3 ms·

This is important to note : you don't need a hardware key to prevent phishing this way. This all could be accomplished with software.

tialaramex 8y ago
However, unless there is specialist hardware (which might be baked into your iPhone etcetera rather than a separate token) there's a risk bad guys steal the secret key via another route and then you're in a world of pain. Secret Key USB or NFC devices also more resemble other physical keys for which users already have some useful intuitions we can leverage.
- peterwwillis 8y ago
  You can still hack the U2F software in the browser and steal the key. If an attacker is local, the game is over. The only thing the button does is limit how many opportunities the attacker has. Almost all practical attacks are against a key stored on a server somewhere, a key in flight on the network, or a lack of security in the client. If we properly secure these aspects of access, we don't need a whole lot of extra layers, which are only workarounds for the actual root problems.
  - tialaramex 8y ago
    "Steal the key"? Steal WHAT key? In the cheap mass-produced FIDO tokens we mostly care about the only keys anybody is storing are 1. a single secret symmetric key inside the token. It has no reason to give this up to anybody, and no API for doing so; 2. _public_ keys used to check credentials If you're thinking "Wait, that can't be right, where do the corresponding _private_ keys live?" then Bzzzt, time to go read the FIDO/U2F specification before writing anything else on Hacker News. The whole point of this type of design is that even if the attacker has local code execution you haven't lost. An attacker with local code execution _plus a button press_ gets not a key which can be stolen but a single proof of control of their choice. It's like stealing a single OTP code, it's not _nothing_ but it's very far from everything.

tialaramex 8y ago

However, unless there is specialist hardware (which might be baked into your iPhone etcetera rather than a separate token) there's a risk bad guys steal the secret key via another route and then you're in a world of pain. Secret Key USB or NFC devices also more resemble other physical keys for which users already have some useful intuitions we can leverage.

peterwwillis 8y ago
You can still hack the U2F software in the browser and steal the key. If an attacker is local, the game is over. The only thing the button does is limit how many opportunities the attacker has. Almost all practical attacks are against a key stored on a server somewhere, a key in flight on the network, or a lack of security in the client. If we properly secure these aspects of access, we don't need a whole lot of extra layers, which are only workarounds for the actual root problems.
- tialaramex 8y ago
  "Steal the key"? Steal WHAT key? In the cheap mass-produced FIDO tokens we mostly care about the only keys anybody is storing are 1. a single secret symmetric key inside the token. It has no reason to give this up to anybody, and no API for doing so; 2. _public_ keys used to check credentials If you're thinking "Wait, that can't be right, where do the corresponding _private_ keys live?" then Bzzzt, time to go read the FIDO/U2F specification before writing anything else on Hacker News. The whole point of this type of design is that even if the attacker has local code execution you haven't lost. An attacker with local code execution _plus a button press_ gets not a key which can be stolen but a single proof of control of their choice. It's like stealing a single OTP code, it's not _nothing_ but it's very far from everything.