Digital Signatures in PDFs

Create, certify, and validate digital signatures in PDF documents using the PDF SDK and the Conversion Service. Support for multiple cryptographic providers.

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Sign documents like you’re in the room

PDF SDK

Authenticate documents with digital signatures

The PDF SDK offers granular controls over digital signatures in a variety of PDF formats

Authenticate the signer of a document
Ensure a document hasn’t been tampered with
Prove a document has existed since a certain date

Start implementing digital signatures for your document pipeline with the Pdftools SDK

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Authenticate documents with digital signatures

Conversion Service

Safely sign archived PDF/A files

The dedicated “Sign PDF” workflow is engineered specifically for signing PDF/A documents without removing existing signatures

Strictly for archived (PDF/A) documents
Does not remove existing signatures
Signing must happen after conversion

The Conversion Service supports automated batch signing for PDF/A-2 and PDF/A-3 documents

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What are digital signatures?

Electronic signatures ≠ digital signatures

Electronic signatures and digital signatures should not be used interchangeably. Electronic signature is the umbrella term, while digital signatures are a subtype with specific technical and legal requirements, following strict regulations such as eIDAS (European Union) or ZertES (Switzerland). Electronic signatures have no legal significance, but digital signatures can be legally valid while having the advantage of not needing to print something or be physically present to sign.

Digital signatures are created by applying a cryptographic algorithm to a document. It works using a key pair. Each key is a large numerical value:

A private key is kept secret by the signer and used to generate the signature
A public key which is shared openly and is used by anyone to verify the signature

Electronic signatures ≠ digital signatures

Pdftools supports various cryptographic providers

Use local or remote certificates, external cryptographic providers, or the built-in one

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Digital signatures in the Pdftools SDK

PDFs support digital signatures natively. A signed PDF embeds signature, certificate, and timestamp directly in the file. The Pdftools SDK lets you manage digital signatures in PDF documents with granular control over the process.

Sign PDFs / Document Approval

Record the identity of the signer and confirm that content wasn’t changed since signing. A document can carry multiple document approval signatures.

Certify PDFs / Modification Detection and Prevention

A document certification or MDP signature records the identity of the author and only allows specific changes, e.g. filling forms, annotations, approval signatures.

Time-stamp PDFs

A time stamp provides evidence that a document has existed at a specific time and hasn’t been changed since. You can also ise time-stamp signatures to “re-sign” a document.

Validate signatures

Validate any signatures that have previously been added to approve or certify a PDF document against trusted sources. You can also add certificates for offline validation.

Visual signature

Configure a visual appearance for a signature using XML or JSON, which can contain text, images, and pages of PDFs. A signature’s visual appearance can take the form of a signature, stamp, etc.

Conversion first, signature second

The conversion from PDF to PDF/A removes any signatures previously present in the file. Therefore, it is better to always archive files to PDF/A format before applying any digital signatures.

Use cases for digital signatures in PDFs

Highly regulated industries often explicitly require signatures that prove integrity and identity, and the information needs to be clear and easily accessible for eventual audits

Banking

Signing legally binding contracts, such as loan agreements or account-opening forms, without physical presence being necessary

Insurance

Proving policy documents haven’t been altered and still represent the exact terms the customer has agreed to

Government

Verifying authenticity without physical stamps or seals, e.g. permits, licenses, or official correspondence

Start signing your documents the right way with Pdftools

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