SignImage.cs

/// <summary>
/// Sign the image data with the given certificate and write to the xmlFilePath
/// </summary>
/// <param name="imageBuffer">Image data to sign</param>
/// <param name="certificateBuffer">Private key certificate byte[]</param>
/// <param name="certPassword">Private key certificate Password</param>
/// <param name="xmlFilePath">The path to save the signed XML</param>
public static void SignImage(byte[] imageBuffer, byte[] certificateBuffer,string certPassword, string xmlFilePath)
{
    var certificate = new X509Certificate2(certificateBuffer, certPassword);

    var xmlDocumentBuffer = SerializeImageToXML(imageBuffer);

    SignXMLDocument(xmlDocumentBuffer, certificate, xmlFilePath);
}