Hacker News Reader

Comment by jclulow | Hacker News Reader

You can't really "add" your key to a computer you don't trust, though. At best, it could destroy your USB device; at worst it could copy the contents out once you decrypt them.

This may be better than using one password for everything, but it's certainly not a panacea.

View on HN

Maybe the only answer is to air-gap the two devices and have the user input a secret code shown on the dongle. So you press the button, type the code on the website and log in that way.

Edit: Or maybe have two devices: one dumb flash storage and a device that actually computes your key. You press the "compute my key" button while the storage is connected to the keychain, then disconnect it from the keychain and connect it to the pc. Next time you connect it to the keychain, it's wiped before use and never ever read.

The device could instead have a display that displays a password, QR code, one-time-key, etc... and then you would scan it using a webcam or your phone (or type it manually).

Yeah, but that way it's displayed out in the open and you can make a mistake copying it. I think just exchanging usb flash storage sticks is preferable unless you sufficiently distrust the system you're on.

Maybe like a phone running a TOTP application?

I would have more trust in a separate device that has no networking capabilities.

What if it's in a "secure element" whose hardware and firmware make it provably incapable of divulging the private key?

I don't think that's possible... it reminds me of Apple saying that they can't decrypt your phone, but it is decrypted when you use it and many apps have permissions to transfer basically everything over the network (and Apple has root too).

I think the panacea is dedicated hardware that can produce secure tokens (a signed message) without having to expose my key to the machine I plug into. But existing systems still require that level of trust; I'm doing no worse than someone with a password typing it into a possibly insecure machine.

You could also catch BadUSB...

Reply on news.ycombinator.com