A few weeks ago I was looking for a guide on setting up S/MIME email encryption on my Mac and on my iPhone. I found this guide on End-to-End Email Encryption with S/MIME to be really helpful.
The guide was great. All except one part: "Configuring S/MIME on iOS (easiest way)." The article instructs you to email your private certificate to yourself. Yes, this is the easy way to install a certificate on your iPhone, but it is not the most secure. I didn't feel comfortable doing this so I decided to install the certificate and private key via USB.
This guide will show you how to install your S/MIME certificate and key on an iPhone (or iPad) using Apple's Configurator software via USB connection.
Download Apple Configurator
Apple has an application that can be used to manage and deploy settings to one or more devices. It is called Apple Configurator and is available for free from their App Store.
Add Your Certificate
- Launch Apple Configurator and you should see a window that looks something like this.
- Click on Prepare at the top and then on Setup. At the bottom of this window click on Configure Settings.
- Select Certificates from the list on the left and click on Configure in the window on the right.
- Browse your computer for your .p12 certificate file and click Open. You should see something like this.
- If you exported your .p12 certificate with a password, enter it in the box to help automate the installation.
- Finally click Save.
At this point you should plug in your iPhone via USB and click on the Prepare button at the bottom of the window. This will add the certificate you selected to your iPhone. During the installation it may ask you to enter a password on your iPhone if you password protected your .p12 file during export.
At this point you can jump back to the article I mentioned above and continue the S/MIME setup on your iPhone. Start with the section titled "Sending Encrypted Mail on iOS".