Bump-proof lock idea

[doublez]

Hi everyone,

I was thinking about lock bumping the other day, and came up with an idea for a bump-proof lock.


(pardon the crappy drawing)

To be clear, the middle pin in the first chamber is blocking the shear line while the lock is at rest.

When someone tries to bump the lock, the energy will be transfered from the key pin into the middle pin, and from the middle pin into the top pin, thus the middle pin will still be blocking the lock from opening.

Any thoughts on how well this would work?

-dz

[cheerIO]

I'm no expert but it just looks like you put a master wafer in there.

I understand that you are going for the Newton's cradle effect to keep the middle pin in place but I think that it has been proven that things are a lot more random in the bumping process than that.

Plus you have just put two shear lines on that pin. So, twice the chance to open on bumping if it does move and you just made it a lot easier to pick.

I think a better idea would be to put the longest keypin in possible. That way if the pin raised at all, the lock would not open. Also a good thing to have in there so you can hide some high-lift pins behind to thwart picking.

[Robotnik]

Hi everyone,

I was thinking about lock bumping the other day, and came up with an idea for a bump-proof lock.


(pardon the crappy drawing)

To be clear, the middle pin in the first chamber is blocking the shear line while the lock is at rest.

When someone tries to bump the lock, the energy will be transfered from the key pin into the middle pin, and from the middle pin into the top pin, thus the middle pin will still be blocking the lock from opening.

Any thoughts on how well this would work?

-dz

If I understand correctly, what you're talking about effectively boils down to bumping a master keyed lock (key pin and driver pin separated by a third wafer) with only one chamber mastered. I can say from having personally managed it with several different locks that mastering is no practical deterrent to bumping; believe there was also a thread on this recently.

[Robotnik]

It appears I was a bit late to the party; carry on ! CheerIO summed up exactly the sentiments I was going for.

[doublez]

If I understand correctly, what you're talking about effectively boils down to bumping a master keyed lock (key pin and driver pin separated by a third wafer) with only one chamber mastered. I can say from having personally managed it with several different locks that mastering is no practical deterrent to bumping; believe there was also a thread on this recently.

I don't think it's quite the same, since on a master keyed system, the master pin would be below the shear line when the lock is at rest. My idea has one shear line, because the middle pin can never be completely below the shear line.

I understand that you are going for the Newton's cradle effect to keep the middle pin in place but I think that it has been proven that things are a lot more random in the bumping process than that.

I recall a video of Schuyler Towne at Defcon saying something to that effect, and it makes sense, but I've never really seen any evidence either way.

I think a better idea would be to put the longest keypin in possible. That way if the pin raised at all, the lock would not open. Also a good thing to have in there so you can hide some high-lift pins behind to thwart picking.

That makes sense. Are max length key pins enough to make this work? I'm not sure what the timing of bumping a lock looks like, so I don't know if the pin would already have gone back down while there's a split in the shear line.

[Robotnik]

You've got me curious; I'll pin a cylinder up as a test subject and see what happens.

[Snowblind]

Instead of the bump-stop pinstack with the two driver pins being flat surfaces against each other like master-keyed pins, what if the two driver pins were cut down the middle at right angles, like steps, or forked, so no shear line or setting was possible between them?

I'd suppose the lock might be ruined if they were jostled in such a way that one driver pin got bumped and twisted into the cuts stacking on top of one another, but it'd be impossible for the bump to set the pin with the whole Newton's Cradle thing if the shear line between the two driver pins wasn't straight.

[Robotnik]

You've got me curious; I'll pin a cylinder up as a test subject and see what happens.

Result is what I was expecting, but had to try. Pinned this up with a 1 in the fifth position and a mid-driver pin that would block the shear line at rest and with a bump key (6 cut on a Kwikset) inserted. Plug turned on the second tap.

The Newton's Cradle/pool ball analogy can be a troublesome one with regards to lock bumping. The transfer of force isn't as clean as with either of these; there are far more variables in play - different pin weights, friction from the cylinder walls and, most importantly, spring tension pressing down from above.

[doublez]

You've got me curious; I'll pin a cylinder up as a test subject and see what happens.

Awesome

Result is what I was expecting, but had to try. Pinned this up with a 1 in the fifth position and a mid-driver pin that would block the shear line at rest and with a bump key (6 cut on a Kwikset) inserted. Plug turned on the second tap.

The Newton's Cradle/pool ball analogy can be a troublesome one with regards to lock bumping. The transfer of force isn't as clean as with either of these; there are far more variables in play - different pin weights, friction from the cylinder walls and, most importantly, spring tension pressing down from above.

Thanks for testing it.

I'd suppose the lock might be ruined if they were jostled in such a way that one driver pin got bumped and twisted into the cuts stacking on top of one another, but it'd be impossible for the bump to set the pin with the whole Newton's Cradle thing if the shear line between the two driver pins wasn't straight.

I don't quite get this, could you explain a bit more? I don't see how having the driver pins interlocking would make it impossible to bump.

[deralian]

Master pinning a lock would simply make it easier to gain access to. More sheerlines to pick and as far as bumping, all you need is to get a pin above the line and you can turn the lock.

[Snowblind]

I'd suppose the lock might be ruined if they were jostled in such a way that one driver pin got bumped and twisted into the cuts stacking on top of one another, but it'd be impossible for the bump to set the pin with the whole Newton's Cradle thing if the shear line between the two driver pins wasn't straight.

I don't quite get this, could you explain a bit more? I don't see how having the driver pins interlocking would make it impossible to bump.

I mean, it'd be impossible to use the additional pins as a additional possible ways to set the pin. So unlike a master-keyed pin stack, you'd only have one possible shear line, the one for the key to work, the other pins could be shaped to make it impossible to set them. So you'd still have extra pins in that stack to buffer against bump attempts but it would not make it any easier to pick open.

[Robotnik]

I'd suppose the lock might be ruined if they were jostled in such a way that one driver pin got bumped and twisted into the cuts stacking on top of one another, but it'd be impossible for the bump to set the pin with the whole Newton's Cradle thing if the shear line between the two driver pins wasn't straight.

I don't quite get this, could you explain a bit more? I don't see how having the driver pins interlocking would make it impossible to bump.

I mean, it'd be impossible to use the additional pins as a additional possible ways to set the pin. So unlike a master-keyed pin stack, you'd only have one possible shear line, the one for the key to work, the other pins could be shaped to make it impossible to set them. So you'd still have extra pins in that stack to buffer against bump attempts but it would not make it any easier to pick open.

The OP's theory had a middle pin that can never fully enter the pin chamber, negating it as an additional shear line (since the shear point created by the middle and the top pin is permanently above the shear line, even at rest). This isn't so much an issue of added shear lines as it is a transfer-of-force issue. The introduction of exotic-shaped interlocking pins wouldn't do much to negate this, as long as the pins are in contact with each other.

[Robotnik]

Sorry, that should have read "enter the plug's portion of the pin chamber." Of course it's in the pin chamber, just never drops below the shear line .

[DR_WOLFSBURG]

I am a locksmith in OC California,

they do have "bump Proof" locks the thereory is more than simple and doesnt sound like it wouldnt work, but it does.
To make a "bump Proof" lock, just replace the top driver pins with longer driver pins. up them a few .005s
I bump a lot of locks lol and this really seems to work. I know Master Lock makes a Bump Proof dead bolt. But its still crap, becuase its master lock lol

I hope this helps a little

[kwoswalt99-]

I am a locksmith in OC California,

they do have "bump Proof" locks the thereory is more than simple and doesnt sound like it wouldnt work, but it does.
To make a "bump Proof" lock, just replace the top driver pins with longer driver pins. up them a few .005s
I bump a lot of locks lol and this really seems to work. I know Master Lock makes a Bump Proof dead bolt. But its still crap, becuase its master lock lol

I hope this helps a little

I don't see how this would work.