Be careful...

[hammyma]

This is really the only place that I can tell this. From everyone else's viewpoint it must be very amusing.
I play alone, so when I noticed this http://www.screwfix.com/p/5-key-combina ... safe/77908 it seemed to have potential as a pervertable.

I'd previously used a http://www.screwfix.com/p/4-digit-brass ... 40mm/88823 and found that it was fairly easy to pick, using a digital micrometer (you do all have digital micrometers, don't you), to identify, in turn, which value each of the wheels is set to. So I figured that if anything went wrong, I'd just try the same technique.

You can see where this is heading, can't you.

The keysafe came with clear instructions on how to set the combination and I tried it out and made sure I had the procedure down pat. Then I set, and locked, it without looking at the combination. I reasoned that if I tried 100 different numbers each day, I should be out in under two months (statistics). Trying 100 each day lasted about a week and I was soon trying up to 1000 each day and before long I realised I'd gone from 0000 to 9999 and it hadn't opened.

It is always possible I'd missed one, somehow.

So I fetched the micrometer and it soon became apparent that this was not a winning strategy. The opening lever on the facia is made of plastic and quite flexible enough to hide the variations in manufacture that allow you to pick it.

I've now done 9999 back to 0000 and it still hasn't opened.

Did I forget to push the little lever into the right place when I closed it and it is just setting new combinations as I try them?

Does it need a few seconds with the right combination set before it will work and I am trying different values too fast?

Do I need to find my 3mm tungsten carbide burr (you do all have tungsten carbide burrs, don't you)
that will eat, slowly and inexorably, through steel?

Do I simply panic?

[Tom Allen]

(you do all have digital micrometers, don't you), to identify, in turn, which value each of the wheels is set to.

Do I need to find my 3mm tungsten carbide burr (you do all have tungsten carbide burrs, don't you)

:wave hand:

Ooh! ooh! I've got some!

Do I simply panic?

What kind of device do you have?

[hammyma]

Mentioned the device somewhere else... too hard to find the post, so: a bit like a Lori's tube, custom made out of aluminium with a stainless 'prong' for a PA. One of the CB?K devices works in a somewhat similar way. The prong is fastened with security screws that need a special Allen key (no relation ?) with a hole in the end. I may post a photo if I ever get it off (read puns into that according to language preferences).
But really, neither advice nor sympathy is expected, or deserved.

[mikecb]

You might try re-reading the instructions carefully to see if they have a note like "If you miskey the password, please wait xxx seconds before trying again". If it only has 10,000 combinations, a very good strategy would be to put a delay between allowable attempts.

mikecb

[Atone]

I think I would go the route of picking the lock on the device. If all you need is a security allen key then that should be pretty easy and inexpensive. Worst case you can order one on amazon for a couple of bucks. If you have a digital micrometer you probably also have a set of digital calipers, you could easily measure the screw head to determine the correct one to order if you don't want to buy a whole set.

-A

[Tom Allen]

I think I would go the route of picking the lock on the device. If all you need is a security allen key then that should be pretty easy and inexpensive. Worst case you can order one on amazon for a couple of bucks. If you have a digital micrometer you probably also have a set of digital calipers, you could easily measure the screw head to determine the correct one to order if you don't want to buy a whole set.

-A

:like:

[LockedUpNewb]

It's aluminum...................... a couple sharp blows with a sizable hammer ought to open it.

You're out some cash for destroying the thing, but at least you won't be locked up forever.

You could always drill holes in the side until you have a big enough hole to fish the key out with a small pair of hemostats or tweezers.

You're not REALLY trapped. You're just slightly inconvenienced for the time being. If you really want out - smash the thing into pieces with a hammer and recover your key.

[Locked by LRC]

I'd previously used a http://www.screwfix.com/p/4-digit-brass ... 40mm/88823 and found that it was fairly easy to pick, using a digital micrometer (you do all have digital micrometers, don't you), to identify, in turn, which value each of the wheels is set to.

I'm curious about your process. How does a mic tell you what the combination is?

[hammyma]

Picking a combination lock...
Assume there is something you can measure, like the hoop on a padlock. Assume that it is mass produced. Then there will be small differences in the manufacture and assembly of each wheel. Measure the 'gap' (eg, between the hoop and the body) when each wheel is in each position: 40 measurements. Note the extreme and set that wheel to that number. Repeat for the other three wheels: 30 measurements. Set the second wheel and so on. This depends on (a) imprecise manufacture (b) precise and consistent measurement, hence the need for a good digital micrometer (or calipers). Mine cost about 30 USD and reads to 10 microns. (My father's vernier calipers cost about 300 (in today's money) and read to one thou. Such is progress.)

In the films, you will see people cracking combination locks by touch/sound/etc: if they're that sensitive they'd probably make more money as brain surgeons; the tactile approach doesn't work for me.

And, yes, of course I can open the keysafe in about five minutes but (a) brute force lacks style and (b) it would spoil the story. Give me another few days and I'll not be worrying about style, believe it.

[hammyma]

Just to round this out: brute force and tungsten carbide won over style and micrometry. I still don't know why it didn't open when I tried all the combinations.

Musing on this, it really does show that security is defined more by the capability of attack rather than the strength of defence.