andrel <a_l### [at] hotmailcom> wrote:
> I personally think doing it in hardware with nuts and bolts is more 
> impressive, but that may be just me.

  I suppose it's simply a question of cleverly allocating combinations
of pin assignments to locks and keys. I can imagine at least one simple
way of achieving a hierarchy of master keys with pin locks:

  In all locks, all pins have a cut for the highest-order master key,
as well as the secondary cut for the lock-specific key.

  The locks are divided into groups of locks (eg. on a per department
basis). All the locks in one group have the exact same secondary cut
for the first pin, but this secondary cut is different in different groups.
This way a master key for a specific group of locks uses the group-specific
setting for the first pin, and for the rest of the pins it uses the setting
for the highest-order master key. This way it can open all the locks in its
own group, but it can't open the locks of the other groups (the first pin
being different stops it).

  (If there are too many groups, using just one pin to differentiate between
them might not be enough, but in that case more pins can be used for this
purpose. The amount of combinations increases exponentially.)

  If each group should be further divided into smaller sub-groups, the
same technique can be used with the second pin, the third pin, etc.

  Then there's the reverse problem: All keys, including lock-specific ones,
should open a common lock (eg. the door leading to the entire department).
A lock-specific key should open, naturally, its own lock *and* the common
lock, but it nevertheless must not be a master key which could be used to
open your work pal's office. Obviously master keys should also open these
common locks as well. However, the lock should not be openable by a key
not related to the company at all.

  In other words, the situation is kind of a reversal: The common lock is
a "master lock": It should be openable by a group of keys, but not by any
keys outside that group.

  I have difficult time bending my mind into resolving how exactly it is
done, but I can perfectly imagine there's a simple way. Ingenuous, but simple.

-- 
                                                          - Warp

Post a reply to this message