On 2012-10-08, Jon Elson wrote:
Ro Grrr wrote:
I'm getting a DIEBOLD FILE SAFE that is about 5 feet tall and 3 feet
wide, double doors. Its locked and there's no combination so I'm
probably giong to have to drill the door to get into the combination
lock.
Do you know if it is a 3-number combination or 5? If 3 numbers, I'd
just try them all, it is probably a lot faster than trying to drill
a good safe, even if you knew the exact spot.
I've not seen a photo of his, nor much of a description other
than "DIEBOLD" and "two-door", but the safes which the Government uses
(at least at army R&D labs, where at least medium classification levels
are common) use combination locks with 100 numbers on the dial, and
three setable numbers, plus a final zero. And depending on which flavor
of locks were used, you either have to hold the dial at that final zero,
and turn a small central bar and then rotate it a bit more -- and
doing that disturbs the previously set discs, so you have to go through
the full dial operation again to try the next. And then you have to try
the handle to see whether it really withdrew the bolt -- though you can
probably tell by feel once familiar with the lock.
Assuming that all three numbers could be any of the 100, that
leaves 1,000,000 combinations to try. Normally, you are advised to
avoid number near zero (especially on the last one, but assuming that
you avoid 98 through 02, that still leaves 857,375 combinations to try.
(And also consecutive numbers should not be too close to each other,
which reduces the count a bit more, but not really enough. :-)
Let's assume that my 857,375 count is reasonable, and that it
takes about 30 seconds to dial a combination. If you have to try every
combination, that calculates to about 297 days of 24 hours a day trials.
Drop it back to 8 hours per day (so you can get other things done), and
that becomes 893 days -- or well on your way to three years. :-)
And this is not counting some way to keep records of what has
been tried. I would advise a computer with a toe-operated switch to
increment the numbers -- and with battery backup so you don't lose your
count.
Since the combination is likely to be anywhere in the range, you
might write a program to generate random numbers, and keep track of
which ones have already been tried. You might include statistics to
tell you what percentage of the way through the choices you are -- just
to keep you depressed until you are a couple of years into the project.
It is not quite as easy as holding a cheap combination padlock
in your hand and twiddling while applying strain to the hasp, which is
likely to open it without serious concentration in a few minutes. :-)
Oh yes -- this is mounted on something the size of a couple of
file cabinets side by side, with thick walls filled with concrete or
asbestos/concrete mix to maximize the insulation during a fire, so you
can't just bring it over to where you sit down -- you have to go to it,
and set up as comfortable a chair as possible which allows you to reach
the dial and manipulate it for hours at a time.
You *will* miss-dial some, so you need a way to tell the
computer to try that one again (perhaps just by not tapping your toe on
the switch) -- *if* you realize that you have misdialed it. Towards the
end of the seventh hour, you probably won't. :-)
Enjoy,
DoN.
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