[SGVLUG] Security riddle

[Rae Yip]

Depends if your postal system uses DNSSEC or not. ;)

Seriously, the riddle has a better solution that doesn't involve
putting the locks inside an unlocked box. If you eliminate some of the
operations in the proposed solution, you'll arrive at the answer.

I can't claim any credit since I learned this one from a job interview.

-Rae.

On Mon, Nov 23, 2009 at 12:44 PM, Mike Rubel <mrubel at galcit.caltech.edu> wrote:
> Is there any worry about a "man in the middle" intercepting the original
> shipment and replacing your open lock with his own?  (Then replacing the
> recipient's lock in the return shipment, and so forth?)
>
>> Send the unlocked box with one of your locks. the recipient places his
>> lock
>> inside and locks the box with your lock. You unlock the box with your key,
>> put the item in the box and lock the box with his lock. he unlocks it with
>> his key.
>
>
>