29 Jul 04
You want to send a valuable object to a friend. You have a box which is more than large enough to contain the object. You have several locks with keys. The box has a locking ring which is more than large enough to have a lock attached. But your friend does not have the key to any lock that you have. Note that you cannot send a key in an unlocked box, since it might be copied. How would it possible to send the object?
-Ray.
29 Jul 04
1 edit
Originally posted by rgoudieMay I assume that my friend is also equipped with a box,
You want to send a valuable object to a friend. You have a box which is more than large enough to contain the object. You have several locks with keys. The box has a locking ring which is more than large enough to have a lock attached. But ...[text shortened]... ht be copied. How would it possible to send the object?
-Ray.
and his own set of keys and locks?
Dr. Cribs
30 Jul 04
1 edit
Originally posted by CribsI'll reveal this much:
May I assume that my friend is also equipped with a box,
and his own set of keys and locks?
Dr. Cribs
Your friend does not need another box.
Your friend may very well possess another lock with keys.
I'll further add that the priority here is to send the object securely over and above any other consideration.
-Ray.
30 Jul 04
1 edit
Originally posted by rgoudiePretty Good Privacy is based on the solution to this problem then.
I'll reveal this much:
Your friend does [b]not need another box.
Your friend may very well possess another lock with keys.
-Ray.
[/b]
Does that suffice as an answer, of shall I explain further?
Dr. Cribs
30 Jul 04
Originally posted by CribsThis is technically another clue. 🙂
You don't have a solution based on the friend not having
his own locks and keys, do you? I'm sure the computer
security world would love to know it, if you did.
Dr. Cribs
The solution does not involve the friend not having their own lock and key.
-Ray.
30 Jul 04
Originally posted by CribsCome on, Cribs, I know you can do it. A pimp gotta keep his mind sharp if he's gonna keep track of his bizness.
EDIT: Scratch all that nonsense. I didn't notice the
double negative in your sentence.
Here's a recap of the criteria:
He wants to send the object securely, which means that the box must have a lock on it.
He has at least one lock and key, but the recipient does not possess a key for the lock.
The recipient does possess their own lock and key.
Anything else goes. How does he get the object to the recipient securely? You may have to get lateral on this puzzle.
-Ray.
30 Jul 04
1 edit
Originally posted by rgoudiePGP's foundation is the answer. I tried replying to your clue, after I misread it,
Come on, Cribs, I know you can do it. A pimp gotta keep his mind sharp if he's gonna keep track of his bizness.
Here's a recap of the criteria:
He wants to send the object securely, which means that the box must have a lock on it. ...[text shortened]... securely? You may have to get lateral on this puzzle.
-Ray.
because I thought you said it could be done without the friend
having his own lock/key pair. I explained why that was impossible,
and then noticed that I misread what you wrote.
So, I do know the solution, but I won't detail it here
until others take a swing at it, because it is a pretty
interesting problem.
Dr. Cribs
30 Jul 04
1 edit
Originally posted by bbarrI must admit this as a plausible solution, but not the particular solution that I am looking for, How about if I add these two extra constraints:
Have your friend send you his lock. Have your friend keep the key to this lock. Use this lock to lock the box you want to send. Send the box to your friend.
No lock may be sent unless it is properly locked shut.
No keys may be sent at all at any time.
-Ray.
30 Jul 04
1 edit
Originally posted by rgoudieThese constraints together with your original ones make this
I must admit this as a plausible solution, but not the particular solution that I am looking for, How about if I add these two extra constraints:
No lock may be sent unless it is properly locked shut.
No keys may be sent at all at any time.
-Ray.
problem impossible.
Bbarr's solution is what I had in mind. That is the essence
of public key encryption, which is more or less the state of
the art in electronic security. If your newly stated problem
had a solution, it would be a major breakthrough in that field
and you could earn untold fortunes on it. But it doesn't,
unless you have stated it wrong, or unless I am misunderstanding it.
Your first new constraint is the killer. Any new security methods based
on keys always must address the "key distribution problem," and
your problem specifically disallows this aspect to be addressed, since
an open lock is essentially analogous to a "public key".
Dr. Cribs
30 Jul 04
1 edit
Originally posted by CribsThe solution is straightforward if you think outside the box (pun unintended).
These constraints together with your original ones make this
problem impossible.
Bbarr's solution is what I had in mind. That is the essence
of public key encryption, which is more or less the state of
the art in electronic security. ...[text shortened]... stated it wrong, or unless I am misunderstanding it.
Dr. Cribs
-Ray.
30 Jul 04
1 edit
Originally posted by rgoudieWell, there is the degenerate solution that you just
The solution is straightforward if you think outside the box (pun unintended).
-Ray.
physically hand the valuable item to your friend.
That meets all of the constraints, unless your notion
of "send" disallows this. If that is that case then you
should also not be able to physically hand over locks
and keys, and I maintain that your new problem has
no solution.
Dr. Cribs