Unfortunately, the documentation for certificate installation located here https://www.microfocus.com/documentation/iprint/iprint-4/iprint_admin/app_config.html#certificates is missing some information and is unusable as is.

Here are instructions that can be used to manually create the files needed to install a 3rd party certificate.  This was done on iPrint Appliance version 4.2 using a Digicert certificate.  As always, create a snapshot and/or backup prior to taking these steps.  They work fine for me, but I am not responsible for any issues you run into while following them.

1. Create a directory on the appliance from which to run commands and to hold the files you create.

2. Create your key file (enter a passphrase when prompted).

openssl genrsa -des3 -out your_key_name.key 2048

3. Create your CSR (follow the prompts).

openssl req -new -key your_key_name.key -out your_csr_name.csr

4. Upload your CSR to your certificate provider and download the certificate and CA file.  (If format options are offered, Apache works.)

5. Create the key file to upload to the appliance.

openssl rsa -in your_key_name.key -out your_public_key_name.key

6. Login to the appliance and go to Manage iPrint Appliance > Certificates and delete the existing third party certificate.  Services will restart.

7. Relogin to the appliance (this may require that you delete browser security policies for this site due to an HSTS error) and go to Manage iPrint Appliance > Certificates > Options > Upload certificates.  Upload the CA file and cert you received from your certificate provider along with the your_public_key_name.key file.  Enter a passphrase when prompted and choose Upload.  Services will restart.

8. Relogin to the appliance and go to Manage iPrint Appliance > Certificates and verify that the certificate lists the correct information.