digital signatures - how can i change icon of a signature and text " valid signature"

[Andrei “FAD” Fulea]

Hello,

I have 2 questions : 

1. how can I change/control this green valid icon ? 
2. on the top of the icon, is the text " valid signature ", also, I want to change/control it with another text or remove

I'm using .net core and Syncfusion.Pdf.Net.Core version 20.3.0.56

Thank you

[Irfana Jaffer Sadhik]

We cannot modify the existing digitally signed PDF document appearance, if we do it will tamper the signature.  We can able to customize the signature appearance. 

Please use the below code snippet to achieve the same requirement on your end:

//Creates a new PDF document.

PdfDocument document = new PdfDocument();

//Adds a new page.

PdfPageBase page = document.Pages.Add();

//Create PDF graphics for the page.

PdfGraphics graphics = page.Graphics;

//Creates a certificate instance from PFX file with private key.

PdfCertificate pdfCert = new PdfCertificate(@"PDF.pfx", "password123");

//Creates a digital signature.

PdfSignature signature = new PdfSignature(document, page, pdfCert, "Signature");

//Sets an image for signature field.

PdfBitmap signatureImage = new PdfBitmap(@"signature.png");

//Sets signature information.

signature.Bounds = new RectangleF(0,0,200,100);

signature.ContactInfo = "[e-mail]";

signature.LocationInfo = "Honolulu, Hawaii";

signature.Reason = "I am author of this document.";

//Create appearance for the digital siganture.

signature.Appearance.Normal.Graphics.DrawImage(signatureImage, signature.Bounds);

//Save the document.

document.Save("DigitalSignature.pdf");

//Close the document.

document.Close(true);

Follow the below links for more information,

https://help.syncfusion.com/file-formats/pdf/working-with-digitalsignature#drawing-textimage-in-the-signature-appearance