Document Locking; Document Defensibility - Adobe 22002486 User Manual

Acrobat 9 Family of Products
Security Feature User Guide
Because certification is designed to carry more legal weight than an uncertified document, greater
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attention to the content and process is typically warranted.
Certification signatures are automatically validated even if the application preference to automatically
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validate signatures is turned off.

Document Locking

Certification limits what a recipient can do with a document. Some actions are locked automatically, and
some are locked by the certifier. For example, during certification the signer can choose from the following
options:
No changes allowed
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Form fill-in and digital signatures
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Annotations, form fill-in, and digital signatures
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General editing, adding or removing pages, and so on are automatically prevented. Any changes that are
explicitly locked by the certifier or automatically prohibited by the application invalidate the certifier's
signature and revokes the document's certification.

Document Defensibility

Acrobat has a notion of a document's defensibility which is defined by the features that appear in the legal
attestation dictionary, described in Section 8.7.4 of the PDF Reference manual. Note that aside from when a
signer is certifying, Acrobat does not actively inform the user about the document's legal defensibility.
In any case, a document's legal defensibility improves if it does not contain content that threatens the
signer's ability to see what they are signing as well as their ability to certify that what the document
recipient sees is the same as that which was certified. Such content includes JavaScript, multimedia, and so
on. It is the certifier's responsibility to either remove that content or attest to the fact that such content
should be retained.
Hazardous content is revealed to users in two ways:
Acrobat helps the signer identify such content by scanning the document during the certification
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signing process. The signer is given the option to embed an attestation in the document about that
content that explains why it is present. This behavior is unique to certification signatures and does not
apply to approval signatures.
Document recipients use the View Document Integrity Properties button to launch the same
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content scanning process that was automatically launched when the certifier signed. If the document
is certified, the process generates a report that includes the certifier's attestation, if any. Content that
has been explicitly trusted by the certifier also appears on the signature tab under Trusted Content
(Figure 63).
Signing Documents
Signing With a Certification Signature 91