Preparation

You will need the following:

• Administrator access to your Synology NAS. I’m using a Synology DS918+ running DSM 6.2.4-25556.
• Your Private Key from your Public/Private Key Pair. It should have the file extension of .key and when opened in a text editor, should look like the following:

  -----BEGIN PRIVATE KEY-----
  <base 64 encoded private key>
  -----END PRIVATE KEY-----

• Your Certificate Signing Request. You may have generated this using OpenSSL. It contains details about your domain, your organisation, and also contains the Public Key from your Public/Private Key Pair. It should have a file extension of .csr and look like this:

  -----BEGIN CERTIFICATE REQUEST-----
  <base 64 encoded certificate request>
  -----END CERTIFICATE REQUEST-----

• The Certificate Authority file. This should have a file extension of .ca and look like this:

  -----BEGIN CERTIFICATE-----
  <base 64 encoded certificate>
  -----END CERTIFICATE-----
  -----BEGIN CERTIFICATE-----
  <base 64 encoded certificate>
  -----END CERTIFICATE-----

  Each of these files are in PEM format, which is just a Base64 encoded binary file so that they can be read as text files. Decoding these files will result in mainly non-printable characters. For more info have a read about Privacy-Enhanced Mail.

Installation

1. Log into the Synology Disk Station as an administrator.
2. Go to Control Panel > Security > Certificate
   
3. Click Add > Add a new certificate > Import certificate. Provide a description in the Description field.
4. On the Import Certificate Files screen, click Browse and select each of the required files and then click OK:
   
5. The Web Server will restart and a few minutes later you will land back at the Synology Web Interface dashboard. You may need to log in again.
6. The wildcard certificate should now be installed. Check your browser. In most browsers, click on the padlock in the address bar and then click View Certificate: