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Comment by DenisM | Hacker News Reader

I often wonder if the only secure computing and communication these days is an air-gapped computer.

The data can be manipulated there and then copied to another computer using... uh... a writeable compact disk? USB drives are hard to trust given how much software is running on them, so... maybe CF cards too?

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You want data diodes that physically enforce one-way-only data transfer.

Tin Foil Chat[1] has a circuit for an opto-isolator based data diode and a discussion of how to use them for secure chat. It's probably not hard to modify these plans for other uses, if the specific guarantees that TFC provides are compatible with your secure computing requirements.

[1] https://cs.helsinki.fi/u/oottela/tfc.pdf

Routing the data through a central IM server is a huge problem, it would still allow one to figure out who is talking to who and when.

It's not hard to adapt. He regularly improved it based on our feedback at Schneier's blog. I speculated that a higher bandwidth would allow audio and video using same architecture. It's a great desigm regardless due yo strong confidentiality despite endpoint attacks.

Very interesting... so one machine for sending data (one-way channel) and another machine fro receiving data (also a one-way channel). That, in combination with a one-way serial port, might just suffice.

>I often wonder if the only secure computing and communication these days is an air-gapped computer.

Some security experts say air-gapping is not the best approach. Consider Qubes OS instead.

"How does Qubes OS compare to using a separate physical machine?", https://www.qubes-os.org/tour/

None of that will help if the on-chip (CPU) code is hostile. Once the CPU itself is compromised, preventing connections is the only way to contain the problem.

I read somewhere that a transmit only serial connection is a good solution.

Ha... that might just work!

Install a VM on an air-gapped computer, use a guest OS to zip & encrypt the data you want to transfer, dump that zip on a disc, and unpack/decrypt it inside another VM on the destination computer?

Outgoing, secret data plus incoming, malicious data sharing hardware is where security problems start. Ottela keeps those separate physically. Prevents many types of attack or unnecessary complexity.

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