I want to digitally archive signed documents.
With a digital signature the digital document is legal, this isn't the case with a physical print. Documents you want to keep, or are required to keep must be saved digitally. A signature expires after a maximum of 3 years. After this date the signature will show an error unless a timestamp was used. This guarantees the signing date of the document and means that the signature is also valid when the certificate has expired: the timestamp shows that the signature was valid when the document was signed.