How to gain encrypted email on the Chromebook

If you've been waiting for encrypted email to arrive on Chrome OS, thanks to Android apps, it is now ready for prime time. Jack Wallen shows to make this so.

Image: Jack Wallen

I needed to use encryption on my Chromebook. For the longest time I was working with encryption apps, like Minilock. Eventually it became clear this wasn't the most efficient use of my time. So I waited for a better solution.

That solution came in the form of Android app support. I was lucky in that I owned a Pixel 2, which enjoyed Android app support fairly soon. Because of this, I was able to install the necessary Android apps to make encryption much easier. The apps I chose to handle this task were an easy choice, K-9 Mail and APG. Once installed, I was able to take care of my encryption needs without having to jump through unecessary hoops.

Let's walk through the process of installing these apps and then using them to encrypt email.


First, you must remember that these apps can only be installed on a supported Chromebook. To find out if your Chromebook can work with the Android Play Store, check out this official list. If your Chromebook is supported, you'll then need to enable Android app support (find out how in my piece "How to install Android apps on your supported Chromebook"). With that taken care of, let's walk through the process of installing these apps.

In the Chrome OS menu, you'll find an entry labeled Play Store (beta). Tap (or click) on that entry and then search for K-9. Locate and tap (or click) the entry by K-9 Dog Walkers and then tap (or click) Install. Once the app completes installation, go back to the Play Store main page and search for APG. Locate and tap (or click) the entry by Thialfihar. Tap (or click) Install and allow the process to complete.


I've already outlined the process of setting up K-9 Mail to be used with APG (read "Encrypt your email on Android with the help of K-9 Mail and APG"). The process is the exact same on Chrome OS. However, I have found a much more efficient way of sending an encrypted mail, thanks to APG. Here's what you need to do:

Once you have both K-9 and APG set up (and your key either generated or imported), you'll first need to import the keys of those you plan on sending email. To do that, follow these steps:

  1. Open APG
  2. Click on Import Keys from the main window
  3. From the Keyserver drop-down in the upper left corner (Figure A) select either Keyserver (if you'll be pulling the key from a public keyserver) or Import from file (if you have the user's public key available locally)
  4. If pulling a key from a keyserver, enter the name associated with the key and tap the search button
  5. When the username/key appears select it for import
  6. If importing from a local file, tap the Open button, locate the key (an .asc file) and then tap Import selected keys

Figure A

Figure A

Importing keys with APG.

That's it, you have successfully imported keys for use with APG. Now, let's encrypt a message for one of those users.

You'll be surprised to find out that the message can be more efficiently created from within APG. Instead of working from within K-9, open up APG and tap on the Encrypt button. In this new window (Figure B), make sure PUBLIC KEY is selected and then click Sign (if needed). If you opt to sign the message, you will also be required to select the key with which to sign the message.

Figure B

Figure B

Creating an encrypted message within APG.

Click on the Select button associated with Recipients and then choose from those recipients for which you have imported public keys (you can select more than one). Once you've selected your recipient, click OKAY.

At this point you have two choices: You can either manually type a message or you can attach a file to be encrypted to the recipient. If you select MESSAGE, you type the message in the bottom pane. If you select FILE, you'll then click the browse button, find and select your file. Let's type the message manually.

Type your message in the text area. Once you've typed your message, you can either share the message or copy it to your clipboard. Since we've installed K-9, we can click Share with, enter the passphrase for your PGP key, tap (or click) OK, and, when prompted, tap (or click) K-9 Mail (Figure C).

Figure C

Figure C

Selecting how to share your email with APG.

At this point, K-9 Mail will open (Figure D). Type in the email address for the person (or persons) you are sending the encrypted mail to (the same recipients you selected when encrypting the message). Click Encrypt and (if necessary) Sign. Enter a subject and then click the Send button. You will, once again, be prompted for the passphrase for your encryption key. Type that and tap (or click) OK. The message will send and you are good to go.

Figure D

Figure D

K-9 Mail open with your encrypted message added.

Null error solution

If you wind up getting an OpenPGP Null error, it means you have not selected an OpenPGP for K-9. To do that, open up K-9, click the menu button in the upper right corner, click Settings | Account settings, click Cryptography, click OpenPGP Provider, select APG (Figure E - make sure to select the option without the icon), and then back out of Settings by tapping the back button (in the upper left corner) until you're in the K-9 main window.

Figure E

Figure E

Setting the OpenPGP Provider in K-9 mail.

Ready to encrypt

With these two apps installed on your Chromebook, you are ready to encrypt without having to rely on a Chrome plugin. Yes, you can use K-9 mail directly to encrypt your messages, but going through APG streamlines the process a bit and gives you slightly more control over how you work. Give this method a go and see if doesn't help make the process of encryption a bit more efficient on your Chromebook.

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