The DevExpress PDF Document API library allows you to retrieve a certificate from a hardware device (such as Windows certificate store, SmartCard, USB Token). This example demonstrates how to use a certificate stored on a user's machine. You can also adapt this solution to sign documents using certificates from any physical store.
First, you need to obtain a certificate from a Windows certificate store. In this example, the System.Security.Cryptography.X509Certificates.X509Certificate2UI class is used to display a system dialog. This dialog allows you to view and select an X.509 certificate. Create a Pkcs7Signer object and pass the retrieved certificate to the object constructor. Use this class to sign a PDF document.