# Digital Signatures > Add PDF signing to a WPF application: DigitalSignature and SaveSettings, certificates from PFX files or the Windows store, signature fields and timestamps. - **Product:** TX Text Control .NET for WPF - **Section:** Documentation - **Kind:** Topic - **Path:** TX Text Control .NET for WPF > Digital Signatures - **695 words** - **Web URL:** https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/ - **LLMs URL:** https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/llms.txt - **LLMs-Full URL:** https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/llms-full.txt --- A digital signature turns a PDF document into evidence: of who signed it, and that it's unchanged since. TX Text Control .NET for WPF creates such signatures when it saves a document as PDF or PDF/A, for the whole document or for single signature fields, with a certificate from a *.pfx* file or the user's Windows certificate store. Developers who add signing to a WPF application find the concepts, the handling of certificates, visible signatures, several signers and trusted timestamps in the pages below. The quickest start is [Digitally Sign a PDF](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/getting-started/pdf/sign/llms-full.txt) in Getting Started: a test certificate and a signed document from a button in *MainWindow.xaml*. ### How Signing Works in TX Text Control A `DigitalSignature` wraps an X.509 certificate, and the `SaveSettings` of a PDF or PDF/A save apply it: to the whole document, invisibly, or to named signature fields, each with its own certificate and image. The [Overview](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/overview/llms-full.txt) explains both ways and the classes that take part. ### Find the Right Page | If you want to | Read | |---|---| | Know what a signature proves, how electronic and digital signatures differ and which classes take part | [Overview](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/overview/llms-full.txt) | | Sign the editor's document or a merged document, sign into memory, handle errors and verify signatures in code | [Signing PDF Documents](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/signing/llms-full.txt) | | Load certificates from *.pfx* files or the Windows certificate store, let users choose one and check it | [Certificates](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/certificates/llms-full.txt) | | Sign signature fields, set their images and generate a signature appearance | [Signature Fields and Signature Appearance](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/signature-fields/llms-full.txt) | | Sign one document for several people or with several certificates | [Multiple Signatures](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/multiple/llms-full.txt) | | Add trusted timestamps, cope with unavailable time servers and create PAdES-T signatures | [Timestamp Configuration](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/timestamps/llms-full.txt) | ### Recommended Order 1. [Overview](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/overview/llms-full.txt): concepts and classes. 2. [Certificates](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/certificates/llms-full.txt): the certificate to develop with and your users' certificates. 3. [Signing PDF Documents](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/signing/llms-full.txt) for an invisible signature, or [Signature Fields and Signature Appearance](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/signature-fields/llms-full.txt) for visible ones. 4. [Timestamp Configuration](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/timestamps/llms-full.txt): signatures that stay verifiable after the certificate expires. ### Related Sections - [Signature Fields](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/document-editor/signature-fields/llms-full.txt) in Document Editor: signature fields and signer data in the editor. - [PDF Processing](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/pdf/llms-full.txt): PDF/A, passwords and forms. - [Certificate and Private Key Handling](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/security/certificates/llms-full.txt) in Security: keep certificates and keys safe. - [Digital Signature Examples](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/examples/digital-signatures/llms-full.txt): samples and blog articles with code. --- ## In This Section - [Certificates](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/certificates/llms-full.txt): Load signing certificates in a WPF application from PFX files or the Windows store, open X509Certificate2UI with WindowInteropHelper and check validity. - [Multiple Signatures](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/multiple/llms-full.txt): Collect signatures from several people in a WPF application and sign all signature fields in one save, with separate certificates and optional timestamps. - [Overview](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/overview/llms-full.txt): What a PDF signature proves and what it doesn't, electronic and digital signatures, and the WPF parts: DigitalSignature, SignatureField and the ribbon tabs. - [Signature Fields and Signature Appearance](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/signature-fields/llms-full.txt): Give each named field of a WPF TextControl its own DigitalSignature, pick its SignatureImage in an OpenFileDialog, set its export format and draw an SVG stamp. - [Signing PDF Documents](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/signing/llms-full.txt): Save the WPF TextControl document or a merged DOCX template as a signed PDF: SaveSettings.DigitalSignature, byte arrays, errors and signature verification. - [Timestamp Configuration](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/timestamps/llms-full.txt): Set up trusted RFC 3161 timestamps in WPF: the timeServerURL parameter, fallback time servers, an offline computer, signature fields and PAdES-T profiles. --- ## Nearby - **Previous:** [Passwords and Access Permissions](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/pdf/passwords/llms-full.txt) - **Next:** [Overview](https://docs.textcontrol.com/tx-text-control-dotnet-wpf/digital-signatures/overview/llms-full.txt)