AES-XTS VFS

[ncruces]

Fix #167.

Thank you, @ben-krieger!

[ben-krieger]

Behavior seems to be the same as before with fido-device-onboard/go-fdo#11, but I can't directly compare, since the pepper and sector size changed.

[ncruces]

@ben-krieger the fact that I merged this doesn't mean that it's final (even if I tag a release).
I'll mention in the release notes that this VFS is experimental, until you give final approval.

If security review on your end feels that anything should change, and that requires a compatibility break, we do it anyway.
Security review is kinda whole the point of this, and go-fdo the primary client.
There's little point in keeping compatibility with something that fails review and goes unused.

[ben-krieger]

@ben-krieger the fact that I merged this doesn't mean that it's final (even if I tag a release). I'll mention in the release notes that this VFS is experimental, until you give final approval.

If security review on your end feels that anything should change, and that requires a compatibility break, we do it anyway. Security review is kinda whole the point of this, and go-fdo the primary client. There's little point in keeping compatibility with something that fails review and goes unused.

I'm trying to get an informal review done now. But worst case, there will be another official review once we tag the first release of go-fdo, so I'll keep you updated.