3 ms·

Awhile back, I was looking at using a TREZOR as a U2F key. I liked it since the interface looked good, confirmation of sending the key on the device itself, an

by kxyvr 8y ago

Awhile back, I was looking at using a TREZOR as a U2F key. I liked it since the interface looked good, confirmation of sending the key on the device itself, and the software was open source. For those two reasons, it looked nicer than using a Yubikey, which closed it source with the Yubikey 4 and didn't provide confirmation on the device itself. That said, this attack didn't make the TREZOR look great. What's a good option for a U2F key? On a similar topic, with WebAuthn, is it worth waiting for FIDO2 keys?

sturmeh 8y ago
Yubikey of course, however there's no reason you can't use the TREZOR, just update the firmware and regenerate the seed if you think your device may have been compromised in the meantime. I think it's worth considering that these attacks are problematic in theory, but they still require quite a bit of access and opportunity.
Fnoord 8y ago
I recommend to use 2FA asap. Whatever implementation is better than none, though it depends on your attack surface/vector and even on the question how good your 1st factor is (your password). You can get a cheap, good YubiKey which is U2F/FIDO2 certified for 20 USD/EUR [1]. These communicate over USB-A or USB-C depending on the one you buy. We're in a transition of USB-A to USB-C that's always a rough time. Do you go for backwards compatibility, the (better) future standard, or both (buying two)? If you prefer Bluetooth or NFC the one I mentioned above is too limited. Then Google recommends a Feitan for the former, and I recommend a YubiKey NEO for the latter. YubiKey NEO is also open source. With regards to TREZOR/Ledger, 2FA usage is more of a nice by-product. People buy it as Bitcoin wallet 2FA and that it can be used for more is an afterthought. One that can save you a couple of bucks though. Either way I recommend at least 1 2FA backup. Could be codes, or an app, or a second YubiKey, or even SMS. Though, obviously, each of these has their weaknesses you could host the codes in e.g. cryptosteel [2] at a notary. I plan to do that with my important passwords (ie. the password for my password manager). [1] https://www.yubico.com/product/security-key-by-yubico/ https://www.yubico.com/product/security-key-by-yubico/ [2] https://cryptosteel.com/ https://cryptosteel.com/
sowbug 8y ago
If your personal threat model includes physical attacks on a U2F key, then it's unlikely the key is the weak link. The attacker would more likely use that physical access to root your computer. If your threat model does not include physical attacks, then any U2F device (except software-based ones) is fine.

by kxyvr 8y ago

sturmeh 8y ago

Yubikey of course, however there's no reason you can't use the TREZOR, just update the firmware and regenerate the seed if you think your device may have been compromised in the meantime. I think it's worth considering that these attacks are problematic in theory, but they still require quite a bit of access and opportunity.

Fnoord 8y ago

I recommend to use 2FA asap. Whatever implementation is better than none, though it depends on your attack surface/vector and even on the question how good your 1st factor is (your password). You can get a cheap, good YubiKey which is U2F/FIDO2 certified for 20 USD/EUR [1]. These communicate over USB-A or USB-C depending on the one you buy. We're in a transition of USB-A to USB-C that's always a rough time. Do you go for backwards compatibility, the (better) future standard, or both (buying two)? If you prefer Bluetooth or NFC the one I mentioned above is too limited. Then Google recommends a Feitan for the former, and I recommend a YubiKey NEO for the latter. YubiKey NEO is also open source. With regards to TREZOR/Ledger, 2FA usage is more of a nice by-product. People buy it as Bitcoin wallet 2FA and that it can be used for more is an afterthought. One that can save you a couple of bucks though. Either way I recommend at least 1 2FA backup. Could be codes, or an app, or a second YubiKey, or even SMS. Though, obviously, each of these has their weaknesses you could host the codes in e.g. cryptosteel [2] at a notary. I plan to do that with my important passwords (ie. the password for my password manager). [1] https://www.yubico.com/product/security-key-by-yubico/ https://www.yubico.com/product/security-key-by-yubico/ [2] https://cryptosteel.com/ https://cryptosteel.com/

sowbug 8y ago

If your personal threat model includes physical attacks on a U2F key, then it's unlikely the key is the weak link. The attacker would more likely use that physical access to root your computer. If your threat model does not include physical attacks, then any U2F device (except software-based ones) is fine.