Remove a digital signature – Adobe Acrobat XI User Manual
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Electronic signatures
Last updated 1/14/2015
For more information about signature warnings and valid and invalid signatures, see the Digital Signature Guide at
You assess the validity of a Digital Signature and Timestamp by checking the Signature Properties.
1
Set your signature verification preferences. For more information, see
Set signature verification preferences
.
2
Open the PDF containing the signature, then click the signature. The Signature Validation Status dialog box
describes the validity of the signature.
3
For more information about the Signature and Timestamp, click Signature Properties.
4
Review the Validity Summary in the Signature Properties dialog box. The summary might display one of the
following messages:
Signature date/time are from the clock on the signer's computer
The time is based on the local time on the signer’s
computer.
Signature is timestamped
The signer used a Timestamp Server and your settings indicate that you have a trust
relationship with that timestamp server.
Signature is timestamped but the timestamp could not be verified
Timestamp verification requires obtaining the
timestamp server's certificate to your list of trusted identities. Check with your system administrator.
Signature is timestamped but the timestamp has expired
Acrobat and Reader validate a timestamp based on the
current time. This message is displayed if the timestamp signer's certificate expires before the current time. To let
Acrobat or Reader accept an expired timestamp, select Use Expired Timestamps in the Signature Verification
Preferences dialog box (Preferences > Signatures > Verification: More). Acrobat and Reader display an alert message
when validating signatures with expired timestamp.
5
For details about the signer’s certificate, such as trust settings or legal restrictions of the signature, click Show Signer’s
Certificate in the Signature Properties dialog box.
If the document was modified after it was signed, check the signed version of the document and compare it to the
current version.
Remove a digital signature
You cannot remove a digital signature unless you are the one who placed it and you have the digital ID for signing it
installed.
❖
Do one of the following:
• To remove a digital signature, right-click the signature field and choose Clear Signature.
• To remove all digital signatures in a PDF, choose Clear All Signature Fields from the options menu in the
Signatures panel. (To open the Signatures panel, choose View > Show/Hide > Navigation Panes > Signatures.)
View previous versions of a digitally signed document
Each time a document is signed using a certificate, a signed version of the PDF at that time is saved with the PDF. Each
version is saved as append-only and the original cannot be modified. All digital signatures and their corresponding
versions can be accessed from the Signatures panel.
1
In the Signatures panel, select and expand the signature, and choose View Signed Version from the Option menu
.
The previous version opens in a new PDF, with the version information and the name of the signer in the title bar.
2
To return to the original document, choose the document name from the Window menu.