Once successfully created, your user certificate will be in the certificate store of your operating system or browser.
In order to integrate the certificate in e-mail programmes (also on other devices), it must first be saved as a file - in other words, exported. When you create the export file, a password is used to protect the private key in your user certificate, as well as to encrypt the export file itself. This password is necessary for a successful import into an S/MIME-compatible mail programme, because only with it can the file be decrypted again. The data carrier on which the export file is located may only be accessible to you. Of course, the same applies for the password.
If you created the certificate on Windows with Google Chrome or Internet Explorer, you will need to export your certificate from the Windows certificate store.
If you have used Firefox on Windows, Linux or MacOS to create the certificate, then the certificate must be exported from Firefox's own certificate store.
Export the certificate from the Windows certificate store
You can only export a user certificate from the Windows certificate store, if you have marked it during the import process.
(please refer Import to the Windows certificate store)
Press the key combination "Windows key + R", enter "certmgr.msc" in the opening window and press Enter.
It opens the Certificate manager from Windows. Now open the folder Own certificates and then click Certificates. Now select your personal certificate in the list (usually the only one) and open it by double-clicking.
Make sure that the message "You have a private key for this certificate" appears at the bottom of the window. Then select the page "Details",
to export your user certificate and click on "ICopy a file ".
In the Certificate Export Wizard window, click "Continue".
Choose "Yes, export private key" and confirm with "Continue".
Make sure all settings are set as shown.
If your certificate should not be stored in the Windows certificate store after the export, then also select the option "Delete private key after successful export". Confirm with "Continue".
Deselect certificate data protection in Windows 10.
In the next window, you must assign a password with which the export file is protected / encrypted. Every time you want to recover your user certificate from this file in the future, this password is required.
In Windows 10 you have to select the encryption type here. Select "AES256-SHA256".
Then Click "Weiter". In the next window select the storage location and file name. Then Click "Weiter"
In the last window, confirm the selected settings with "Complete". A last dialogue should confirm the successful export of your certificate. Now you can optionally transfer the file to other systems and import it into an S/MIME compatible mail programme.
Export the certificate from the Firefox certificate store
Click on the menu icon and select "Settings",
go to "Privacy an security", then continue to "Certificates" and click on "Show certificates" to open the certificate manager of Firefox.
In the menu "Your certificates"expand, if necessary, the list of certificates from the "Hochschule für Technik und Wirtschaft Dresden - University of Applied Sciences (FH)". Then select your certificate and click "Save",
In the window that opens, select the location and the file name for the export file.
Enter a password to protect the export file.
After assigning a password, you should receive a message about the successful export of your certificate.
Please note that the certificate remains in the Firefox certificate store and is not usually needed there. At the latest after a successful import into a mail programme, you can delete the certificate in the certificate manager from the memory.