If Bitlocker had a backdoor it would have leaked by now. I don't believe that they could keep an "alphabet boys only" backdoor secret for that long. How would

If Bitlocker had a backdoor it would have leaked by now. I don't believe that they could keep an "alphabet boys only" backdoor secret for that long. How would that backdoor even look like? A some sort of master key that can decrypt every Bitlocker encrypted drive? Imagine if something like THAT got leaked. Who would have access to that key? Microsoft themselves? NSA? FBI? What about the UK, Australia or other US allies? Do their alphabet boys also get access to this? Do small town cops also get access? And I'm pretty sure lots of security researchers have tried to find vulnerabilities of Bitlocker. If there was something fishy going on - they would have noticed.