#Microsoft’s developers had failed to remove or “strip” the debugging symbols[..]Inside the code were the labels for the two keys. One was called “KEY”. The other was called “NSAKEY”[..]Fernandes reported[..]to “Advances in Cryptology, Crypto’99” conference held in Santa Barbara[..]Windows developers[..]did not deny that the “#NSA” key was built into their software. But they refused to talk about what the key did, or why it had been put there without users’ knowledge.
https://washingtonsblog.com/microsoft-programmed-in-nsa-backdoor-in-windows-by-1999/