Authentication is an important security measure for multicast applications, providing receivers with confidence that the packets they receive are valid. Simply signing every multicast packet with a digital signature incurs high overhead; therefore, a scheme such as signature amortization helps reduce this overhead. To tolerate packet loss, erasure codes are employed to enhance signature amortization. However, the use of erasure codes introduces pollution attack, an attack in which the adversary injects packets to disrupt the erasure decoding procedure and consequently denies the authentication service to the receiver. Unfortunately, current solutions to pollution attack are computationally intensive and inefficient. To cope with this problem, we propose a new lightweight, pollution-attack resistant multicast authentication scheme (PARM), which generates evidence that receivers can validate on a fast, per-packet basis. This approach effectively resists pollution attacks and has better performance than previously proposed solutions.