Based on these simples rules
;
- Six digits combinations maximum
- After 3 unsuccesful tries, locks up for 10 minutes
- According to Dave' captured traces;
- Accepted sequence of 2 # shows definitively different traces than any unaccepted sequences
- A 10 second delay between key presses allowed
- Print this chart with these sequences of tries
(It might be optimized, I don't know)
123456 678902 001122
030405 334455 667788
991098 876543 321314
151617 181924 252627
282920 353637 383930
344647 484940 424357
585950 516869 606562
797073 808471 957174
727596
- Grab traces of each key-press
- Mark the pair of digits that are accepted
- You should encounter 8 pauses of 10 minutes
So let's say that unbeknowst to you, the code is 766129
You see in your chart that these accepted sequences came up;
12 66 76 61 and 29
Revisiting the rules at the top, one can deduce easily
that the code cannot be anything else than 766129.
In a little more than 1 hour, it's cracked.
There is brute force
and there is smart brute force.