Install S/MIME email encryption certificate on Android

Step 1: Install Maildroid and Crypto Plugin

Maildroid works with IMAP mail servers and has actively-supported S/MIME encryption capabilities. Install the app via the app store or these links:

https://play.google.com/store/apps/details?id=com.maildroid

https://play.google.com/store/apps/details?id=com.flipdog.crypto.plugin

There is also an add-free paid version called Maildroid Pro.

Step 2: Private Certificate Installation

After installing Maildroid and setting up your email account, copy your private certificate file (ending in .p12) to the device. This can be done via USB-connection or by sending and saving the file as attachment.

Next open Crypto Plugin > Import Certificate. Choose the *.p12 file. Enter the password.

Last open Crypto Plugin > Settings > Password Cache and set to Forever.

Step 3: Maildroid Setup

In Maildroid the following settings are recommended:

  • Maildroid > Settings > Encryption Plugins > Sign by default? – YES
  • Maildroid > Settings > Encryption Plugins > Show crypto bar – YES

Step 4: Public Certificate Installation

To send encrypted emails to other users, their public key needs to be installed in the app Crypto Plugin.

There are 2 methods to install a public certificate:

Method 1: Via signed Email (recommended)

  • Open a signed email and click “Signed. Click to verify”

    /Users/manu/Documents/SMIME/instructions/screenshots/14449842832691.jpg

  • On the next screen click the “I”-icon on the left.
    /Users/manu/Documents/SMIME/instructions/screenshots/14449842831670.jpg
  • Then click “Certificate Path”. Now the certificate should be added to Crypto Plugin and available for use.
    /Users/manu/Documents/SMIME/instructions/screenshots/14449842838892.jpg
  • Open Crypto Plugin (the app) to confirm the email address is listed under “S/MIME Certificates”. If not, repeat the last few steps.

Method 2: Via .cer file

  • Copy the public certificate file(s) to your Android device by Email or USB.
  • Open “Crypto Plugin”
  • Select “Import Certificate”