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?

First of all, the problem is not specific as to the number of locks the box may contain, it just states "multiple" meaning more than one. Then,assuming that you have several locks and their corresponding keys does not necessarily mean that all the locks you put on the box will require a key. So the logical answer would be to assign one of the multiple locks a combination in lieu of a key and the other locks will contain the keys inside of the locked box with the combination known only to the sender and the recipient. The only lock that is securing the box is that of the combination lock. Once the combination opens the box, the other keys can be removed. So, the only real security, unbeknownst to any mail carrier would be that of the combination lock since the remaining key locks could not be tested since the box could not be opened anyhow.

Posted by Steve on 2003-12-17 00:13:06