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by mistahenry
2329 days ago
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IMO there's a huge difference between invasive and non-invasive attacks. I would expect something that bills itself as "The safe place for your coins" to require a bit more effort, know-how, and tools to read out my keys than "a couple hundred dollars of equipment" and a python program. > if anyone has physical access it's game over It's actually not when you use a series of common defenses that wipe the chip when tampering is detected. Of course it's still possible to determine the private keys via perfectly executed microprobing...but there's a huge difference here. Invasive attacks require significant time in very expensive laboratories per attack, which very well may fail. Let's say managed to steal my wallet which leverages a secure element with tampering protection. If you're unaware that voltage/clock glitching will wipe the device, you may try and then you've lost. But let's say you're aware so you want to go the microprobing route. Do you have the necessary lasers and acids to get directly to the circuitry you want to read out without accidentally compromising the integrity of the top-layer sensor meshes? Do you possess a focused ion beam station (only costs ~500k USD)? By using this mesh I've made the extraction significantly more tedious and requiring far higher levels of precision for you. You've got my smart card, but I wouldn't call it "Game Over" by any means. Maybe in this amount of time I figured out that my wallet is missing. This attack here on the Tresor, though, requires physical access but can be automated. Here, physical access really is game over. I would rate this issue as "Trezor shows themselves to be an inferior solution, will not use to store my keys" Read here if you want to see more on techniques for readout and known countermeasures. https://www.cl.cam.ac.uk/~mgk25/sc99-tamper.pdf |
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