Adobe Acrobat 8 3D - Manual (Page 274)

267 ADOBE ACROBAT 3D VERSION 8
User Guide
The advantage of securing documents with certificates is that authors can specify unique permissions for each group
in their company. For example, authors can permit employees to sign and fill forms, and permit managers to edit text
or remove pages. When you encrypt a PDF using a certificate, you specify a list of recipients and define each
recipient’s level of access to the file—for example, whether the recipient can edit, copy, or print the file. You can
specify certificates from your list of trusted identities, from files on disk, from an LDAP server, or from the Windows
certificate store (Windows only). Be sure to include your own certificate in the list so that you are later able to open
the document.
Note: If possible, encrypt documents using certificates from third-party digital IDs. If the certificate is lost or stolen, the
issuing authority can replace it. If a self-signed digital ID is deleted, all PDFs that were encrypted using the certificate
from that ID are forever inaccessible.
If you need to encrypt a large number of PDFs, use the Batch Processing command to apply a predefined sequence,
or edit an existing sequence to add the security features you want. You can also save your certificate settings as a
security policy and reuse it to encrypt PDFs.
1 Do one of the following:
• Click the Secure button in the Tasks toolbar, choose Show Security Properties, and then choose Certificate
Security from the Security Method menu. (Use this method if you want to save your settings as a security policy.)
• Choose Advanced > Security > Certificate Encryption.
• Click the Secure button in the Tasks toolbar, and choose Certificate Encryption.
2 In the Certificate Security Settings dialog box, specify whether to save your settings as a policy or discard them
after applying (if available).
3 Select which document components to encrypt.
4 From the Encryption Algorithm menu, choose 128-bit AES or 128-bit RC4. If you select 128-bit AES, Adobe
Acrobat 7.0 or later or Adobe Reader 7.0 or later is required to open the document. Click Next.
5 Select the digital ID you want to use.
6 Create a recipient list for the encrypted PDF: Click Search to locate identities in a directory server or in your list
of trusted identities, or click Browse to locate the file that contains certificates.
7 In the Recipients list, select the recipient(s) for whom you wish to set levels of access, click Permissions, and click
OK in the Acrobat Security dialog box. Then select the levels of access. If you don’t set permissions, recipients have
full access by default.
8 Click OK to implement your settings, and then click Next. Review your settings and then click Finish.
When a recipient opens the PDF, the security settings you specified for that person are used.
See also
“About digital IDs” on page 253
“Get certificates from other users” on page 258
Change or remove encryption from a PDF
You can change or remove security settings from PDF files that you’ve encrypted.
Change encryption settings
1 Click the Secure button in the Tasks toolbar, and choose Show Security Properties.