Safe Cracking with Feynman - Numberphile

A chat about some of the ways legendary physicist Richard Feynman cracked safes (filing cabinets) at Los Alamos during the Manhattan Project.
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Discussed by Professor Roger Bowley.

NUMBERPHILE

Videos by Brady Haran

[BillM]

Feynman was not only a super genious (yes, my favoite scientist ever), he was also a notorious prankster. The man lived life to the fullest, all the while.making beautiful contributions to science as well as to his students and colleages. Amazing man. I think this guy sells him a little short. He was a tremendous collaborator and manager of people as his duties on the Manhattan Project reveal, and the young unknown guy on the team almost immeditely drew respect from many of the most brilliant and highly recognized men in their fields (and many famous). That says a lot!

[loz]

I wouldn't worry about angry safe enthusiasts. They don't get angry, they tend to keep things locked up inside.

[ColinCarmody]

In combination in most modern schools, you cannot set the combination, but you can easily find the first digit due to a flaw in the lock (apply pressure while rotating dile. Add five to the one number it gets stuck on.) then from there, after determining whether it is even or odd, you know both the second and third numbers are either even or odd (but all even, or all odd.) If there are 40 numbers, that gives you 400 combinations. But the third number doesn't require trying a new number everytime. Just set the first number, your guess for the second, then spin it around trying all numbers for the third one. Now, this is more like 20 different options, but doesn't require seeing the lock before breaking in. I have never used this technique for bad (nor should anyone) but I find it handy when I see that someone has stuck a lock in an unnecessary/obnoxious spot. Or if I find a lock, I can learn the combination then give it to a friend who needs one.

[losthorzon]

They didn't mention that he would tell the various people in charge of this security issue and they would get mad at HIM rather than fix the problem.

[numberphile]

As I understand it, when a cabinet was ALREADY OPEN he was able to use a "by touch" method of deriving the final two numbers in the combination as he seemingly twiddled the dial casually while chatting in the office - he then wrote down those numbers in a notebook or something, so he had the last two numbers on record!

I could have that wrong slightly!

[joncavanaugh]

My favorite story is when he pulled the General's top secret filing cabinet away from the wall and unscrewed the back off of it.

[UCLAursinho]

Per his autobiography, it is my understanding that Feynman also reduced the permutations by merging the rotation for the third combination with the beginning of the rotation of the first combination of the next number tried.

Since the dials required Right-Left-Right (or Left-Right-Left) turning, the first and third numbers were approached from the same rotation direction.

Also the first number required the dial to rotate over 360 degrees. The third number's rotation was less than 360 degrees. Feynman deduced that if he got the first two numbers correct, ignored the the third number entirely, and began spinning the dial for the first number of the next attempt, the lock would make a distinctive 'Click' as it passed over the correct third number.

So with a lock dial with 100 positions per turn of which he had already reduced to 20 positions per turn, he could cracking the lock in no more than 20 x 20 = 400 attempts (plus one extra spin) without any social engineering required. So at 5 seconds per turn, in a worse case scenario, he could crack the safe in about 2000 seconds (-32 min) and on average, -16 min).

[FhtagnCthulhu]

I love Feynman. His lectures, his life story, its all very inspiring. A great man, and an inspiring one. Always interesting.

[Ender]

The simplest trick he used is that some people didn't change the factory combinations, which were just a few. He started by trying them, and they often worked. Also, when he found some people left the cabinets open, and he could use the information, he advised them not to leave them open. That triggered a memo asking people not to leave the cabinets open when Feynman was around :-D

[imtalkingsostop]

Amazing how a tiny mechanical flaw can make it that much easier. I remember I used to crack open my friend's lockers at school, leave them in awe. Really all you had to do was if it wasn't cleared you could slowly turn it backwards (so if RLR opens then LRL). If you focused you could feel when the pins collided, which would give away the number for that dial.

[nidurnevets]

Thanks for posting this video. I am not a scientist, or mathematician, but I became interested in Feynman from seeing him interviewed on programs such as NOVA. I didn't realize that an uncle of mine taught him in school, until after both Feynman in my uncle, Abram Bader, had died.

[intellectualslacker]

I've been reading "Surely You're Joking, Mr. Feynman!" Awesome read, and I definitely recommend it to all audiences!

[amiradelal]

Richard Feynman is one of my favorites. In happy he has been getting more recognition lately on YouTube videos so other people can appreciate him.

[numberphile]

they exist - I spent much of the morning reading about them!

[trefod]

Loved reading the books about Feynman and watching interviews with him and his lectures. And look at that face, you can just see the mischief lurking in there.

[PureFreakinMagic]

Love that you used those pots to demonstrate turning the dials on this video. Very simple substitution for a dial and they just look good.

[nedogedell]

Agreed! The descriptions of his time in Alamos and the safecracking is my favourite part.

[Bangabalunga]

This is my favourite sixty symbol scientist. He is the most articulate and efficient of all the sixty symbol profs. Please do videos with him more often

[Bolu]

There is a CD of an entertaining talk ("Los Alamos from Below") that Feynman gave about his time at Los Alamos. I got it with the book "Classic Feynman." It goes through his whole story and ends with some safecracking stories. I would recommend both the book and the talk.

[HarryBalzak]

If you enjoy stuff like this(bypassing security) you will almost certainly like the lecture on YouTube called "I'll Let Myself In: Tactics of Physical Pen Testers".
I should probably warn everyone how unsettling it is that seemingly secure things are quite often not secure at all. Watch at your own risk of anxiety.