A host processing device instructs a plurality of data processing (DP) accelerators to configure themselves for secure communications. The host device generates an adjacency table of each of the plurality of DP accelerators. Then the host device then establishes a session key communication with each DP accelerator and sends the DP accelerator a list of other DP accelerators that the DP accelerator is to establish a session key with, for secure communications between the DP accelerators. The DP accelerator establishes a different session key for each pair of the plurality of DP accelerators. When all DP accelerators have established a session key for communication with other DP accelerators, according to the respective list of other DP accelerators sent by the host device, then the host device can assign work tasks for performance by a plurality of DP accelerators, each communicating over a separately secured communication channel.