LibreOffice 7.1 Help
LibreOffice can digitally sign an existing PDF document.
བཀའ་ཚིག་ལ་བཅར་འདྲི་...
Choose File - Digital Signatures - Sign Existing PDF.
The file opens in LibreOffice Draw in read only mode.
Sign the PDF document as usual.
འབྲེལ་ཡོད་གཙོ་དོན་
About Digital Signatures