I wanted to encrypt my external drive with password, which is compatible in both Linux and Windows.

Truecrypt is an option. But the development of it is stopped few months back.

I came across crpytsetup in Ubuntu, which is said to work well in Windows with FreeOTFE.

I tried encrypting using cryptsetup in Ubuntu, when I put the same drive in Windows, It gave a warning message for format disk. When i gave format, it got formatted and started working well without any password. It is an unsafe option :(

Is there any other option which is compatible well with Windows and Linux ensuring the safety of the data? Okay if paid solution.

Thank you

  • 4
    The cryptsetup disk started working in Windows without a password because you wiped it out and replaced it with a Windows unencrypted disk.
    – Mark
    Oct 20, 2014 at 19:40
  • @Mark: Ecactly... But it is an unsafe option, if it asks for formatting the disk once i put it in Windows... Possibility of losing our content without notice is more...
    – Manoj G
    Oct 21, 2014 at 0:55
  • 2
    I would consider the prompt asking "Do you wish to format the drive" pretty good notice. Oct 21, 2014 at 15:47
  • Perhaps try asking on https://softwarerecs.stackexchange.com/ Dec 30, 2014 at 3:24

4 Answers 4


I don't think you understood what Windows did when it formatted the disk. When you plugged in the external drive, Windows couldn't read the filesystem (because it's encrypted) it therefore assumed the drive had no filesystem and offered to format the drive. You selected yes. Windows then deleted everything on the drive and overwrote it with a clean NTFS filesystem, with no data. This isn't insecure, because there's no data exposed to the Windows user. None of the encrypted data was ever available to any of the Windows users or processes.

I haven't explored FreeOTFE, but I assume if you ignore the Windows format option and instead install and use FreeOTFE you won't have a problem. Once the disk is decrypted, Windows will be able to read the filesystem and will be able to see data on the drive.

  • Yes, this is definitely the explanation of the second part of this question. If you would have put data on the disk after encrypting the disk in Linux, you would see an empty disk after formatting unencrypted in Windows. Just because the disk was empty in Linux, the asker thought that Windows could open it without password. That is not the case, even though the result (empty disk) is the same.
    – SPRBRN
    Oct 21, 2014 at 10:19

You can use dm-crypt drives, which have windows support as documented here: https://superuser.com/questions/584883/how-can-i-access-volumes-encrypted-with-luks-dm-crypt-from-windows

  • dm-crypt's window's support is FreeOTFE, who's development is stopped. But the problem is, we will be able to format dm-crypt drive in windows without any security. So trying to find an alternative...
    – Manoj G
    Oct 21, 2014 at 4:20

Another option is to look at truecrypt's successors, like Veracrypt (https://veracrypt.codeplex.com/). They use Truecrypt as a base but claim to add some additional security improvements. Of course since they're new it still remains to be seen whether these projects will be able to support themselves in the long term and whether they'll remain secure, so it's up to you to decide whether they're good enough for your needs.


If you want a "safe" solution, one where Windows does not offer to format the disk when you try to mount it, you need to use a format that is recognized by Windows.

You could install Ext4 drivers on Windows, but this will only work for those machines with these drivers installed.

You could use FAT32 or NTFS for the disk, and use Encfs or Truecrypt or another solution to create an encrypted file or folder. Then all Windows computers will mount the disk. Still - anyone can delete the encrypted file(s).

Better put a big sticker on the disk warning people not to mount this on Windows.

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