Operation Manual

239
USING ACROBAT X STANDARD
Digital signatures
Last updated 10/11/2011
More Help topics
“Validate a timestamp certificate” on page 236
“Configure a timestamp server” on page 227
“Set signing preferences” on page 223
Add verification information at signing
1 Make sure that your computer can connect to the appropriate network resources.
2 Ensure that the preference Include Signature’s Revocation Status When Signing is still selected. (Preferences >
Security > Advanced Preferences > Creation tab.) This preference is selected by default.
3 Sign the PDF.
If all the elements of the certificate chain are available, the information is added to the PDF automatically. If a
timestamp server has been configured, the timestamp is also added.
Add verification information after signing
In some workflows, signature validation information is unavailable at signing, but can be obtained later. For example,
a company official may sign a contract using a laptop while traveling by air. The computer cannot communicate with
the Internet to obtain timestamping and revocation information to add to the signature. When Internet access is
available later, anyone who validates the signature can add this information to the PDF. All subsequent signature
validations can also use this information.
1 Ensure that your computer can connect to the appropriate network resources, and then right-click the signature in
the PDF.
2 Choose Add Verification Information.
Information and methods used to include this long term validation (LTV) information in the PDF comply with Part
4 of the ETSI 102 778 PDF Advanced Electronic Signatures (PAdES) standard. For more information, see
blogs.adobe.com/security/2009/09/eliminating_the_penone_step_at.html. The command is unavailable if the
signature is invalid, or is signed with a self-signed certificate. The command is also unavailable in case the verification
time equals the current time.
Manage trusted identities
A digital ID includes a certificate with a public key and a private key. Participants in signing and certificate security
workflows exchange the public part (the certificate) of their digital ID. Once you obtain someone’s certificate and add
it to your trusted identities list, you can encrypt documents for them. There may be instances when the certificate does
not already chain up to a trust anchor that you have specified. In such cases, you can set the certificate’s trust level so
that you can validate the owner’s signature. Understanding what a trusted identity is and how trust levels are set lets
you streamline workflows and troubleshoot problems. For example, you can add trusted identities in advance and
individually set the trust for each certificate. In enterprise settings, your trusted identities list may be preconfigured.
You may also be able to search a directory server for additional certificates.