You want to send a valuable object to a friend securely. You have a box which can be fitted with multiple locks, and you have several locks and their corresponding keys. However, your friend does not have any keys to your locks, and if you send a key in an unlocked box, the key could be copied en route.
How can you send the object securely?
(In reply to
re(3): solution by ryan smith)
If we allow an interceptor to impersonate the friend in all actions and communications, I don't think there is a solution short of delivering the packet personally. (Or having the friend collect it himself, for the more lazy ones ;)
re(4): solution
