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Correct me if I’m wrong but U2F tokens are an antidote to TOTP seeds being leaked, right?

Edit: some reading: https://en.m.wikipedia.org/wiki/Universal_2nd_Factor I have the advantages and disadvantages section a read and I believe I got it right. The one major disadvantage I’ve read about is that there is no backup. At a place I worked, we registered two keys and kept one as a backup. It seemed to work okay.

Also this: https://www.yubico.com/blog/otp-vs-u2f-strong-to-stronger/

On OTP:

> The remaining issues, however, are phishing and man-in-the-middle attacks, the most infamous assaults that defeat OTP technology. The theory is quite simple: the hacker sets up a fake website designed to trick visitors into submitting their credentials. When a user falls into the trap and enters his information (user name, password, and even his one-time password), it is immediately intercepted by the hacker and used to access the victim’s account.

Later, on FIDO U2F:

> Real-time challenge-response schemes like U2F address OTP vulnerabilities such as phishing and various forms of man-in-the-middle attacks. As the legitimate server is issuing the challenge, if a rogue site or middle-man manipulates the flow, the server will detect an abnormality in the response and deny the transaction.



Technically yes, but from memory, your U2F public key would be leaked. Thus depending on your threat model you may still want to rotate U2F keys.


I thought ‘public’ means it can be shared widely without there being a risk to the private key. What threat model would consider it a risk to have a public key exposed?


Identity/privacy: de-anonymizing accounts reusing the same public key.


U2F generates a new keypair for each origin. Public keys are not re-used.


Think of it as an HSM. It will most likely prevent the TOTP seed from being leaked but that doesn’t implicitly keep you safe.


Sorry, I was asking about U2F as an alternative to TOTP and not a method of implementing such. If I’m not mistaken that was unclear on my part and you were led to interpret what I said a different way than I intended.




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