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Comment by tmlee | Hacker News Reader

No hardware can protect itself from absolute physical compromise; perhaps a self-fuse burner when somebody tries to open it

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Banks store private keys for their ATMs in hardware security modules (HSM) and there are lots of crypto exchanges that started doing that. One of the features is private keys self destruct when tampering is detected. If you have a backup you’ll be able to recover the private key. While I agree that Trezor wasn’t designed with this in mind, I think it’s a good idea to include this feature. Not sure about the size requirements for that though, it might make the device significantly bigger.

Size requirements shouldn't be intensive, assuming it's a single-shot system. All you need is 128-256 bits worth of secret key data that is physically-destructible (e.g. with a high voltage spike). You then encrypt/decrypt the rest of the secrets stored in the device with this destructible key.

True HSM with active self destruct needs to be constantly powered. On the other hand for many if not most applications, typical secure smart-card is is completely sufficient (and in fact typical POS card terminal stores most of it's long term secrets on SIM-like smart-card).

Somewhere in my junk parts bin is such a PCI card I bought out of a junk bin at Akihabara, that has Mitsubishi logo clearly printed with archaic construction overall, apparently marketed by NEC somehow, which product brochure page disappeared after I mentioned it on Twitter,

Had a pair of blown AA battery for self destruction. I never bothered to get it working, but IIRC it was supposed to detect removal from PCI slot(the proper) to self erase. So it’s not rare or difficult.

At this years RWC someone fuzzed the software on the HSM. Keys came out.

Thanks for sharing this, I had to google RWC. For others that don’t know the acronym: https://rwc.iacr.org

Bigger may be better.

After all these devices are hard to use in part because if the tiny screens.

Since most of the time you don't carry them in your pocket it does not appear to be a problem if they are bigger.

Doesn't the iPhone claim to be able to protect from physical access?

That’s what the US Department of Justice claims, at least.

Let's agree that protection against physical access is extremely difficult.

With the right systems in place, you can be protected from physical compromise. For example, if my credit card is stolen, I call visa and I'm fine.

And who do you think foots the bill? You might not pay it in one lump sum, but I’m pretty sure you still pay it.

People who lost 100% of their coins are probably wishing they had the option to buy some kind of insurance. But no, be your own bank. (Wait, don't real banks also have insurance?)

Crypto is digital cash, not digital credit. If someone steals your physical wallet, you generally aren’t getting that cash back. Can we please dispense with this kind of hyperbolic nonsense?

You wouldn't carry large sums of cash on your person, so why are people considering large piles of cryptocurrency?

People actually carry large sums in many places where credit cards aren't prevalent. Like Japan.

The analogy isn't credit. It's a bank. I doubt people carry much of a percent of their total Yen wealth in their pockets.

The merchants who accepted the fraudulent credit card transactions don't get their money from Visa. So the merchants pay.

... and factor this into their pricing, completing the circle.

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