Operation Manual

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Electronic signatures
Last updated 4/7/2015
❖ Choose View > Show/Hide > Navigation Panes > Signatures, or click the Signature Panel button in the document
message bar.
You can right-click a signature field in the Signatures panel to do most signature-related tasks, including adding,
clearing, and validating signatures. In some cases, however, the signature field becomes locked after you sign it.
Validate a certificate-based 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.
For more information about signature warnings and valid and invalid signatures, see the Digital Signature Guide (PDF)
at
www.adobe.com/go/learn_acr_security_en.
You assess the validity of a certificate-based 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.