Description:
You deployed BitLocker using Active Directory only. You have setup the necessary Group Policy, run manual BitLocker Encryption and can see the recovery password is being store at Active Directory.
Now you are wondering how it could start auto encryption without user interaction.
Resolution:
From https://www.experts-exchange.com/articles/33771/We-have-bitlocker-so-we-need-MBAM-too.html we can see that we can create a task scheduler on the machine and run it with System credential.
Detail:
Task name: BL (name it as you want, but please don’t forget to change the name in the last script line)
Triggers: at logon of any user
Executing account: system
Action: powershell.exe with the argument \\server\share\BL.ps1
The script:
$pin=(Get-Random -Minimum 0 -Maximum 999999).ToString('000000')
echo "$pin" | out-file \\server\pins\$env:computername.txt -Append
$SecureString = ConvertTo-SecureString "$pin" -AsPlainText -Force
Add-BitlockerKeyProtector -MountPoint "C:" -Pin $SecureString -TPMandPinProtector
manage-bde -on c: -s -used -rp
msg * /time:0 Your hard drive is being encrypted. To start your PC, you need your Bitlocker-PIN, which is $pin
schtasks /delete /tn BL /f