  We analyse a communication scenario over a particular causal broadcast
channel whose state depends on a modulo sum. The receivers of the broadcast
receive channel state information and collaborate to determine the channel
state as to decode their private messages. Further, the receivers of the
broadcast can collude up to the minimum non-collusion condition to determine
state information of the other non-colluding receivers. We analyse three
resource scenarios for the receivers: receivers can share entanglement without
classically communicating, can just use classical communication, or have both
entanglement and classical communication. Using results from secure multi-party
communication, we find that when the receivers can share entanglement and
communicate classically, they can receive messages from the sender at a
non-zero rate with verifiable secure collaboration. In the entanglement only
case a positive capacity is not possible. In the classical communication case,
a non-zero rate of communication is achievable but the communication complexity
overhead grows quadratically in the number of receivers versus linear in the
number of receivers with entanglement.
