Adobe READER 8 - Digital Signatures

ADOBE READER 8
User Guide
82
Create a self-signed digital ID
A digital ID is required to sign documents. Self-signed digital IDs created from Reader may be adequate for many
situations. See the Adobe website for information on acquiring a digital ID from Adobe security partners.
1 Choose Document > Security Settings.
2 Select Digital IDs, and click Add ID.
3 Select Create A Self-Signed Digital ID For Use With Acrobat.
4 Follow the on-screen instructions to set up the self-signed digital ID.
Digital signatures
About digital signatures
A digital signature, like a conventional handwritten signature, identifies the person signing a document. Unlike a
handwritten signature, a digital signature is difficult to forge because it contains encrypted information that is
unique to the signer and easily verified.
Most digital signatures are referred to as approval signatures.SignaturesthatcertifyaPDFarecalledcertifying signa-
tures. Only the first person to sign a PDF (most often, the author) can add a certifying signature. A certifying
signature attests to the contents of the document and allows the signer to specify the types of changes allowed for the
document to remain certified. Changes to the document are detected in the Signatures panel.
To sign a document, you must obtain a digital ID or create a self-signed digital ID in Reader. The digital ID contains
a private key that is used to add the digital signature, and a certificate that you share with those who need to validate
your signature. When you apply a digital signature, Reader uses a hashing algorithm to generate a message digest,
which it encrypts using your private key. Reader embeds the encrypted message digest in the PDF, along with details
from your certificate, a visual representation of your signature, and a version of the document at the time it was
signed.
Note: For the latest information about digital signatures, choose Help > Online Support > Knowledge Base to open the
Adobe Acrobat support page on the Adobe website, and then search for “digital signatures.”
See also
“About digital IDs” on page 87
Create the signature appearance
You can set the appearance of your digital signature by selecting options in the Security Preferences. For example,
you can include an image of your handwritten signature, a company logo, or a photograph. You can also create
alternatesignatureappearancesthatyouusefordifferentpurposes.Forsome,youmaywanttoprovideagreaterlevel
of detail.
A signature appearance can also include information that helps others verify your signature, such as certificate
revocation status, reasons for signing, contact information, and more. By selecting these preferences, you add
options to the Sign Document dialog box that appears each time you sign a PDF.
1 If you want to include an image of your handwritten signature in the digital signature, scan your signature and
save it as an image file. Place the image in a document by itself, and convert the document to PDF.