User Guide

Providing Document Security
Digitally Signing Adobe PDF Documents
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96 Acrobat SDK User’s Guide
Note that the Standard security handler, used for password encryption of documents, is not
JavaScript enabled in general. In Acrobat 7.0, encryption using Standard security is possible
using predefined policies.
Also, in Acrobat 7.0, the Adobe.APS handler can be used for encryption via the
encryptUsingPolicy method. This handler also makes a directory available via the
directory services, but as no certificates are returned from this directory, it is of limited
general use.
For more information, see the Acrobat JavaScript Scripting Reference.
Digitally Signing Adobe PDF Documents
A digital signature, like a conventional handwritten signature, identifies the person signing
a document. Unlike traditional signatures on paper, however, each digital signature stores
information about the person signing a document. Signatures help prevent unwanted
changes to a PDF document. For example, an author may not want a PDF document with
company letterhead to be changed after it is signed.
The first signature in a document is called the author signature. When you add the first
signature to a document, you have the option of certifying the document. Certifying a
document lets you attest to its contents and specify the types of changes allowed for the
document to remain certified. Changes to the document are detected in the Signatures tab.
Subsequent signatures to the document are called ordinary signatures.
To sign a document, you must select a digital ID, which contains the signature information
that you can share with other users in a certificate. You can create a self-signed digital ID, or
you can obtain a digital ID from a third-party provider. Using certificates, other users can
validate your signatures, and you should validate the signatures of others.
Signing Adobe PDF Documents
An author of a PDF document can simply add a signature to indicate approval.
Alternatively, a PDF document can be signed more than once and by more than one
person. For example, the author can save a PDF document containing form fields as a
certified document, allowing only form fields to be filled in. When another user opens the
PDF document, a message indicates whether the certification is still valid. This user can
then fill out the form and sign the document when finished.
To add a signature to a PDF document using Acrobat JavaScript:
● Create a signature field
● Choose a security handler
● Invoke the field’s signatureSign method
From a plug-in, you can sign a PDF document using the PubSec and DigSig APIs.