Digital Signatures
Who signed this document, and has anybody changed it since? Digital signatures answer both questions inside the PDF itself, where every recipient can check them. TX Text Control .NET for Windows Forms signs PDF and PDF/A documents while it saves them, either the whole document or single signature fields, with a certificate from a file or from the Windows certificate store. The pages below lead from the concepts to certificates, visible signatures, several signers and trusted timestamps.
Signing for the first time? Digitally Sign a PDF in Getting Started creates a test certificate and signs a document from a form in a few steps.
How Signing Works in TX Text Control
Your code wraps an X.509 certificate with its private key in a DigitalSignature, and TextControl or ServerTextControl signs the whole document or named signature fields while it saves the document as PDF or PDF/A. The Building Blocks in the Overview lists the classes that take part, and How Signing Works in TX Text Control the formats and Save overloads that sign.
Find the Right Page
| If you want to | Read |
|---|---|
| Understand what a signature proves, how electronic and digital signatures differ and which parts of TX Text Control take part | Overview |
| Sign the document of the editor or a merged document, sign into memory, handle errors and verify signatures in code | Signing PDF Documents |
| Load certificates from .pfx files, let users choose one from the Windows certificate store and check them | Certificates |
| Sign signature fields, give them images and generate a signature appearance | Signature Fields and Signature Appearance |
| Sign a document for several people or with several certificates | Multiple Signatures |
| Add trusted timestamps, handle unavailable time servers and create PAdES-T signatures | Timestamp Configuration |
Where to Start
- Overview: the concepts and the building blocks.
- Certificates: a certificate to develop with and the certificates of your users.
- Signing PDF Documents or Signature Fields and Signature Appearance, depending on whether the whole document or single fields are signed.
- Timestamp Configuration: keep the signatures verifiable for years.