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Digital signatures are blocks of information that
are added to electronic documents. You can use them to authenticate
the identity of the signer and verify the integrity of the document
or part of the document:
Signatures contain information that lets you determine
the owner of the signature. This information is useful for verifying
the identity of the originator of the document.
When a document is digitally signed, the signature can be
used to determine whether the document has changed since it was
signed.
Credentials are used to create digital signatures. Certificates
are used to validate digital signatures and their owners.
Digital signatures and the Signature serviceThe Signature service
supports PDF signatures and XML signatures:
The Signature
service can create PDF signatures for all PDF documents, such as
PDF documents created by using Designer or Acrobat.
The Signature service can validate XML signatures for XFA-based
PDF documents, such as PDF documents that are created by using Designer
or by the Forms service.
PDF signatures can be used
for purposes beyond the basic authentication of signer’s identity
and validating document integrity:
- Approval
Signatures:
- Used for approving document content. For example, a user
fills a form and then signs the form to approve the form data.
- Certifying signatures:
- Used for attesting to the document contents and specifying
the types of changes that are permitted for the document to remain certified.
For example, a government agency creates a form with signature fields. The
agency certifies the document, allowing users to change only form
fields and to sign the document. Users can fill the form and sign
the document. However, if users remove pages or add comments, the
document does not retain its certified status.
Certifying
signatures are also known as Modify Detection Prevention (MDP) signatures.
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