[marktangotango]

Concealing algorithms and executable code is actually very difficult, consider that to run, a program must first be decrypted. Also consider the decades long war between crackers and proprietary software creators. Obfuscating algorithms has been the subject of quite a lot of academic research.

[rtkwe]

Store the decryption key in a removable module or the wireless controller? Then anyone who captures one is stuck with a ball of encrypted code that can't execute. Dealing with securing software and keys against capture is not new for the military.

Also destroying the hdd/ssd is easier than destroying the whole machine. You could even have a secure wipe option if the machine is still able to run it's computer but is disabled mechanically.

[JabavuAdams]

Yup, I'm sure the countermeasures you can think of in the time required to write an HN post will be secure against technically-advanced nations' militaries.

[grogenaut]

I was thinking more along the lines of thermite