The Perfect Lock Can It Be Picked?

[Legion303]

Femurat gave you the correct answer for both scenarios in the second post:

No, if the perfect lock exist, it couldn't be SPPed. Unfortunately such a lock can't exist.

-steve

[3-in-1]

I know I posted one scenario. What is the second one?

[unjust]

the very geometry of a traditional pin tumbler inherently provides for the exploits that allow it to be theoretically spp'd.

does that mean that i could pick one built to the most exacting standards practical? probably not, i'm more student of theory than ultra fine finger finesse.

in order for the pins to pass the shear line, their mating surfaces must either be rounded enough to accommodate the arc segment of the core that they cross, or they will not permit the core to turn at all. (typically this is roughed in as a champhered edge) because of the tolerance necessary for them to slide, it must be possible to rotate the core a small amount before it is actually prevented from turning and opening the lock.

if the pins are rounded, then their edges will not immediately meet with the top pin and the bible when the core is turned. as they must be somewhat flat to actually bind up and lock the lock that flat surface can be used to catch on the differ between the core and bible's alignment.

given that there are people who can actually sculpt the lead on the tip of a pencil, and that a pin tumbler must be somewhat vulnerable in order to function i will posit that humanity possesses the skills to spp a "perfect" pin tumbler.

all that said, i often find that newer better quality pin tumblers are easier to spp than older ones with looser tolerances. the looser locks seem (to me) to be faster to open overall though via a rake type attack.

[3-in-1]

Yes, I have seen the pencil sculptures. Amazing. You have brought up a point that by necessity contributes to picking. Theoretically both bottom and top could be shaped with same arc as the lock itself. In the MIT flat lock example, holding the same line is possible and and even practical. If the pins were incapable of rotating in their chambers this could also be done in cylindrical locks. But they aren't held in place, so by necessity the pins must have a bevel of some sort to ensure functionality. This greatly increases the shear line, improving the chances of landing on it. This would be called a design consideration by the maker and design flaw by the would be picker. I think the somewhat flat area is to try to keep the shearline as small as possible. A crown meeting a crown would increase it even more so. I think the flats would also increase the surface contact area resulting in better wear characteristics. And I am thinking that possibly it is the sharp edges in new locks than eventually get worn down in use, that contributes to their being picked more easily. Any other ideas?

[FarmerFreak]

Theoretically both bottom and top could be shaped with same arc as the lock itself.

Yes, they can. And as you pointed out all you'd have to do to allow that to happen would be to prevent the pin from rotating. DOM dimple locks actually do that. viewtopic.php?t=11337

[unjust]

You wouldn't have to prevent rotation, merely allow for reallignment ala a biaxial key and key pin.

[Amaranthfox]

Since the pins would still bind, it may be possible to pick a perfect lock. Even if all of the pins bind at the same time, they will still bind. As each pin reaches the shear line, the pressure would deform the other pins very slightly, but it would be so little that it would be undetectable. However, if we can assume a perfect lock is possible, can we also assume the perfect picker exists? If someone were able to detect the movement from the deformation of the pins, and we could also assume that the movement from the other pins deforming more was enough movement to make the picked pin catch, then it should still be possible to SPP the lock.
So from a practical standpoint, no, the perfect lock cannot be SPP'd. But with the assumption of the perfectly fitted pin holes and the perfect picker, it should technically be possible.

[unjust]

i disagree. a perfect lock could be spp'd w/o needing to feel deformation. technique would change a bit, rather than seeing if another pin bound if they all bound simultaneously (which due to physics they cant) you merely see if the pin passes the shear line as the key pin will fall after that pinstack is at the shear line.

[3-in-1]

First off I want to thank those of you who have entered into this thought experiment. I have now found online where my totally functional "perfect" lock and the non functional "perfect" lock mentioned by others here, have both been described. I think Matt Blaze called it the "ideal" lock, and maybe that choice of terminology would have prevented some of you from repeating what I found on TOLG. Anyway it all goes back to when I was making 2-in-1 picks for safe lever keylocks. One of the few makers that did not use false gating was Steelage of India. These were either 8 or 9 lever locks I don't remember. I would always make a cutaway to study the action as the lock was picked and I found that it was not possible to just find a binding lever and set it. And that the amount of binding pressure used was of great importance. Not until I kicked up the pressure considerably was I able to even pick the lock. Increasing it even more sped up the process. Since it is only recently that I have started to study pin tumbler locks I cannot say just how much of the information gained in studying lever tumbler will transfer. But I do know for a fact that some of it will. For example, I have found that sometimes a pin will have a little initial bind but loose it as it is pushed up further. Once this bind is released other pin(s) will bind more. This first pin may or may not set. If is pushed all the way up and released from its highest position, it might slam right back down, effectively loosing any gain of binding pressure on the other pins. Oh, and Unjust, a bottom or key pin will fall freely even if the binding top pin is not pushed all the way to the shear line. But thank you for your continued efforts in thinking this thing out.

[unjust]

gah, you're right, i'll note in my defense that i was absurdly not awake in composing that bit. the rest still holds though that it's possible, just dealing with shifting method as tolerances become more tight in pin tumblers.