(Okay, ending sarcasm.)
Find it hard to believe they stopped, reads more like a note saying to stop keeping "official" records.
You can absolutely refuse to talk to the FBI.
Security services are in a bind when it comes to people like Feynman. On the one hand, experienced agents would have known this guy was no Soviet spy. On the other, every time someone makes an accusation they're sort of duty bound to at least ask him about it, because if it later turns out he is up to something nefarious people will accuse them of ignoring the evidence. That's just how bureaucracies work, and you don't move up in that sort of environment by ignoring the ground rules.
I suspect whoever was charged with running down poison whispers was perfectly happy to be ordered to stop. They got to stop wasting time and concentrate on stuff that might matter, while at the same time on the outside chance it came back to bite them they had documentation of being ordered to ignore him, effectively shuffling the blame up the ladder.
By cyber-security standards the physical and information security measures taken during the Manhattan project were pretty amazingly pointless. They did a good job of keeping the process of enriching uranium secret from the regular folks that worked on it, but that just kept them from going home and talking to their friends.
The scientists working at Los Alamos knew an incredible amount about what was going on and therefore represented single points of failure.
If a spy had been able to infiltrate Oak Ridge, granted they wouldn't have gotten to see many steps of the process but the fact that lay-people didn't know what they were working on didn't mean much.
The main security for the project probably lay in the fact that economically no other nations involved in WW2 could have attempted such a program, even with day-by-day updates of exactly what we were doing. By the time the kinks were worked out it would have been way too late for any other entities to attempt to copy it.
The past tense implies the intelligence community is better behaved now. The old threat was communism, now it's terrorism.
I would be surprised if he's the first guy to try that.
The trick with social engineering people back in those days was getting the typewritten formats identical. Being Feynman all he would have needed was one actual memo to copy from and away he goes.
I thought Feynman was a physicist. What skills are you speaking of? Was he a spy in a former life or something?
It was usually silly things, like locking one cabinet drawer, but not an adjacent one, so someone with long enough arms could just reach into the cabinetry and get their hand inside the other drawer. Or just knowing the birthday of the person whose safe he wanted to crack, and 90% of the time that was the combination. I think in one incident, the safe was just simply left unlocked. But of course, Feynman doesn't disclose those little details to the people around him, and quickly became known as a lockpicking legend.
Edit: He also was an artist who sold several works, and an avid percussionist who played with groups in Brazil, and many other things I'm forgetting. I'd really recommend reading "Surely You're Joking" or any other book about him, his life is incredible and hilarious.
Basically, all of the combination locks had 2 digits of leeway. So if your first code was 20, you could set the lock to anything from 18 - 22 and it would still open.
This meant that instead of the locks having 100 x 100 x 100 = 1,000,000 combinations, they instead had something closer to 20 x 20 x 20 = 8000 combinations. He would then brute force the 8000 combinations through a combination of trying the more likely ones first and if that failed, just brute forcing it over a few hours.
The locks were made easier to brute force in that unlike modern locks, the 3 combinations would be input on 3 separate dials so you can set the first two to the 'right' value, then just spin the third while attempting the handle at the same time. This meant you could try literally every possible combination in ~10 hours of work.
As for an example of easy ones would be a birthday or anniversary.
- code 1 = day 1-30(6 combos)
- code 2 = month 1-12(3 combos)
- code 3 = year 1-99 (20 combos) (This would likely be 9-10 combos if he accounted for the distribution of likely dates)
So to try every date combo, you would only need to try 360 attempts in the worst case.
then there's the paddle technique, not sure what its called, but after the first number is set, the 2nd number has to be at least past the point where you feel the "paddle" contact the 2nd wheel in the series. Higher-end safes counter this somehow.
At my high school some decades ago we had the 3-turn 0-39 master locks but mfgr sloppiness meant there were really only ten or so possibilities and if you knew the last digit you only had perhaps 100 or so combos to try which doesn't take long.
A frenemy of mine got into a practical joke war and my friends collected tens of thousands of magazine subscription cards from the school library over the course of weeks and filled his locker with them when I finally brute forced the lock. He responded by filling my locker with many thousands of 4-40 sided machine tool nuts and some washers fed in thru the top ventilation slots. Well, it all seemed like a good idea at the time.
Small time barely noteworthy events happened all the time like remove the lock and attach it to the locker upside down, or replace it with a different lock, or swap it with a neighbors lock, or remove and/or change the numbers on the locker door. Oh another move was breaking into a locker, and respectfully not touching any personal property but disassembling the interior of the locker such that the victim no longer had a coat hanging hook.