Operation Manual

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Electronic signatures
Last updated 4/7/2015
When you apply a certificate-based signature, Acrobat uses a hashing algorithm to generate a message digest, which it
encrypts using your private key. Acrobat embeds the encrypted message digest in the PDF, certificate details, signature
image, and a version of the document when it was signed.
Certifying and signing documents
The Sign > Work with Certificates panel lets you apply two types of certificate-based signatures. You can certify a
document attest to its content or approve a document with the Sign With Certificate option.
Certify Certify options provide a higher level of document control than Sign With Certificate. For documents that
require certification, you must certify the documents before others sign them. If a document has already been signed,
the Certify options are disabled. When you certify a document, you can control the types of changes other people can
make. You can certify with or without displaying a signature.
Sign With Certificate When you sign with a certificate, the signature is considered an approval signature.
Signatures made with the Certify or Sign With Certificate options comply with data protection standards specified by
the European Telecommunications Standards Institute (ETSI). In addition, both signature types comply with the PDF
Advanced Electronic Signature (PAdES) standard. Acrobat and Reader provide an option to change the default signing
format to a CAdES format. This option is compliant with Part 3 of the PAdES standard. The timestamp capability and
native support for long-term validation of signatures (introduced in Acrobat 9.1) is in compliance with Part 4 of the
PAdES standard. The default signing format, when set up accordingly, is compliant with Part 2 of the PAdES standard.
You can change the default signing method or format, in the Signatures panel of the Preferences dialog box. Under
Creation & Appearance, click More.
Setting up certificate-based signatures
You can expedite the signing process and optimize your results by making the following preparations in advance.
Note: Some situations require using particular digital IDs for signing. For example, a corporation or government agency
can require individuals to use only digital IDs issued by that agency to sign official documents. Inquire about the digital
signature policies of your organization to determine the appropriate source of your digital ID.
• Get a digital ID from your own organization, buy a digital ID (see the Adobe website for security partners), or create
a self-signed one. See
Create a self-signed digital ID. You can’t apply a certificate-based signature without a digital id.
Note: You cannot create self-signed digital IDs from within FIPS mode.
• Set the default signing method.
• Create an appearance for your certificate-based signature. (See Create the appearance of a certificate-based
signature)