against compromise. Simulation results agree with our analysis and show distinct performance improvement.