Bump keys make lockpicking disappointingly easy for locks that are easy to pick. They take something that's a nice challenge for a beginner and make it easy for anyone.
However, a good lock that's difficult to pick for anyone, with or without bump keys or comprehensive experience, is pretty easy to come by. That said, the hard thing is often knowing the difference: expensive and heavy are not necessarily good hints.
From around the 35 minute mark in the "What The Bump" talk, security researcher, TOOOL founder and President Barry Wels said:
"It [bumping] also works on these high security locks: multiple rows with dimples, keys that look really dangerous thinking if I have these on my door I'm really safe. The thing is, they open just as easy as the other locks, as far as we've seen. The only problem is getting bump keys. We really had some help from some of the state of the art Dutch locksmiths, with very advanced tools to make these keys. But once you have these keys, they're just as easy to open as the other locks. One of the statements which is my favorite is: I think you can teach this to a monkey to open locks like this. I'm still looking for somebody with a monkey to actually shoot some video. If you know somebody with a monkey that we could train to do this, that would be fun.
"It also works with locks with moving parts in it. The ball offers no protection because you take the original key, it has all the information already in it. The ball is always in the same position or there are two different spacings of the ball. It all works the same, because there are a lot of locks with protective measurements that are standard for all the locks. So once you have a key that is cut to the deepest, these mechanisms are still in place. The ball is still there, for instance, and it will still open.
"We opened some some pin-in-pin locks. The brand name is Mul-T-Lock. They were not happy that we opened them, and they were not happy that they were being mentioned in a white paper, and they more or less demanded a public test to show that it wouldn't work. So when the guy was at our place I explained to him how the technique actually worked, because he had no clue. So then he demanded a closed test where the results were kept secret. I said I'm willing to do that. He also put a time limit of four days or something ridiculous like that. So I said I'm willing to do that but it will be on a commercial basis because I can not use the information for my website, you want to keep it private. When I told him my price just to keep it friendly -- I wasn't asking a lot of money -- he ran away and never seen again. I do hear he's still very angry. But if Mul-T-Lock wants a serious test, they can always contact me directly, but not through this Dutch sub-dealer of them.
"We opened some impossible locks. By impossible, I mean I opened some locks, and you can see it on the other video, it's available online if you go to the toool.nl website. I opened some locks that I would never open without damaging it ever, because the mechanism is so well designed. There's only one flaw, which is that the part that makes it secure stays the same in all the keys, and only the variation pins change. I'm talking now about the Assa Twin lock. It's a lock with two rows of pins, and the secure row of pins is always the same in a certain region, which makes it very vulnerable for this attack. Talking about the Assa Twin, another reason that I thought I would never be able to open a lock like that is that it was so well engineered, the tolerances are so small, if the pin is half of a millimeter or a tenth of a millimeter too high or two low, the whole lock does not work any more.
"This is also something that we found, that the tighter the lock is made, the more engineering is put in to the lock, the better this technique works. If the key that slides in to the lock wiggles too much because the key has got a lot of space in between, the energy transferred is a little bit lost. If the pins in the chamber have a lot of tolerance and are not straight in the house, but a little angled or a little bit left-right, the energy is not transferred ideally. So the more expensive and the more engineering is put in to a lock, we found most of our favorite locks opened within a few blows because they are so well designed that they are perfect impact energy transmitters that allow smooth transmission of this energy."[1]
That said, since the technique of bumping made a big splash in the mainstream media, lock manufacturers have experimented with and released locks with "anti-bump" features. Those locks might not be as susceptible as the locks that were the subject of Wels' talk. On the other hand, there are and will continue to be plenty of locks in use that don't have any anti-bump features at all.
His opener about the monkeys refers to "these high security locks", but the description that follows seems to describe locks that are big and heavy and look intimidating, but don't actually deliver any challenging security. This is, in my experience, quite common.
He does then go on to describe bumping more challenging locks, but I'm not convinced these would be as easy. Especially for a monkey...
I didn't hear him mention the size or weight of the locks they tested anywhere. Please point out where he says that.
If you are skeptical of their results, I urge you to try the technique yourself on some locks you consider to be worthy of the challenge and publish your results.
He doesn't mention size or weight, but I was extrapolating from this line:
> that look really dangerous thinking if I have these on my door I'm really safe. The thing is, they open just as easy as the other locks
which makes it sound like he's describing locks that seem secure, rather than locks that are secure (e.g. because of their look, advertising, weight, size, colour, whatever).
I could be misreading him. I'm not contradicting the text, just interpreting it. If he genuinely means that very secure locks can be opened by a monkey/beginner with a bump key then I'd take his word for it. I'm just not sure that that is what he's saying.
My takeaway from his talk was a wide range of locks were vulnerable to bumping, including locks that were highly resistant to other attacks, including "some locks that I would never open without damaging it ever" and "most of our favorite locks" (ie. otherwise truly excellent locks).
So to claim that locks that are difficult to pick are necessarily difficult to bump runs counter to the findings expressed in this talk. In fact, the findings are quite the opposite, as many locks that are difficult to pick because of the tight tolerances and high quality engineering are actually easier to bump than locks which are easy to pick.
However, a good lock that's difficult to pick for anyone, with or without bump keys or comprehensive experience, is pretty easy to come by. That said, the hard thing is often knowing the difference: expensive and heavy are not necessarily good hints.