A device, method, and system for processing communications for secure operation of industrial control system field devices, includes: a processing device to be placed in-line between a Master Telemetry Unit (MTU) and a field device. A software verified microkernel includes instructions for the processing device to provide a secure partitioning of memory between a communication network interface address space, a security cell address space, and a field device interface address space. The security cell address space includes instructions to: receive communication messages from the MTU via the communication network interface address space; authenticate a user identification of each communication message; verify that an operation requested in each message is authorized for the user identification; and send each communication message having an authenticated user identification and a verified operation to the field network interface address space for communication with the field device.