key safes

Russe11 · 14 February 2011 at 12:59PM

Biggles wrote: »

There are only [STRIKE]205[/STRIKE] 210 combinations.

oh so it does not have the numbers 1,2,3,4,5,6,7,8,9,0 then?

Biggles · 14 February 2011 at 1:01PM

Russe11 wrote: »

oh so it does not have the numbers 1,2,3,4,5,6,7,8,9,0 then?

It has exactly those numbers, each of which (see post #5) can be used only once. This narrows down the options considerably.

Russe11 · 14 February 2011 at 2:34PM

10C4

is this what your doing?

10*9*8*7/(4*3*2*1)

Russe11 · 14 February 2011 at 3:14PM

10!/(4!(10-4)!) 210

10!/(5!(10-5)!) 252

10!/(6!(10-6)!) 210

Doing that means theres as many combinations having 4 digits as there when you have 6 digits.

Permutations and combinations are different things, its order specific, doing the lottery with 10 balls in a bag and you pick 4 out, you being right in 1 in 210. It does not take into account that the order has to be correct.

The order has to be correct for a keysafe?

I could very well be wrong, it would go a long way to explaining where I am currently in life

Biggles · 14 February 2011 at 3:22PM

There are 10 buttons. If you have the right 4 pressed in, it can be opened. The order doesn't come into it, they are separate physical buttons (see picture on http://www.keysafe.co.uk/).

Hence if your selected code has more than 4 digits, nobody would be able to crack it in a month of Sundays, mainly because most of the time they would be guessing how many digits were involved.

Russe11 · 14 February 2011 at 3:33PM

Just to clarify if order is not important 4 digits is as secure as 6 digits, with 5 being little bit better.

Anyone that has a keysafe where the digits are not orderdependant might as well just keep the key under a random object in the garden, one of 252 object or more would be as secure.

Russe11 · 14 February 2011 at 3:37PM

Biggles wrote: »

Hence if your selected code has more than 4 digits, nobody would be able to crack it in a month of Sundays, mainly because most of the time they would be guessing how many digits were involved.

there are the same amount of combinations of 6 as there are 4, so its no more or less secure having either 4 digits or 6.

Russe11 · 14 February 2011 at 3:44PM

Or even more simply just don't push the opposite buttons.

its the same maths just which ones you press in for a 4 digit combination you leave unpressed for a 6 digit combination.

THE CONCLUSION IS IF YOU HAVE COMBINATION KEYSAFE, ITS NOT VERY SAFE.

Biggles · 14 February 2011 at 4:44PM

Russe11 wrote: »

there are the same amount of combinations of 6 as there are 4, so its no more or less secure having either 4 digits or 6.

Yes, but having failed to get in by running through the full set of 4-digit codes, will the theoretical burglar have time to start working his way through 5-, 6-, 7-, 8-, 9- & 10-digit codes? Or will he give up?

The key (er, literally) is in knowing how many digits there are. And it would be pretty unusual for him to start with anything other and 4-digit codes.

Biggles · 14 February 2011 at 4:46PM

Russe11 wrote: »

THE CONCLUSION IS IF YOU HAVE COMBINATION KEYSAFE, ITS NOT VERY SAFE.

I agree, but it meets a need, especially where someone, like my Mum, had maybe three different carers come each day. You don't want spare keys all over the place.

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