Keeping WirelessHART conversations private

We join our gallant hero, W. L. Hart, as he enters the high-tech den of thieves run by The Manager.

As the door opened, Hart found himself confronted by a beautiful brunette with long hair and a short dress. “The Manager has assigned you the designation J-7. Follow me J-7.” She turned and walked down the corridor.

“Friendly place,” Hart thought. He had no choice but to follow her. The corridor opened into a large room filled with cubicles. The brunette led him to an empty one.

“This is your cubicle,” she explained. “Learn the designations of those around you.” With that, she walked away.

“I’m J-7,” Hart said to those working in the adjacent cubicles. There was a chorus of responses. “I’m C-12,” said one. “N-5 at your service,” stated another. Hart acknowledged each one, then sat at his terminal.

Almost immediately, a message appeared on his screen. With it, he began to discover just how difficult his assignment of infiltrating this network would be. “J-7, report your status. Respond using the Red code.” Every communication between members of the network was assigned a code. Without the code, it would be impossible to decipher the information being exchanged.

This was going to be a difficult assignment.

The Real World

In a WirelessHART network, every device knows the network key. This would allow every device to understand the transmission of every other device. It would also allow anyone able to get the network key to ease-drop on every network transmission.

For this reason, WirelessHART has an added layer of protection – the session key. This key is assigned by the network manager when it schedules a communication between two devices on the network. Certain information in the packet is transmitted publicly using the network key such as addressing and routing information. Other data in the packet is kept private using the session key.

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