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by ulrikrasmussen 144 days ago
No, the defining characteristic of a password is also how it is used: it is communicated in the clear to the verifier, thus revealing it to eavesdroppers. It is highly non-trivial to clone the knowledge in someone's brain if they never openly communicate the mTOTP secret but only do the computations in their head.
2 comments
swiftcoder 144 days ago
> No, the defining characteristic of a password is also how it is used: it is communicated in the clear to the verifier

This is only true if the verifier lives on your local terminal - otherwise we use an encrypted channel to transmit to the verifier, or do the exactly same type of timed-salted-hash scheme used here to transmit without revealing the password.

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ulrikrasmussen 144 days ago
The thing is that you are sometimes tricked into giving the password to someone who is posing as the verifier.
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crote 144 days ago
Not true. There are lots of authentication schemes where the plaintext password is never communicated. This becomes rather crucial when the client doesn't know for sure yet what the identity of the other side is. See for example wifi encryption.

Cloning the knowledge in someone's brain is fairly easy. You just need a wrench.

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ulrikrasmussen 144 days ago
Yes, but that is not how passwords work since the protocol for proving knowledge is that you enter it into the HTML form served by the party claiming to be the verifier.

If we are talking rubber-hose cryptography then a physical hardware token is just an insecure as a brain. Most people are not hacked via wrenches.

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crote 143 days ago
In other words: it's how passwords work on websites. Because it's usually good enough, as the only thing you are protecting is access to the server on the other side, and the pipe to that is already encrypted with TLS.

But this isn't a hard requirement. See Protonmail as a counterexample. And again, wifi authentication. I reckon debit card PINs as well.

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