BitLocker is the Windows Operating System’s resident disk encryption utility. Using BitLocker, you can encrypt as many partitions of your computer’s Hard Disk Drive as you want, protecting the data on the encrypted partitions with not only a passphrase but also, optionally, a Trusted Platform Module. BitLocker is every bit as effective a drive encryption utility as all of the other options out there and, best of all, doesn’t require the installation of any third-party applications or the expenditure of any money as it is entirely built into Windows itself.
Users of BitLocker often have a number of different questions pertaining to the utility and how it and its encryption operates and behaves. One of the most common questions pertaining to BitLocker is what happens to a partition that is encrypted with BitLocker when a user’s primary partition (the one that houses their Operating System) is formatted, say in the event of a clean installation of Windows.
Well, it is always recommended that you decrypt all BitLocker encrypted partitions before formatting your Operating System partition, but in the event that you do not do so and go ahead with the formatting of your OS partition, you will see that all other BitLocker encrypted partitions will be locked once you boot into your computer’s newly clean installed Operating System. When you encrypt a partition of your Hard Drive, BitLocker functions on both the drive that is encrypted and your primary OS drive – this is probably the reason why all other BitLocker encrypted drives become locked in the event that your OS drive is formatted.
When you format your OS drive, clean install Windows on it and then boot up your computer, Windows will still be able to see all other BitLocker encrypted drives but will not be able to access them. When you try to access a BitLocker encrypted partition after formatting your primary OS drive, you will see that it is locked and requires its recovery key in order for it to be unlocked.
You see, when you setup BitLocker on a partition of your computer’s Hard Drive and create a passphrase for it, BitLocker provides you with a 48-character recovery key to be used to unlock your drive in the event that you lose/forget your passphrase or the structure of the partition (or your OS partition) changes. This recovery key can either be printed out (or written down) or saved to a different drive such as an external HDD or USB drive. If you format your OS partition while one or more of your other partitions are still BitLocker encrypted, they will be locked, and you can simply use the BitLocker recovery keys for the locked partitions to unlock them.