I use an encrypted external USB Hard Drive for storage. My PC no longer asks for a passphrase to open the Drive after a reboot or unplugging/replugging the USB cable. The Hard Drive just opens like an un-encrypted drive. The Ubuntu "Disks" tool shows that the external drive is still encrypted. The "Disks" tool also lets me toggle back and forth from Lock to Unlock, but neither setting enables the encryption. It is as if my PC just forgot that the external Hard Drive is encrypted.

I plugged the USB external Hard Drive into different Ubuntu (16.04) PC and encryption works fine. The alternate PC prompts for the drive's pass-code before the Drive can be opened. The encryption issue is specific to one Ubuntu workstation. The PC with the encryption issue is running Ubuntu 18.04 with all the software updates.

lekcin@SFF:~$ apt list cryptsetup -a Listing... Done
cryptsetup/bionic-updates 2:2.0.2-1ubuntu1.1 amd64
cryptsetup/bionic 2:2.0.2-1ubuntu1 amd64

In the Disks tool, with the top split screen highlighted, the paddle lock icon indicates that the Disk is locked, while the "Contents" line at the bottom of the tool reads UNLOCKED.

Thank you PerilDuck and Sebastian! I used the "Passwords and Keys" tool (AKA Seahorse) described in the "How to make login keyring forget a password" link provided by Sebastian. That resolved the issue. Now, when I try to open the encrypted Hard Drive, I'm prompted for a password. I also ran "sudo apt install cryptsetup" and it installed OK. Thanks Again.

  • 1
    I once had a simliar question about my external, encrypted USB backup HDD (just like your case) and the answer basically was "as long as sudo apt install cryptsetup is done, it will work". I recently did a fresh install of 18.04.1 and it worked out of the box. Do you also have that "split screen" in the disks tool? What does apt list cryptsetup say? Is it [installed]? – PerlDuck Dec 27 '18 at 18:35

When you want to mount an encrypted drive you are usually asked if you want the passphrase to be forgotten immediately, stored until logout or stored forever. Your description sounds as if as some point you selected "Remember forever" on that machine. So the passphrase most likely got stored in a so-called keyring. Check out this question on how to remove it:

How to make login keyring forget a password


The output of your apt list cryptsetup -a shows

Listing... Done
cryptsetup/bionic-updates 2:2.0.2-1ubuntu1.1 amd64
cryptsetup/bionic 2:2.0.2-1ubuntu1 amd64

which means the cryptsetup tools are not installed. If they were, it would rather look like

Listing... Done
cryptsetup/bionic-updates,now 2:2.0.2-1ubuntu1.1 amd64 [installed]
cryptsetup/bionic 2:2.0.2-1ubuntu1 amd64

Note the [installed] indicator after the first line. Just install them and you should be fine:

sudo apt install cryptsetup

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.