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Ledger (https://www.ledger.com https://www.ledger.com) supports FIDO and lets you do backups. You really need a screen to do it correctly, otherwise there is li

Ledger (https://www.ledger.com https://www.ledger.com) supports FIDO and lets you do backups. You really need a screen to do it correctly, otherwise there is little point in having an external device.

diggernet 4y ago
TacticalCoder has previously commented here (https://news.ycombinator.com/item?id=26844019 https://news.ycombinator.com/item?id=26844019) about the ability to set a specific seed on Ledger devices, so you can make a backup key that behaves identically to your main key.
lxgr 4y ago
This might be true for cryptocurrency transaction initiation, but in the WebAuthN model, what's the benefit of having a screen? The result of a WebAuthN challenge procedure is almost always a session cookie (TLS channel binding if you're really fancy), so the only thing that an authenticator could display on your screen is "do you want to authenticate as user x to website y", which arguably does not add that much value.
- tialaramex 4y ago
  The comment you're replying to is about cloning WebAuthn credentials. This is a delicate operation, because you are effectively cloning your entire identity. So yeah, a screen seems reasonable for that purpose.
- nybble41 4y ago
  > … so the only thing that an authenticator could display on your screen is "do you want to authenticate as user x to website y" … That is exactly why you want it. Consider, for a moment, that you have a key which is used to log in to your bank account and some other, much less critical site. Perhaps a GitHub account where you store some hobby projects. Without an unforgeable indication on the authenticator to show what you're logging in to, malware can wait until you're logging in to the second site, and thus expecting a prompt to use the authenticator, but actually trigger the authentication process for your bank off-screen. You tap the button or whatever on the authenticator thinking that you're logging in to your GitHub account but actually all your money is being siphoned off to who-knows-where. A key that signs whatever request is presented to it without any indication to the user of what the request actually was is dangerous.
  - lxgr 4y ago
    If you have malware on your computer (that can compromise the browser), it can just wait until you actually log in to your bank and then grab the session cookie/proxy away your authentication. It's a different story if the operation you are confirming with a security key actually can be rendered on the display, e.g. "pay $100 to someshop.com" (as in SPC [1]). In that scenario, there is actually nothing to steal except for the signed message itself, which would be useless to anybody that's not someshop.com, but given that WebAuthN almost always just yields a session cookie, I don't really see the benefit. [1] https://www.w3.org/TR/secure-payment-confirmation/ https://www.w3.org/TR/secure-payment-confirmation/
    - nybble41 4y ago
      > If you have malware on your computer (that can compromise the browser), it can just wait until you actually log in to your bank and then grab the session cookie/proxy away your authentication. Sure, but you might never log in to your bank from this particular computer precisely because you don't trust it. But you think it's fine to log in to your hobby account since that doesn't store anything you really consider important. If you assume there is never any malware on the host then you don't need the key at all—the host can store the secrets and handle the authentication on its own.
      - lxgr 4y ago
        Oh, that's a good point – I personally never use my security key at untrusted computers, but I guess this could be a somewhat common use case. > If you assume there is never any malware on the host then you don't need the key at all—the host can store the secrets and handle the authentication on its own. True, a permanently plugged in authenticator is largely equivalent to just using a password manager (which also prevents against skimming, if used exclusively via autofill, never via copy/paste), but unlike a password mananger, it makes unsafe actions explicitly impossible for non-sophisticated users. I'd consider this a strong advantage. It also survives OS reinstalls, ransomware etc.

diggernet 4y ago

TacticalCoder has previously commented here (https://news.ycombinator.com/item?id=26844019 https://news.ycombinator.com/item?id=26844019) about the ability to set a specific seed on Ledger devices, so you can make a backup key that behaves identically to your main key.

lxgr 4y ago

This might be true for cryptocurrency transaction initiation, but in the WebAuthN model, what's the benefit of having a screen? The result of a WebAuthN challenge procedure is almost always a session cookie (TLS channel binding if you're really fancy), so the only thing that an authenticator could display on your screen is "do you want to authenticate as user x to website y", which arguably does not add that much value.

tialaramex 4y ago
The comment you're replying to is about cloning WebAuthn credentials. This is a delicate operation, because you are effectively cloning your entire identity. So yeah, a screen seems reasonable for that purpose.
nybble41 4y ago
> … so the only thing that an authenticator could display on your screen is "do you want to authenticate as user x to website y" … That is exactly why you want it. Consider, for a moment, that you have a key which is used to log in to your bank account and some other, much less critical site. Perhaps a GitHub account where you store some hobby projects. Without an unforgeable indication on the authenticator to show what you're logging in to, malware can wait until you're logging in to the second site, and thus expecting a prompt to use the authenticator, but actually trigger the authentication process for your bank off-screen. You tap the button or whatever on the authenticator thinking that you're logging in to your GitHub account but actually all your money is being siphoned off to who-knows-where. A key that signs whatever request is presented to it without any indication to the user of what the request actually was is dangerous.
- lxgr 4y ago
  If you have malware on your computer (that can compromise the browser), it can just wait until you actually log in to your bank and then grab the session cookie/proxy away your authentication. It's a different story if the operation you are confirming with a security key actually can be rendered on the display, e.g. "pay $100 to someshop.com" (as in SPC [1]). In that scenario, there is actually nothing to steal except for the signed message itself, which would be useless to anybody that's not someshop.com, but given that WebAuthN almost always just yields a session cookie, I don't really see the benefit. [1] https://www.w3.org/TR/secure-payment-confirmation/ https://www.w3.org/TR/secure-payment-confirmation/
  - nybble41 4y ago
    > If you have malware on your computer (that can compromise the browser), it can just wait until you actually log in to your bank and then grab the session cookie/proxy away your authentication. Sure, but you might never log in to your bank from this particular computer precisely because you don't trust it. But you think it's fine to log in to your hobby account since that doesn't store anything you really consider important. If you assume there is never any malware on the host then you don't need the key at all—the host can store the secrets and handle the authentication on its own.
    - lxgr 4y ago
      Oh, that's a good point – I personally never use my security key at untrusted computers, but I guess this could be a somewhat common use case. > If you assume there is never any malware on the host then you don't need the key at all—the host can store the secrets and handle the authentication on its own. True, a permanently plugged in authenticator is largely equivalent to just using a password manager (which also prevents against skimming, if used exclusively via autofill, never via copy/paste), but unlike a password mananger, it makes unsafe actions explicitly impossible for non-sophisticated users. I'd consider this a strong advantage. It also survives OS reinstalls, ransomware etc.