Emergency method to erase all data off a machine within seconds
Thermite.
Thermite burns at a temperature of thousands of degrees centigrade, which would be more than sufficient to destroy all the data stored in any modern data storage medium. It is also already used by militaries for the targeted destruction of equipment. Additionally, according to Wikipedia:
For example, thermite can be used for the emergency destruction of cryptographic equipment when there is a danger that it might be captured by enemy troops.
There are two DEFCON videos from 2012 and 2015 exploring this exact issue:
- DEFCON 19: And That's How I Lost My Eye: Exploring Emergency Data Destruction
- DEFCON 23: And That's How I Lost My Other Eye...Explorations in Data Destruction (Fixed)
Summary of Viable Options
- Plasma Cutter
- Oxygen Injection (Difficult setup)
- Nailguns (depending on adversary)
- Damped High Explosives (Lots of kinetic energy)
- HV Power Spike (Inconclusive forensics)
In essence, your only viable methods are physical destruction
If you trust encryption then you could encrypt your entire drive using
- Linux: LUKS (supported by all major distributions)
- Windows: BitLocker
As soon as you physically switch off the device, all the information turns into random noise which no one will be able to recover unless he/she has the decryption key. However, this method has a major shortcoming: your adversary will know you've got encrypted data and they may force you to spill your secrets.
As for Linux LUKS: if you wipe the first megabyte block of your encrypted partition, the data can no longer be recovered under any circumstances even if you know the key.
If you don't want the adversary to even suspect anything you could use VeraCrypt or DiskCryptor (formerly TrueCrypt) which can create hidden encrypted partitions/containers, but those still can be discovered given enough persistence.
Lastly I'd personally do the following under these circumstances given you have a satellite connection available:
Run the entire system off a live Linux CD and store the data in an encrypted cloud (private or commercial). In this case the adversary will never even be able to deduct anything from your e.g. laptop which may contain a run-of-the-mill Windows OS with pictures of cats.
Also take a look at:
- https://www.securedrive.com/product/compare
- http://www.runcore.com/en/product.php?cid=143
- https://datalocker.com/product/datalocker-dl3/