Adobe 22002484 User Guide - Page 254

USING ACROBAT 9 STANDARD 249 Digital signatures Display the Signatures panel ❖ Choose View > Navigation Panels > 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 timestamp certificate Review the Validity summary section of the Signature Properties dialog box for the validity status of a timestamp certificate. 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 You may need to establish a trust relationship with the timestamp server. You can establish a trust relationship using the following instruction, but first you need to make sure you are familiar with the timestamp server and trust it. Check with your system administrator. To validate a signature that contains a timestamp, you must obtain the certificate for the timestamp server and add it to your list of trusted identities. Otherwise, the timestamp appears as unverified, and you must validate the timestamp manually. 1 Click the Signatures button in the navigation pane, select the signature, and choose Validate Signature from the options menu . 2 Click the Signature Properties button in the Signature Validation Status dialog box. 3 In the Signature Properties dialog box, click the Date/Time tab to view the timestamp authority, and then click the Show Certificate button. (This button appears in the Date/Time tab only if the signer used a timestamp server.) 4 In the Certificate Viewer, click the Trust tab to determine if the timestamp certificate is trusted. If it isn't trusted but you do trust it, click Add To Trusted Identities. If a certificate for the timestamp server isn't listed, request one from the signer. More Help topics "Securing documents with certificates" on page 218 View previous versions of a signed document Each time a document is signed, a signed version of the PDF is saved with the PDF. Each version is saved as appendonly and the original cannot be modified. All 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. Last updated 9/30/2011