This is the discussion thread of my rail based combination lock in the community content.
http://starmadedock.net/content/combination-lock-the-only-secure-one.3032/
I present you a combination lock with an insane number of possible combinations, buildable in two versions:
One without any additional Logic, only using Buttons (Or Activation Modules) with lower security.
And one with a small counter logic that resets all states if the code was wrong.
It is based on the fact, that a button with a rail behind is able to change the direction of another rail.
For example:
Button1 has Rail1 next to it; Button2 - Rail2, and so on.
If now Rail1 faces in the direction we want, and all other face in the opposite direction, than we can chain up Button1 to Rail2; Button2 to Rail3, ...... and the last button to our output-rail.
Now if we press the buttons in the right order (1,2,.....Last) then the output-rail faces in the direction we want, in all other cases not.
Our door on rails now is able to open.
All we need now is a reset button.
The mathematical formula for a panel with 9 buttons and a code-length of 9 would be: (every button is only allowed once)
9!/(9!*0!) * 9!
For four digit code length:
9!(4!*5!)*4!
Because we have no indication if a code was invalid at the end of the sequence, one could crack this system (if code-length of 9) by pressing buttons 1 to 9, nine times in a row and then hit enter.
Because of this a code-length of 4 and 5 would be the optimum having 3.024 combinations. (Both with the same security)
Now if we add a simple counter that resets all rails after 9 digits, this attack would be no more possible, increasing the max code-length to 8 and 9 (both with the same security) with 362.880 combinations.
So I know my explanation isn't the best but i hope at least some of you got it.
If anyone finds out something to significantly reduce the combinations for a brute force attack, let me know it.
I will upload improvements over the time, stay tuned.
http://starmadedock.net/content/combination-lock-the-only-secure-one.3032/
I present you a combination lock with an insane number of possible combinations, buildable in two versions:
One without any additional Logic, only using Buttons (Or Activation Modules) with lower security.
And one with a small counter logic that resets all states if the code was wrong.
It is based on the fact, that a button with a rail behind is able to change the direction of another rail.
For example:
Button1 has Rail1 next to it; Button2 - Rail2, and so on.
If now Rail1 faces in the direction we want, and all other face in the opposite direction, than we can chain up Button1 to Rail2; Button2 to Rail3, ...... and the last button to our output-rail.
Now if we press the buttons in the right order (1,2,.....Last) then the output-rail faces in the direction we want, in all other cases not.
Our door on rails now is able to open.
All we need now is a reset button.
The mathematical formula for a panel with 9 buttons and a code-length of 9 would be: (every button is only allowed once)
9!/(9!*0!) * 9!
For four digit code length:
9!(4!*5!)*4!
Because we have no indication if a code was invalid at the end of the sequence, one could crack this system (if code-length of 9) by pressing buttons 1 to 9, nine times in a row and then hit enter.
Because of this a code-length of 4 and 5 would be the optimum having 3.024 combinations. (Both with the same security)
Now if we add a simple counter that resets all rails after 9 digits, this attack would be no more possible, increasing the max code-length to 8 and 9 (both with the same security) with 362.880 combinations.
So I know my explanation isn't the best but i hope at least some of you got it.
If anyone finds out something to significantly reduce the combinations for a brute force attack, let me know it.
I will upload improvements over the time, stay tuned.