Certify a pdf, Timestamp a document, Validate a digital signature – Adobe Acrobat XI User Manual
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Electronic signatures
Last updated 1/14/2015
Certify a PDF
When you certify a PDF, you indicate that you approve of its contents. You also specify the types of changes that are
permitted for the document to remain certified. For example, suppose that a government agency creates a form with
signature fields. When the form is complete, the agency certifies the document, allowing users to change only form
fields and sign the document. Users can fill the form and sign the document. However, if they remove pages or add
comments, the document doesn’t retain its certified status.
You can apply a certifying signature only if the PDF doesn’t already contain any other signatures. Certifying signatures
can be visible or invisible. A blue ribbon icon
in the Signatures panel indicates a valid certifying signature. A digital
ID is required to add the certifying digital signature.
1
Remove content that may compromise document security, such as JavaScripts, actions, or embedded media.
2
Choose Sign > Work With Certificates to open the panel.
3
Click one of the following options:
Certify (Visible)
Places a certified signature in either an exiting digital signature field (if available) or in the
location you designate.
Certify (Not Visible)
Certifies the document, but your signature appears only in the Signatures panel.
4
Follow the onscreen instructions to place the signature (if applicable), specify a digital ID, and set an option for
Permitted Actions After Certifying.
Note: If you enabled the When Signing: View Documents In Preview Mode in the Signature preferences, click Sign
Document in the document message bar.
5
Save the PDF using a different filename than the original file, and then close the document without making
additional changes. It is a good idea to save it as a different file so that you can retain the original unsigned
document.
Timestamp a document
Acrobat provides users with the capability to add a document timestamp to a PDF without also requiring an identity-
based signature. A timestamp server is required to timestamp a PDF. (See
.) A timestamp
assures the authenticity and existence of a document at a particular time. These timestamps are compliant with the
timestamp and revocation features described in Part 4 of ETSI 102 778 PDF Advanced Electronic Signatures (PAdES)
standard. Users of Reader X (and later) can also timestamp a document if the document includes appropriate Reader
Enabling features.
For more information on PAdES, see
1
Open the document to which you want to add a timestamp.
2
Choose Sign > Work With Certificates > Time Stamp Document.
3
In the Choose Default Timestamp Server dialog box, select a default timestamp server from the list, or add a new
default timestamp server.
4
Click Next, and then save the document with the timestamp.
Validate a digital signature
If the signature status is unknown or unverified, validate the signature manually to determine the problem and possible
solution. If the signature status is invalid, contact the signer about the problem.