Yes, our compliance policy is the machine has to be 100% encrypted before a 
user touches it. We run the cipher.exe command after encryption (3rd party not 
Bitlocker) and after a reboot.

Our average time is about 15-30 minutes on a 250GB SSD and about 30-90 minutes 
on a 256GB spindle drive.

Daniel Ratliff

From: [email protected] [mailto:[email protected]] On 
Behalf Of Miller, Todd
Sent: Tuesday, May 26, 2015 4:01 PM
To: [email protected]
Subject: RE: [MDT-OSD] Bitlocker drive encryption process overly slow ?

Is it any faster to use cipher.exe to blank/randomize the unused space than it 
is to just encrypt the whole drive?  I'm asking, not arguing.

Do you just run that as the last step in the OSD process?  My primary goal is 
to not have to wait very long for encryption to finish before the computer can 
be used, but make sure encryption finishes in the background in a reasonable 
time and then reports up that it's fully encrypted status to MBAM.  I don't 
care too much if it is not fully encrypted when I give it to the user, but I do 
want it to be fully encrypted within a day or so.

What would fit my needs best is if there were a way to do an "encrypt used 
only" during OSD and then flip a switch so that bitlocker goes back and 
encrypts the rest of the drive (whole drive) later in the background.  Finally 
when it is at 100% it can report to MBAM that it is encrypted.

Is your goal to be 100% encrypted before you let a user onto the machine?




[email protected]<mailto:[email protected]> 
[mailto:[email protected]] On Behalf Of Daniel Ratliff
Sent: Tuesday, May 26, 2015 9:33 AM
To: [email protected]<mailto:[email protected]>
Subject: RE: [MDT-OSD] Bitlocker drive encryption process overly slow ?

Our security team had similar concerns and accepted running the cipher command 
before encrypting to wipe the all data.

Cipher.exe /w:c:\

Daniel Ratliff

From: [email protected]<mailto:[email protected]> 
[mailto:[email protected]] On Behalf Of Miller, Todd
Sent: Tuesday, May 26, 2015 10:24 AM
To: [email protected]<mailto:[email protected]>
Subject: RE: [MDT-OSD] Bitlocker drive encryption process overly slow ?

When pre-provisioning and encrypting used space only, remember there may be 
previously unencrypted data that is recoverable on the drive from a previous 
unencrypted OS installation - - as Michael mentioned "an empty drive" - that is 
an important point.

If you are concerned about data leaking out, you need to either start with a 
securely cleaned disk (f-disk is not enough),  a  brand new disk, or a 
previously wholly encrypted disk - otherwise you should  encrypt the whole disk.

I was thinking that the used space was going to be great, forgetting that there 
would be a lot of chance for leakage if you are moving from an unencrypted disk 
to an encrypted disk environment.   All the unencrypted stuff from the disk's 
previous installation will be left unencrypted in a used only scenario.


From: [email protected]<mailto:[email protected]> 
[mailto:[email protected]] On Behalf Of Michael Niehaus
Sent: Monday, May 25, 2015 7:10 PM
To: [email protected]<mailto:[email protected]>
Subject: RE: [MDT-OSD] Bitlocker drive encryption process overly slow ?

Remember too that Windows 7 encrypts every sector - encryption of used space 
only was introduced with Windows 8.  Encrypting 500GB will certainly take a 
while on a spinning drive.

Leveraging BitLocker Pre-Provisioning also enables used space only encryption - 
that makes it instantaneous to turn on for an empty drive.

Thanks,
-Michael

From: [email protected]<mailto:[email protected]> 
[mailto:[email protected]] On Behalf Of Keith Garner (hotmail)
Sent: Monday, May 25, 2015 4:52 PM
To: [email protected]<mailto:[email protected]>
Subject: RE: [MDT-OSD] Bitlocker drive encryption process overly slow ?

12 hours seems a bit excessive, however all of my machines have migrated over 
to SSD drives, so I may not be the best judge of spinning drives.

The other alternative is to enable Bitlocker Pre-Provisioning from the Windows 
8.0/8.1 ADK. Basically, it will encrypt the drive but leave the protectors 
"off", if you have ever "suspended" Bitlocker, it's similar. The Bitlocker is 
just "ON" and there is no need to go through the lengthy encryption phase.

I've seen it work for Windows 7 SP1, and If you are using a product like MBAM, 
it should utilize the encrypted state of the drive and enable the protectors.

From: [email protected]<mailto:[email protected]> 
[mailto:[email protected]] On Behalf Of Bain.John
Sent: Monday, May 25, 2015 11:46 AM
To: [email protected]<mailto:[email protected]>
Subject: [MDT-OSD] Bitlocker drive encryption process overly slow ?

Just curious to hear what others have seen in terms of whole drive encryption.

Does 12 hours to encrypt 500 GB seem excessive ?

This is to encrypt the drive post Windows 7 install.

John

John Bain - CIC Engineering
Office: JETS C657 | Tel: 613-437-6829
365 Laurier Avenue West Ottawa ON K1A 1L1 | 365, avenue Laurier Ouest Ottawa ON 
K1A 1L1
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solutions et de la gestion de l'information
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