Opening/removing SUPRA key-safe.

[David Chapman]

My son has just moved into a new (old) house and found a (locked) SUPRA key-safe attached to the side wall. This is the grey-box type that has two vertical rows of five mechanical push buttons (numbered 1 to 10) on it along with OPEN and CLOSE sliders. It's absolutely no use to him locked so he'd like to be able to open it or, if that is not possible, just to remove it from the wall without seriously damaging the brickwork to which it is attached. The previous owner of the house died so it's not possible to ask her the key combination.

Apart from the 'brutality with extreme prejudice' approach with a very large hammer, can anyone suggest a better way to open or remove it? Can anyone explain how this particular SUPRA key-safe is normally opened when the correct code is known? How many digits need to be entered, and how should the sliders be used? Is there a User Manual for it?

I suppose he could try entering all of the combinations one after the other but I doubt that he's got the patience in view of all of the other jobs that need to be done.

Many TIA - Dave

[Andrew Mawson]

without

previous

Angle grinder shouldn't take too long to cut a hole - it's probably only stout mild steel plate

AWEM

[Tanner-'op]

Dave,

A suggestion. We used one of then when my disabled father was alive to allow the social services/cleaners access to his property - it may be worth your while contacting them as this could be the case here - or possibly his neighbours.

As a matter of interest, if as suggested by Andrew, you decide to cut it off the wall, the steel in my father's old box tapers from around an 1/8" at the 'door' end to a 1/4" at the 'wall' end with a 1/4" base thickness (I've just checked it to see if there was an engineers code there [there's not] and the number of different combinations of numbers is quite large)

Tanner-'op

[John Stumbles]

Human factors: it probably wasn't the previous owner the thing was intended for but social services etc. If you can find out who was looking after him/her they may have the number on record. Maybe even the neighbours know it?

Otherwise try brute-forcing it in the cryptographic sense: if it's like the one our neighbour had (which I just opened and removed for the painters doing up the house for its new occupants!) it doesn't matter which order the numbers are entered in so 1234 is the same as 4321 etc - that reduces your search space. There can't be 2 digits the same so you can't have say 1233. And the mfrs recommend choosing 4 digits. I leave it as an exercise to the more numerate readers to work out how many combinations it is (1234, 1235, 1236, 1237, 1238, 1239, 2345, 2346,

2347, 2348, 2349, 3456, 3457, 3458, 3459 ...) but it's possibly less than the hassle of attacking it with an angle grinder and/or making good damaged brickwork.

[John Stumbles]

As I say, on our neighbours one the mfrs recommended setting it to 4 digits but 3 or 5 or possibly even 2 or 6 digits could be set. Most of these sorts of things have a clear or reset button to un-press any buttons you've already pressed, and once you've pressed your choice another device to (try to) open the lock. On our neighbours it was spring loaded so after you'd opened it with the correct combo and let go of the opening latch you had to enter the combo again to lock it - grrr!

As I said in my earlier message there aren't as many distinct combinations as one might think. Maybe offer a prize for whoever cracks it and invite in the street?!

[Tanner-'op]

No thanks John,

I once forgot my key to get into my father's house - but I thought that's no problem, I'll open the keysafe - ha!

I'd also forgotten the combination of that as well (a 5 digit one) and spent

40 minutes trying to wangle the damn thing before giving up and walking the half mile back to my house for his door key (and also writing down the combination of the safe to go in my wallet).

And I hate walking! :-(

Tanner-'op

[Andy Champ]

If I have my numbers right, there are 10 choices for the 1st digit, 9 for the 2nd, and so on so that 10x9x8x7, but as it doesn't matter what order you put them in you have to reduce that by 4x3x2x1 so 210 combinations. That's scarily few...

Andy

[Dave Liquorice]

Others seem to think they are steel, but the ones I see on the web look more like diecast zinc. Try forcing the cover with a cold chisel and lump hammer. Diecast will give up moderately easyly steel might bend a bit.

Try google... I found the instructions very quickly.

And another hit:

"All KeySafes are made from Zinc Alloy and come with a 24 month guarantee."

[The Medway Handyman]

Assuming numbers can be used more than once and all 10 numbers are used, thats 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x 10 possible combinations if my maths are right. Well over 3 million possibles.

Angle grinder!

[The Medway Handyman]

Most combination locks/safes allow you to use numbers more than once. 4 numbers mean 10,000 possible combinations.

[Bill]

In message , The Medway Handyman writes

A poor assumption if it is a "cheap" lock, certainly a lot of door locks similar to the type shown below do not mind what order you input the numbers. Also a tip with any lock like this is "keep ALL the buttons clean" I have opened quite a few by looking to see which ones are clean, ie used, and those that are dirty, ie not used.

?productId=35131&imageNo=null&ts=99144

[OG]

These are the mechanical ones you may see on internal doors in offices. Hit the right 4 buttons and turn the knob. It doesn't matter which order you hit the buttons.

[Matty F]

Trying the cleanest keys first would be a good idea.

Otherwise, assuming that each key can be used once, there are 1023 combinations. I'd say 4 keys used is most likely, so that's 210 combinations. I have opened locked briefcases bought at jumble sales in minutes by trying all combinations!

Keys Combinations

1 10 2 45 3 120 4 210 5 252 6 210 7 120 8 45 9 10 10 1 [duh!] total 1023

[Peter Crosland]

(X to the power X+1) -1 where X is the number of digits and number can be used more than once. So a five digit combination number has 15624 permutations and an eight digit combination has 134,217,727 possibilities. I was always told my "O" level maths would be useful some day assuming I have not screwed up!

Peter Crosland

[dennis]

Except mine is set to six digits to press so you will never find it. You can change the number of digits to press on most mechanical door locks, but not on the supra wall safes AFAIK.

[dennis]

The same applies to burglar alarm panels, you can see which digits people use on a lot of panels, either by the dirt or by the depressions in the membranes.. best to change the code so it doesn't happen.

[dennis]

You don't usually need to do that.. just put slight pressure on the bit you slide across.. find the loosest wheel and rotate it until you feel the knob move a bit,.. repeat with the next wheel. Takes a few seconds in most cases.

You could tell I worked for Chubb for a while if you saw how easily I can open desks and filing cabinets. I used to demonstrate how to do it with a spoon and a paper clip.

The best one was when someone came around trying to borrow car keys as he had locked his in the boot. I told him he was wasting his time as he wouldn't open it with another key, however he was absolutely amazed when I picked up a tea spoon and opened it in about two seconds.

Just as well I am not criminally minded. 8-)

[dennis]

Logic may be a bit wrong though.. with many of these mechanical locks you can have variable length numbers.. so its one from ten (or more as some have letters too) + two from n + three from n, etc.

It takes time as the damn things are so hard to actually press and then try, that is the principle behind them, if it were quick to enter the code and try a combination lock would be useless.

They should not be used where anyone can spend a long time unobserved as that is just asking for trouble.

For example, fitting one to the outside door on a porch and leaving the main door unlocked is a lot more secure than fitting one to the main door and leaving the porch unlocked. All a crim has to do is enter the porch and pin a curtain to the porch door and he can take as long as he wants to open the main door without anyone seeing him.

My favorite would be to knick a potted tree from somewhere and plonk it outside someone's house in the night. Then you go back and work behind the tree hidden from view. Most neighbours just wouldn't notice.

[John]

I believe that some mechanical locks just require the number to match the total of the code. eg: a code of 1234, could be openned with 5311

[dennis]

I can't imagine how (or why) you would design such a mechanism. It would be like a mechanical adding machine and they are complex.