There is a key(file) and it is the user's responsibility to back it up. I Google'd "bitlocker enabled by default on new machine" and the first hit was this:So, that leaves one question: if you install w10 pro and never enable or use bitlocker, is there a default password? If so, it sounds like if it is enabled later and you've never used a microsoft account to back up the mystery password youwill never be able to unlock it? Or, when bitlocker is enabled for the first time will it then ask you to create a password. Very curious about this if you know the answer.
My ***guess*** is that a new Win10 user who is first logging in to their machine is greeted with (something to the effect of) "By the way, your entire HDD or SSD is encrypted and tied to your motherboard. Back the key up or risk losing everything if/ when these two things are de-coupled" and is one of about 1,000 ridiculous screens and prompts a user gets and absent-mindedly clicks through, like a EULA. I've never bought a new computer with Windows pre-installed so I am not certain to what extent a user is warned and (hopefully) warned again; but I know that when enabling BitLocker it is made reasonably clear that YOU THE USER are the sole steward of this key. I treat these kays with the same care and paranoia as I do SSH and PGP keys.