There are a number of questions on this site about how/can you use a U2F key to encrypt something. The main problems with doing this are that U2F keys were designed for authentication, so all they can do is sign data. We could try using this signature as a key (after passing it through a KDF), except that their signatures incorporate randomness, and are different every time when signing the same data.

But this blog post talks about one way to do it. Now my curiosity is piqued, and I'd like to know whether this would work. (Or at least some other viewpoints)

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    $\begingroup$ Welcome to crypto.stackexchange - I am finding it difficult to discern what is being asked here. The first sentence says that the main problem with using a U2F key to encrypt anything is that the signatures are randomized. It begins by talking about encryption, but the problem is somehow related to signatures? But then you link to something that apparently does what you're interested in. But then the next sentence after that is whether or not it's possible. Can you use the edit link to re-formulate your question? Please clearly state what you have, what the goal is, and what the concerns are. $\endgroup$ – Ella Rose Jun 13 '19 at 14:08
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    $\begingroup$ It sounds like maybe the question is: Is this method, which is demonstrated to technically function in the sense that it gives back the correct answer when executed, actually a secure way to encrypt? $\endgroup$ – Squeamish Ossifrage Jun 14 '19 at 3:01
  • $\begingroup$ Correct, I'm sure you could get this to technically function, but I've no idea if its secure, and that's what I'm curious about. $\endgroup$ – JvH Jun 14 '19 at 8:02

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