1. Signing on Linux requires a certificate manager like "kleopatra", "seahorse", "gpa" or "kgpg".

2. Open LibreOffice (e.g. "Writer" for text document):

3. Create a document (do not forget to save before going on with signing):

4. Go to signing menu:

5. Now the window where you can choose the certificate/keypair opens.

• The windows in the background can be closed using <Esc>.

6. The certificates are show for which valid information are stored in "kleopatra" (e.g. private key):

7. Select the required certificate/keypair and add a short description if wanted/needed:

8. And sign the document as final step:

9. "Close" this last window at the end:

10. The document shall now show a valid signature:

11. Close the document.

• Do not save the file again as the signature will be lost if doing so.