Here's the scenario. We'got a Dell PE T110 (I know, I know), that we've enabled Bitlocker via TPM. On reboots, it asks to re-enter the bitlocker key, and we have no idea why it's not auto-unlocking. On the drive that's supposed to auto-unlock, we have the OEM parition, RECOVERY (with system,active,primary), and the OS (boot,pagefile,crash dump,primary partition) (Bitlocker encrypted). I've been reading that the OS needs to be the active partition for the autounlock to function. If not, any ideas where I should look next?
I've been reading that the OS needs to be the active partition for the autounlock to function
That isn't accurate.
This can be due to the recovery key being regenerated but not saved to TPM. By far the most likely cause is the C: drive not being first in the boot order. The next most likely cause is something in the hardware/firmware changed, which would basically mean it needs to be redone.
Here is a sample of what the manage-bde diskmgmt output should look like:
C:\>manage-bde -status BitLocker Drive Encryption: Configuration Tool version 6.1.7601 Copyright (C) Microsoft Corporation. All rights reserved. Disk volumes that can be protected with BitLocker Drive Encryption: Volume C: [OSDisk] [OS Volume] Size: 232.56 GB BitLocker Version: Windows 7 Conversion Status: Fully Encrypted Percentage Encrypted: 100% Encryption Method: AES 128 with Diffuser Protection Status: Protection On Lock Status: Unlocked Identification Field: Some description Key Protectors: Numerical Password TPM
Suffice it to say if there is not a TPM protector listed, the drive was not encrypted correctly/as you expected.