a final word on masterlocks?

[gnoff]

I am trying to write a paper summerizing the information on mathematically cracking a masterlock. Some of the papers out there disagree about the number that you use to derive the first and second digits after mecanically decifering the last.
Some put the "dividor" at 4, meaning that if the final number of the lock was a 19, then the first digit is derived by dividing 19 by four, and taking the remainder as the digit (adding the numbmer 4 to each)
final-19
first possible- 3,7,11,15,19,23,27,31,35,39

however, other papers say that the dividor should be set at five,which means that if
final-19
first possible- 4,8,12,16,20,24,28,32,36,40

then the second digit comes around (by adding or subtracting 2? from each number)
final-19
first possible- 3,7,11,15,19,23,27,31,35,39
second possible- 5,9,13,17,21,25,29,32,27,1
or
final-19
first possible- 4,8,12,16,20,24,28,32,36,40
second possible-6,10,14,18,22,26,30,34,38,2

the lock i was useing told me the combination was 16-2-19, which means that the second set of numbers was correct, or more accurate at least, than the first.



in short, do you take the remainder of the final digit divided by 5, or by 4?

[keysman]

[quote="gnoff"]
the lock i was useing told me the combination was 16-2-19, which means that the second set of numbers was correct, or more accurate at least, than the first.

[/quote]

I haven't checked every master padlock so my info may not be right

But... they used to have all even numbers or all odd numbers in the combo. Never mixed.
Check your combination .. it should open +- .5 number or slightly more

That may have changed with currently manufactured locks

[gnoff]

ok, thanks ill check today

[Gordon Airporte]

I thought I heard, and I can't back this up, that they'd changed their system at some point - so it might be that both algorithms are correct, just for different series of locks.
I wrote a script for this at some point and it uses the mod 4 method, which came up with the exact combo for the only lock I could get my hands on. Still, there's a good chance that because of the loose requirements for hitting the numbers, both systems will generate a working combination (i.e. 15-1-19).

[gnoff]

ya, it works even if i get like 2/3 of the way past the number, so i guess using either the 4 or 5 dividor works fine,

on a side note, i found that if you take the 12 stickies turning one way, then find the other stickies going the other, the pairs of stickies will be ofset by 1 digit for around 5 numbers, narrowing down choices, it worked for my lock, can someone else verify with another?
ex...
Turning right
0,2,4,7,12,15,17,23,27,31,35,37
Turning left
1,2,5,9,13,15,19,22,24,30,33,39
pairs would be
0/1 2/2 4/5 12/13 22/23 30/31

so instead of 10 first digits and 10 second digits, you get 5 that can go either way (25 combos enstead of 100)
this worked for my lock, but it could just be a fluke

[Fah_Cue]

so i am right in saying i need to know the last digit to unlock it

[dwkbb]

The method of calculating the first and second numbers I have seen and seems to work on most of the Master locks I have does involve dividing the third number by 4 and subtracting the result from the third number. For example, 19 / 4 = 16, then 19-16=3. Add 4 to each subsequent number : 3, 7, 11, 15, 19, ect. Add 2 to each number to determine the possible second numbers: 5, 9, 13, 17, 21, ect. It is my understanding that all three numbers must be odd or even. This may not apply to all Master locks, but it has worked for most of the locks I have.

[gnoff]

so i am right in saying i need to know the last digit to unlock it

yes, you absolutly need to find the last digit first, using the 12sticking method, throwing out half digits and digits ending in the same ones value.

and dwkbb, that is the method that i have used in the past, but i think that the new method works better, as i got the same combination using a pool of 25 possible combos, rather than the traditional 100.

however, this could just be my lock that i got lucky with the numbers with, i am going to try to buy some masterlocks to practice cracking, but can anyone else use my method to open theirs?

[kstoerz]

The modulus technique works for the 15+ year old master padlock I have on hand. I used the system described in detail here and wrote a small PHP script to fill in all the possible combinations. If you can correctly determine the last number of the combination, this method appears to get you the correct combo mixed somewhere within 99 incorrect ones. Try the script for yourself, just change the number in the URL to the number of the lock's last digit:

http://basementfreaks.com/members/karl/master.php?n=38

This script uses a modulus value of 4 (as opposed to 5, debated a bit above) and seems to work. I tried changing it to use 5, and then it didn't even get close to the correct combo.

[inbeforyou]

i read sum where that if you slowly turn the lock and pull lightly, enough to hear/ feel the clicks, it will stop at a number, add this number with 5. the second number is found like wise, first spin the dial a few, then as you pass the first number start to pull and slow down, so you can hear/feel the clicks, it again should stop, this time the number. the third number, well you have time to quickly go threw an try them all after turning the dial correctly to the first 2 numbers, leaving you just putting the third to open.... sry i cant conferm it, but when tried i didnt have time to go for the 3rd number. the first 2 steps sounded/feeled like they worked though.


but remember, ill be in my locker first.

[illusion]

this methord is used with brief-case locks, or sessame locks.

You have the gyst of it though, well done

there is also a tool which helps

[DarkCloud]

Hi i have a master combo lock and I noticed that even when i hit a number to the right or left it still opens and although i have read many theories on working out the numbers from the last by using a specific formula which gives 64 combos rather than 100, i was wondering if it was possible to use the same combo for two locks which might have combinations that are very close to each others. this would narrow down the number of combo you would need to try. 40 x 64 = 2560 so if you halved that number you would only have 1280 combos to try.

Also i had thought of trying to design a mechanical device to spin the dial to all possible combos and "automatically" open the lock.
i had thought it could work like a drill in the way that it would spin one way then another until it had found the right one. this would be difficult to build but i'm sure it could be done.

[Gordon Airporte]

Hi i have a master combo lock and I noticed that even when i hit a number to the right or left it still opens

Yes, they are a little sloppy and they could easily be made tighter if they wanted. As for the combo generating algorithms - the one I'm familiar with (and I think there's only one) doesn't produce a list that could be shortened my taking the slop in to account. It has a distance of 4 between try numbers in a given position and the range due to the slop in the mehanism is closer to 2 or 3.
Also: each lock can be opened both foreward and backwards. There's a second combination you can use if you start dialing it ccw instead of cw like normal.

Also i had thought of trying to design a mechanical device to spin the dial to all possible combos and "automatically" open the lock.
i had thought it could work like a drill in the way that it would spin one way then another until it had found the right one. this would be difficult to build but i'm sure it could be done.

Such devices exist for safes, but they would be kind of silly for combo locks.
[/quote]

[DarkCloud]

i guess you're right i just thought that with combos like 4/10/16 and 5/11/17
you could try one and open a lock designed for the other and what if you the combo lock had 6/12/18 and you tried 5/11/17?
It would usually open and so you would only have to try every second combo...
as for the device, i was thinking something along the lines of a drill that would change the direction and if it were altered so it could be programmed (i.e chip) it could be applied to future locks.
on average it takes most people about 3.8 seconds to open their own and a drill takes just over 1 second, you could run through the combos in about twenty minutes.