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I'm unsure if this is possible in terms of a software solution, but what I would like to be able to do is require pre-boot authentication with full-disk encryption on a dual-boot system (Linux + Windows).

My partition layout is as follows

  • Xubuntu
  • Swap
  • Windows XP
  • NTFS for files

I haven't been able to find a solution, so I figured I'd give it a shot and ask here.

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See also security.stackexchange.com/q/14227/3272 –  Tobias Kienzler Sep 17 '12 at 9:19
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7 Answers

up vote 3 down vote accepted
+50

HOWTO: Set up Full Disk Encryption in a Dual Boot System.
(Using Truecrypt, Ubuntu+Windows)

TrueCrypt leaves behind a string in its boot loader that identifies it as a TrueCrypt boot loader. You can change this with some fiddling: Modify Truecrypt encryption boot loader strings.

Note that even with full disk encryption someone can still access the data if they have physical access to the PC within a few minutes of it being powered off: Cold boot attacks on encrypted partitions. (Freeze ram, remove from pc, read key!)

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I think the best solution is to separately encrypt the XP and Xubuntu partitions with TrueCrypt for XP, and cryptsetup with LUKS for Xubuntu.

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+1 - use the best tool for the job in each case, there's no reason you need to use the same tool for both operating systems. Your boot menu loads before any decryption occurs anyway, so just set up encryption as you normally would on both. –  thomasrutter Jan 12 '10 at 3:33
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I've heard many good things about TrueCrypt, especially in the context of what you are looking for. I know that it offers options for full-disk encryption and password authentication and am almost positive that such features will work on a dual-booting system as well.

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I would recommend the search terms "grub" (as in the boot loader) and "encryption."

The first link that came up for me under Google was this, and I bring it up because one of the comments pointed out (rightly, I think) that even if you do do whole-disk encryption, you will still want to have your boot partition on an external trusted device (to prevent rooting), like a USB key or something.

From what I as able to gather from a brief scan of a couple links is that basically you will need to have an unencrypted boot partition for both Windows and Linux that can be loaded by GRUB (which can be password protected).

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Many BIOSes have an option for disk protection. I'm not sure exactly how it differs from disk encryption, but basically the idea is that you have to put in the hard drive password before it will spin up. This is superior to the BIOS password method, because even if you move the disk to a different computer, it still requires a password. I've seen this option in my BIOS and others, but I'm not sure exactly how it works or how cross-compatible it is, but it might be something to look into.

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Whilst Windows and Linux both have their own encryption technologies, I do not think there are any pre boot solutions that work on both.

Your best bet would be to use either a software based solution such as Truecrypt* or look at your usage habits and virtualise one in another... For example, if you do not do anything intensive in Linux, I would virtualise it so that you can use Windows as your primary OS and then use Bitlocker.

(*) I realise that this is not what you want, but there isn't really many encryption solutions that are cross platform, let alone pre boot.

EDIT -

Just read the documentation, and it looks like Truecrypt does/can do pre boot authentication... but I have never used this feature and cannot really give any advise other than to say Truecrypt is a good product!

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Regarding the boot password, you may use a boot manager to handle the dual booting, one that supports passwords. The encryption can be done per operating system using available tools.

Some such programs are:

BootIt NG ($34.95)
This is the only one of the list with which I have personal experience and can testify that it's indeed maybe the best of its kind.

enter a password/keyword that will be required to boot this item (operating system)

GAG (freeware)

Allows a password to be put on each operating system, denying access to non-authorized people.

PLoP Boot Manager (freeware)

Password protection for the computer and the boot manager setup

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