DigitalSignature class

Digital signature in signed file.

public class DigitalSignature : IDigitalSignature


DigitalSignature(X509Certificate2)Creates a new DigitalSignature object with the specified certificate.
DigitalSignature(string, string)Creates a new DigitalSignature object with the specified certificate file path and password.


Certificate { get; }Certificate object that was used to sign the document. Read-only X509Certificate2.
Comments { get; set; }The purpose of signature. Read/write String.
IsValid { get; }If this digital signature is valid and the document has not been tampered with, this value will be true. Read-only Boolean.
SignTime { get; }The time when the document was signed. Read-only DateTime.


The following example demonstrates how to add digital signature from a PFX certificate in PowerPoint Presentation.

// Initialize Presentation instance
using (Presentation pres = new Presentation())
    // Create DigitalSignature object with PFX file and PFX password
    DigitalSignature signature = new DigitalSignature("testsignature1.pfx", @"testpass1");
    // Comment new digital signature
    signature.Comments = "Aspose.Slides digital signing test.";
    // Add digital signature to presentation
    // Save presentation
    pres.Save("SomePresentationSigned.pptx", SaveFormat.Pptx);

The following sample code demonstrates how to validate digital signature of PowerPoint Presentation.

// Initialize Presentation instance
using (Presentation pres = new Presentation("SomePresentationSigned.pptx"))
    if (pres.DigitalSignatures.Count < 0)
        bool allSignaturesAreValid = true;
        Console.WriteLine("Signatures used to sign the presentation: ");
        // Check if all digital signatures are valid
        foreach (DigitalSignature signature in pres.DigitalSignatures)
            Console.WriteLine(signature.Certificate.SubjectName.Name + ", "
                    + signature.SignTime.ToString("yyyy-MM-dd HH:mm") + " -- " + (signature.IsValid ? "VALID" : "INVALID"));
            allSignaturesAreValid &= signature.IsValid;
        if (allSignaturesAreValid)
            Console.WriteLine("Presentation is genuine, all signatures are valid.");
            Console.WriteLine("Presentation has been modified since signing.");

See Also