So this is a place where for optimal outcome it would make sense to:
- add a short comment in source code where the fact that the "external key authenticate" method is actually only called through sc_pin_cmd and thus is expected to behave as a  PIN method (so that looking at it and understanding some without first reading all the other code in context would be possible)
- rebase the useless "recover line" and "add back copyright" into a single commit
- write a meaningful commit message to that single commit
- fire up a new pull request.