The digital signature of a PDF document can be checked from the original file only.
If the file is changed, the digital signature disappears. Students may print a paper copy, but the signature is not valid on the printed document. Parties that request these documents should not accept paper copies without the verified electronic document.
To check the validity of a digitally signed PDF document:
- Open the PDF file with Adobe Acrobat Reader and then its Signature Panel.
- Check the certificate information. A PDF document from the University of Eastern Finland is digitally signed when the Signature Panel shows the following text:
Rev. 1: Signed by CSC-IT Center for Science Ltd
Signature is valid:
Source of Trust obtained from Adobe Approved Trust List (AATL).
Document has not been modified since this signature was applied
Signer's identity is valid
Signing time is from the clock on the signer's computer.
Signature is not LTV enabled and will expire after 2021/01/23 15:44:55 +02´00´
Signature Details
Certificate Details...
Last Checked: yyyy.mm.dd time timezone
Field: Signature1 (invisible signature)
In case the information in the Signature Panel differs from the above (e.g. claims that "Signature has problems") this could be caused by the settings in your Acrobat Reader.
If the Signature Panel is unavailable, ask the student for the certified file.