Now you're thinking on the right lines! All of that should be fine. Didn't think about using USB for power: just had a strip in the design. Will have to think on it. Standardizing on Linux/BSD is wise, too, as it lets us easily adapt it to new software applications.
And, in case I forgot, you can modify this architecture for voice or video but will need to replace serial cable with higher bandwidth line. Risk starts to go up there. You either need a real data diode or must physically modify Ethernet/Fiber cables and/or cards to do one-way transmission. Might take custom, microcontroller board to be sure it's done right.
It's a bigger project to say the least. There's examples online but the security is debatable. That's why the defense sector builds and certifies the big guns [1]. That it takes them that much hardware & they mention TEMPEST hints at how much work goes into this one, tiny problem.
And, in case I forgot, you can modify this architecture for voice or video but will need to replace serial cable with higher bandwidth line. Risk starts to go up there. You either need a real data diode or must physically modify Ethernet/Fiber cables and/or cards to do one-way transmission. Might take custom, microcontroller board to be sure it's done right.
It's a bigger project to say the least. There's examples online but the security is debatable. That's why the defense sector builds and certifies the big guns [1]. That it takes them that much hardware & they mention TEMPEST hints at how much work goes into this one, tiny problem.
[1] http://www.nexor.com/sites/default/files/Nexor%20Datasheet%2...