That's one way of looking at it. Note that you can easily extend it to multiple people holding multiple keys, so that a=b^c^d^e, etc.
My point was that encrypting a copyrighted work does not remove the copyright from it; the result is still copyright and not legally redistributable.
My point was that encrypting a copyrighted work does not remove the copyright from it; the result is still copyright and not legally redistributable.