Possible simple defeat for bumping?

[digital_blue]

Ok, for starters, this is so stupidly simple, I'm pretty sure someone must have brought this up already and I just missed it. So, as a response to this topic, I will accept all the "Search n00b!" replies you care to dish.

However, I was thinking tonight about bumping, and it occurred to me that this might work, so after some very preliminary testing, all I can say is that it appears to defeat bumping, or at least hinder it greatly.

Tonight I took one pin stack out of a lock, and replaced it with nothing more than a 9-cut key pin. No spring, no driver pin. My theory was that with nothing else touching the key pin, it would circumvent the "Newton's Cradle" principle, causing the key pin to jump up with the strike from the bump key.

And low and behold, it seems to work nicely. Granted, I've not done any exhaustive tests on it, but the two Schlage cyls I tested it on have seemed to confirm that it does, in fact, make bumping much harder - perhaps impossible? I don't know. I've been at each of these for about 10 minutes and I've not gotten either of them open yet. Before the modification, I could bump either in a few taps.

Now obviously, this would effectively reduce these locks to a 4 pin cylinder, but it would be a simple enough thing to employ this into a 6 pin cyl and you'd end up with a lock that had all the pick resistance of a standard 5 pin cyl, but also had some bump resistance.

I'd also like to see others try and reproduce this and tell me what they come up with.

Thoughts?

db

[digital_blue]

Couple things I forgot to mention...

It goes without saying that any lock that employed this would have to have at least one cut position at a 9 cut (ideally, first or last), and due to MACS, this would reduce the possible key differs somewhat.

db

[Omikron]

Good idea, but you have to remember that the springs and driver pins exist for a reason. Namely, here are the issues that I forsee with such a "fix":

- As the lock wears down, the pin that has to driver or spring may not move freely, and may get stuck, thus causing severe reliability issues in the lock.

- This method would not work for a cylinder mounted in the European configuration.

- It somewhat restricts how many available combinations there are, especiallyin masterkeyed installations.

[digital_blue]

- This method would not work for a cylinder mounted in the European configuration.

True enough. Obviously it would only work with locks installed "right side up" (just kidding.. I mean the North American way... ).

- As the lock wears down, the pin that has to driver or spring may not move freely, and may get stuck, thus causing severe reliability issues in the lock.

I'm not sure I'm convinced that this would actually represent a significant problem, but it would be worth a test. Certainly a valid point.

- It somewhat restricts how many available combinations there are, especiallyin masterkeyed installations.

Yes, as I indicated, but the choice to use a 6 pin instead of the 5 pin currently in use would eliminate all permutation reductions except those brought about as a result of MACS.

db

[digital_blue]

Ok.. some other thoughts as they come to me.

For this to be implemented, it would have to be done in random pin positions in locks. My original thought was that the best place would be the last pin position, but if installed in an otherwise 6-pin lock, simply a shorter bump key would work. In a similar manner, if it was always in the same place, a simple mod of a bump key would prevent it from hitting that pin position. So it's gotta be random.

As well, it was pointed out to me that not only would this not work in Euro profile cyls as noted, but any lever set where the lock is oriented horizontally it would not work.

Clearly, this is not a fix for every lock and every situation. But the only possibly "big" concern I see thus far is the possible failure rate as a result of dirt. I'm not sure how to get around that, but I guess the question would be how big a concern this would actually be? Would it represent a failure rate of 1 in 100? 1 in 1000? 1 in 100,000? Less? I'm not sure how to determine the answer to that question.

But barring that concern... seems to me that I would be better off with a Schlage 6 pin pinned in this config, than a Schlage 5 pin pinned normally. All the pick resistance, plus the added benefit of being (virtually?) unbumpable.

I've done some further testing tonight, and I can not get these puppies to bump open no matter how hard I try.

db

[Shrub]

[n2oah]

d_b, in my mind, those issues are certainly enough to make this anti-bumping measure do more harm than good. Compromising the reliability of a lock is not a good thing to do. If I were a lockie or a lock company, I wouldn't advise this measure. It might be okay for home use, as long as you keep a set of picks on you.

[UWSDWF]

i like the cut of your jib... gotta try this

[Bud Wiser]

Ok I realize I'm just a noob, so don't laugh if my defeat of your defeat is ridiculous.

Assuming you have done what you said to a lock, replace one stack with a 9 cut, I wonder how hard it would be that once we see bumping fails, to take a pick and find which is the dummy stack and then select another bump key with a 9 cut for that stack.

If that works, then all one would need to do is carry 5 extra bump keys for that cylinder with various 9 cuts on them.

Would you then go to trying 2 dummy stacks?

[Omikron]

A simple defeat for this countermeasure would be to simply take a pick and feel for the pin stack that has no spring pressure on it, and modify your bumpkey accordingly.

[UWSDWF]

A simple defeat for this countermeasure would be to simply take a pick and feel for the pin stack that has no spring pressure on it, and modify your bumpkey accordingly.

but in a situation where you are using bump keys in a "bad way" are you taking the time to find this stuff out and is the commoner thats is using bump keys to bad things gonna even know what to feel for?

[Bud Wiser]

A simple defeat for this countermeasure would be to simply take a pick and feel for the pin stack that has no spring pressure on it, and modify your bumpkey accordingly.

but in a situation where you are using bump keys in a "bad way" are you taking the time to find this stuff out and is the commoner thats is using bump keys to bad things gonna even know what to feel for?

probably not, they would just break a window in that case

[Omikron]

A simple defeat for this countermeasure would be to simply take a pick and feel for the pin stack that has no spring pressure on it, and modify your bumpkey accordingly.

but in a situation where you are using bump keys in a "bad way" are you taking the time to find this stuff out and is the commoner thats is using bump keys to bad things gonna even know what to feel for?

Well, the issue is that the positives of this modification do not outweigh the negatives. It's strictly a matter of "security through obscurity", and weak obscurity at that, until the method is revised.

[Gordon Airporte]

Bud and Omikron had the same idea I did, you would just end up carrying five or six bump keys for each profile, with a ramp removed at each pin position.
You could maybe put a very short master key spacer at the top of each stack (with springs, now), above the shear line - the idea being that the bump energy would transfer and pop that spacer up, leaving the other driver blocking the shear line.

[mrdan]

Well one could design a wafer and pin tumbler hybrid. Pins would be for security and the wafers (being one solid piece) would defeat the bump. You would only need one or two wafers to make it un-bumpable. This would force one to pick it manually. I don't know how practical it would be to do though.