Operation Manual

246
USING ACROBAT 9 STANDARD
Digital signatures
Last updated 9/30/2011
Validating signatures
Checking the validity of a signature
When signatures are validated, an icon appears in the document message bar to indicate the signature status. Further
details about the status appear in the Signatures panel and in the Signature Properties dialog box.
Third-party signature handlers can provide alternate methods of validating signatures. Check the documentation
included with your third-party digital ID.
Important: To ensure that signatures are valid when you open a PDF and that all verification details appear with the
signature, set your verification preferences in advance. (See
“Set signature verification preferences” on page 247.)
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 User Guide
(PDF) at
www.adobe.com/go/learn_acr_security_en.
More Help topics
“Verify information on a certificate” on page 223
“Get certificates from other users” on page 220
Validate a signature manually
You can assess the validity of a digital signature by checking the signature properties.
1 Set your signature verification preferences. For more information, see “Set signature verification preferences” on
page 247.
2 Open the PDF containing the signature, right-click the signature, and then choose Validate Signature. The
Signature Validation Status describes the validity of the signature.
3 Click Signature Properties, and do the following:
• If the status is unknown, click the Signer tab, and then click Show Certificate to view the details of the certificate. If
you’re working with self-signed digital IDs, confirm that the certificate details are valid. If the certificate isn’t valid,
request a valid certificate from the signer. Click OK.
• Click the Date/Time tab to verify the timestamp, if needed.
• Click the Legal tab to learn more about the legal restrictions of the signature. In the Legal tab, click View Document
Integrity Properties to check if it contains items that could alter its appearance.
If the document was modified after it was signed, check the signed version of the document and compare it to the
current version.
More Help topics
“Validate a timestamp certificate” on page 249
“Sign in Preview Document mode” on page 244
“View previous versions of a signed document” on page 249