Digital signatures overview

Learn how digital signatures in Acrobat help verify a document’s authenticity, protect its integrity, and support compliance.

A digital signature is a secure, encrypted way to sign and verify PDF documents using a certificate-based digital ID. It confirms the signer’s identity, ensures authenticity, and protects the document from unauthorized changes. Acrobat supports both self-created digital IDs and certificates from trusted third-party providers, helping maintain document integrity and meet industry compliance standards.

A certificate-based digital signature uniquely identifies the signer and uses encryption to safeguard the document. It requires a digital ID, which contains a private key for signing and a certificate for verifying the signature.

Key features and capabilities

• Sign and certify PDFs with certificate-based IDs.
• Validate signatures and track document changes.
• Set permissions to allow form-filling or comments while restricting editing.
• Use timestamps for long-term validation.

Acrobat provides the following two digital signature options:

• Digitally sign a document as an approval signature.
• Certify a document to control modifications and approve content. Certification can be visible or invisible, but it must be applied before other signatures.

Security and compliance standards

Key features of Acrobat digital signature and security capabilities include:

• Compliance with ETSI, PAdES, and CAdES standards for data protection.
• Support for XML data signatures for signing XFA forms, following the W3C XML-Signature standard for integrity, authentication, and non-repudiation. XML signatures have two states: valid or invalid. The invalid state is triggered by any content modification.
• Access to Adobe LiveCycle Rights Management (ALCRM) servers to enable centralized access policies, manage user permissions, and support document auditing, with policies based on recipient or LDAP user lists.
• Support for storing password-protected Digital IDs in PKCS #12 files, smart cards, tokens, or the Windows certificate store. Signature handler in Acrobat accesses IDs from various locations, but they must be registered for use.

Alternatives for organizations without certificate-based signatures

Sign up for Adobe Acrobat Sign online to easily send, sign, and manage PDFs, Word documents, and more. Adobe securely hosts the service, so there’s no need for your IT team to set up or maintain e-signature infrastructure.

Resources

• Adobe Approved Trust List: The Adobe Approved Trust List (AATL) is a program that allows millions of users worldwide to create digital signatures that are trusted whenever the signed document is opened in Acrobat or Reader software. Check out the current members.
• Adobe Security and Privacy Portal: A good first stop for all things security and privacy at Adobe.
• Certified Document Services: Certified Document Services (CDS) was the predecessor to the AATL.
• Content Security Library: Extensive documentation on Adobe certificate signature administration.
• Managing Digital IDs: Help pages for digital ID management.