So when the British cracked the top level German code Ultra during WW2 they went to incredible lengths to conceal what they now achieve on a technological level when it came to code-breaking, because they (quite sensibly) knew that if the Germans realised the Brits could read all their super-duper secret stuff they would immediately change how they encoded their evil mutterings.
Churchill was SO desperate to keep their new edge a secret that he allowed the city of Coventry to be bombed flat rather than let the Krauts knew that HE knew they were coming. In the same way, he allowed convoys of ships to be sunk rather than let the Krauty Krauts know that HE knew they were about to send hundreds of British seamen to the bottom..
It would thus be TOTALLY insane for Kim Jong-un to figure out how to use hackers to penetrate the MOST STRINGENT firewalls and cyber security the US can muster for absolutely NO reason at all apart from embarrassing a few coke-snorting, rent boy-shagging, Porsche-driving Hollywood producers.
It would be utterly insane to invest huge state resources in developing the capability to perform such hacks, and then let EVERYONE know that you can get through their cyber locks and padlocks, because they will naturally immediately up-grade their cyber security to levels you will be unable to dance through quite so easily.
Yep. It would be stupid. Silly. Insane. A barking mad thing to do.
Which means that it’s almost CERTAINLY completely 100% true that Kim Jong-un absolutely DID order his splendidly name Unit 121 hackers to penetrate the Sony cyber vault and then leak embarrassing stories about Angelina Jolie.