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Comment by anfedorov | Hacker News Reader

> If you're using a password manager to have unique passwords for every site, what does TOTP 2FA even protect you against?

Sounds a little obvious to write it out, but it protects against someone stealing your password some way that the password manager / unique passwords doesn't protect you against. Using a PM decreases those risks significantly, mostly because how enormous the risks of password reuse and manual password entry are without one, but it certainly doesn't eliminate them entirely.

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It's not at all obvious to me, because 1Password passwords are stored in the exact same places that 1Password-managed TOTP codes are. You might as well just concatenate the TOTP secret to your password.

which is why I'm wary of using my password manager for OTP, and use a separate one. Not sure if it's too paranoid, but it doesn't make sense to me to keep the 2 in the same place.

There appear to be two points being conflated — 1/ 2FA via secrets stored on a separate device from your primary device with a PM provide more security than those stored on one device, and 2/ once you use a PM with unique password for every site, much of what OTP helps with for is already mitigated.

Both seem true, and what to do to protect yourself more depends on what kinds of attacks you're interested in stopping and at what costs. Personally, PM + U2F seems the highest-security, fastest-UI, easiest-UX by far — https://cloud.google.com/security-key/

Having a TOTP secret would protect against theft of credentials in transit. The TOTP is only valid once, so that credential exchange is only valid once. They wouldn't be able to create any additional login sessions with the information they've attacked. However, there's a good chance if they could see that they might also be able to see a lot of other information you're exchanging with that service.

It creates a race condition in transit - if they can use the code before you, then they win. I can intercept at the network level, but also via phishing attacks - there is no domain challenge or verification in TOTP.

I know having someone malicious get into your account multiple times vs once is likely worse, but its hard to quantify how much worse it is - and of course using that one login to change your 2FA setup would make them equivalently bad.

Not quite exactly "equivalently bad", since a user is more likely to notice a 2FA setup change than they are a phishing site's login error and then everything working as usual, but yeah, perhaps it's splitting hairs at that point.

If you're using 1p password for storing your passwords, then yeah, it would make sense to use something else for your TOTP.

This is the thing I struggle with: name a scenario where you would have your unique site password compromised but not have at least 1 valid 2FA code compromised at the same time.

The best answer I have for where TOTP can provide value: you can limit a potential attack to a single login.

I wanted to say you could stop someone doing MitM decryption due to timing (you use the 2FA code before they can), but if they're decrypting your session they can most likely just steal your session cookie which gets them what they need anyway.

Because you accidentally type your password for site A into the login for site B.

Someone “hacking” the 1Password web service

Logging in to a site on a public computer and the browser auto-remembers the password you typed

A border agent forcing you to log into a website (this scenario only works if you leave your second factor, which will most likely be your phone, at home)

Usually in a higher security environment, we'll make sure the authenticator is a separate device (phone or hard token) and expressly forbid having a soft token on the same device that has the password safe.

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