From: technews@iitmax.iit.edu (Kevin Kadow)
Subject: Re: Security
Organization: Technology News, IIT, Chicago, IL
Date: Wed, 29 Jul 92 23:55:55 GMT

In article <9VPmoB2w165w@hacktic.nl> bill@hacktic.nl (Bill Squire) writes:
)flatline@eskimo.celestial.com (Flatline) writes:
)> 
)> yikes. this is scary. what is the exact technique used to open a master spin-
)> ter hole, make a master key, or otherwise open the locker? thanks. 
)> also, does anyone have a list of combos to be tried that would prob hit in th
)I haven't had a chance to talk to my friend in California about how he
)opens Master locks, but I have a few ideas, while not a minute tops, but
)still fast enough.  I will call or Email him and ask him to post or tell me
)what to post.  In the meantime, this should give some ideas:
)
)As I said in my orignal post, you need only try about every four
)combinations.  There is also the mechanism of the Master combination lock
)itself that gives away the last part of the combination.  By lightly
)tugging and turning the dial, you will quickly get the part of the
)combination. (try it on a lock you know)  Now that you have the last part,
)you have two more numbers to find.  Since the usable resolution of the
)Master lock is about four digits, there are ten possibilities arround the
)dial.  Now it should be obvious that there are at most 100 possible
)combinations to try, and at average they'll be 50, since the last part can
)be determined as above or just slowly turning the dial until it opens.  Now
)say you can do a combination test in five seconds (a beginner speed) you'll
)have the average Master lock in four minutes!  While not exactly "one
)minute tops" it won't be bad for a beginner!  As far as lists go,
)there are a few standard combinations master uses, but I don't really know
)who has it, but I've heard of it.  A crack list would look something like
)this:  00-00-NN, 00-04-NN, 00-08-NN,........36-28-NN, 36-32-NN, 36-36-NN.
)There are of course 100 combos on the list.  How this whole topic puts me
)back to my dreaded stupid Jr. High and Highschool days!
)
)                                                        Bill

With only 40 digits (10 positions) and 100 possible combinations, this looks
like a few seconds work for a electronic device.

Take a cheap (and fast) stepper motor, a solenoid (to test if the combination
was valid- you can't put constant pressure on the shackle [it locks the dial]
so the solenoid would have to push the shackle after each combo is dialed.

Considering the design of combination locks, there should be a way to
progressively test the combinations. Am I right in assuming:

99% of locks have 3 dials inside, each with _only_one_ "pin" and one or
more notches, one of which is deep enough to release the shackle?

If you can be sure that there is only one pin per dial, then it should be
possible to progressively test each comb. If you turn the lock 2 turns to
"clear" it, then you know that the pins are lined up

-- 
                                "forty-two"
                                             - Douglas Adams

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