Key 'storage' by abusing U2F devices

This is a proof of concept for abusing U2F devices and the cryptography they use to derive a stable secret.

If you're brave or reckless, you could use this technique to derive keys to encrypt your disk, or password database, or SSH keys.

See https://jbp.io/2015/11/23/abusing-u2f-to-store-keys/ for the background.

Usage

You need python-u2flib-host first: https://github.com/Yubico/python-u2flib-host

Then run python u2fkey.py enroll to set things up. This will print the key value and store state to data.json in the working directory.

Next, run python u2fkey.py auth to get the key value back.

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