Embedding Multiple Signatures in PDFs with C# and .NET

In the modern world of digital technology, the ability to add electronic signatures to PDF documents is becoming increasingly important. This not only simplifies the document approval process, but also significantly speeds up the workflow. In this article, we will look at how you can add multiple signatures to PDF files using the C# programming language and platform.NET using SautinSoft.Pdf components.

This allows you not only to insert signatures, but also to customize their appearance, as well as add additional data such as location, reason for the signature and date.

The following example shows how you can add multiple signatures to a PDF document by following a few steps:

  1. Add SautinSoft.PDF from NuGet.
  2. Load the PDF document.
  3. Add a signature field. Create and customize a signature: author, reason, location, date.
  4. Add an additional signature field. Create and configure a new signature: author, reason, location, date.
  5. Save the PDF document.

Input file:

Output result:

Полный код

using System;
using System.IO;
using SautinSoft;
using SautinSoft.Pdf;
using SautinSoft.Pdf.Annotations;
using SautinSoft.Pdf.Content;
using SautinSoft.Pdf.Forms;
using SautinSoft.Pdf.Security;

namespace Sample
{
    class Sample
    {
        /// <summary>
        /// Add multisign in PDF.
        /// </summary>
        /// <remarks>
        /// Details: https://sautinsoft.com/products/pdf/help/net/developer-guide/add-multi-signature.php
        /// </remarks>
        static void Main(string[] args)
        {
            // Before starting this example, please get a free 100-day trial key:
            // https://sautinsoft.com/start-for-free/

            // Apply the key here:
            // PdfDocument.SetLicense("...");

            string pdfFile = Path.GetFullPath(@"..\..\..\simple text.pdf");

            var document = PdfDocument.Load(pdfFile);
            {
                // Add a signature field.
                var sig = document.Form.Fields.AddSignature(document.Pages[0], 10, 10, 250, 50);
                // Create new Signer.
                PdfSigner pdfSigner = new PdfSigner(@"..\..\..\Oliver Ekman.pfx", "1234567890");
                // Configure signer.
                pdfSigner.Timestamper = new PdfTimestamper(@"https://tsa.cesnet.cz:5817/tsa");
                pdfSigner.SignatureFormat = PdfSignatureFormat.CAdES;
                pdfSigner.SignatureLevel = PdfSignatureLevel.PAdES_B_LTA;
                pdfSigner.HashAlgorithm = PdfHashAlgorithm.SHA256;
                pdfSigner.AuthorPermission = PdfUserAccessPermissions.CommentAndFillForm;
                pdfSigner.Location = "Test workplace";
                pdfSigner.Reason = "Test";
                var im = PdfImage.Load(@"..\..\..\JPEG1.jpg");
                sig.Appearance.Icon = im;
                sig.Appearance.TextPlacement = PdfTextPlacement.TextRightOfIcon;
                // Sign PDF Document.
                sig.Sign(pdfSigner);
                // Save the PDF document. Saving is required to add the next signature. 
                document.Save();
                // Add a new signature field.
                sig = document.Form.Fields.AddSignature(document.Pages[1], 10, 10, 100, 50);
                // Create new Signer.
                pdfSigner = new PdfSigner(@"..\..\..\sautinsoft.pfx", "123456789");
                // Configure signer.
                pdfSigner.Timestamper = new PdfTimestamper(@"https://freetsa.org/tsr");
                pdfSigner.SignatureFormat = PdfSignatureFormat.CAdES;
                pdfSigner.SignatureLevel = PdfSignatureLevel.PAdES_B_LTA;
                pdfSigner.HashAlgorithm = PdfHashAlgorithm.SHA256;
                pdfSigner.Location = "Test workplace";
                pdfSigner.Reason = "Test";
                im = PdfImage.Load(@"..\..\..\JPEG2.jpg");
                sig.Appearance.Icon = im;
                sig.Appearance.TextPlacement = PdfTextPlacement.IconOnly;
                // Sign the PDF document with another signature.
                sig.Sign(pdfSigner);
                // Save the PDF document.
                document.Save();
            }

            System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo(pdfFile) { UseShellExecute = true });
        }
    }
}

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Option Infer On

Imports System
Imports System.IO
Imports SautinSoft
Imports SautinSoft.Pdf
Imports SautinSoft.Pdf.Annotations
Imports SautinSoft.Pdf.Content
Imports SautinSoft.Pdf.Forms
Imports SautinSoft.Pdf.Security

Namespace Sample
	Friend Class Sample
		''' <summary>
		''' Add multisign in PDF.
		''' </summary>
		''' <remarks>
		''' Details: https://sautinsoft.com/products/pdf/help/net/developer-guide/add-multi-signature.php
		''' </remarks>
		Shared Sub Main(ByVal args() As String)
			' Before starting this example, please get a free 100-day trial key:
			' https://sautinsoft.com/start-for-free/

			' Apply the key here:
			' PdfDocument.SetLicense("...");

			Dim pdfFile As String = Path.GetFullPath("..\..\..\simple text.pdf")

			Dim document = PdfDocument.Load(pdfFile)
			If True Then
				' Add a signature field.
				Dim sig = document.Form.Fields.AddSignature(document.Pages(0), 10, 10, 250, 50)
				' Create new Signer.
				Dim pdfSigner As New PdfSigner("..\..\..\Oliver Ekman.pfx", "1234567890")
				' Configure signer.
				pdfSigner.Timestamper = New PdfTimestamper("https://tsa.cesnet.cz:5817/tsa")
				pdfSigner.SignatureFormat = PdfSignatureFormat.CAdES
				pdfSigner.SignatureLevel = PdfSignatureLevel.PAdES_B_LTA
				pdfSigner.HashAlgorithm = PdfHashAlgorithm.SHA256
				pdfSigner.AuthorPermission = PdfUserAccessPermissions.CommentAndFillForm
				pdfSigner.Location = "Test workplace"
				pdfSigner.Reason = "Test"
				Dim im = PdfImage.Load("..\..\..\JPEG1.jpg")
				sig.Appearance.Icon = im
				sig.Appearance.TextPlacement = PdfTextPlacement.TextRightOfIcon
				' Sign PDF Document.
				sig.Sign(pdfSigner)
				' Save the PDF document. Saving is required to add the next signature. 
				document.Save()
				' Add a new signature field.
				sig = document.Form.Fields.AddSignature(document.Pages(1), 10, 10, 100, 50)
				' Create new Signer.
				pdfSigner = New PdfSigner("..\..\..\sautinsoft.pfx", "123456789")
				' Configure signer.
				pdfSigner.Timestamper = New PdfTimestamper("https://freetsa.org/tsr")
				pdfSigner.SignatureFormat = PdfSignatureFormat.CAdES
				pdfSigner.SignatureLevel = PdfSignatureLevel.PAdES_B_LTA
				pdfSigner.HashAlgorithm = PdfHashAlgorithm.SHA256
				pdfSigner.Location = "Test workplace"
				pdfSigner.Reason = "Test"
				im = PdfImage.Load("..\..\..\JPEG2.jpg")
				sig.Appearance.Icon = im
				sig.Appearance.TextPlacement = PdfTextPlacement.IconOnly
				' Sign the PDF document with another signature.
				sig.Sign(pdfSigner)
				' Save the PDF document.
				document.Save()
			End If

			System.Diagnostics.Process.Start(New System.Diagnostics.ProcessStartInfo(pdfFile) With {.UseShellExecute = True})
		End Sub
	End Class
End Namespace

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Мы разрабатываем компоненты .Net с 2002 года. Мы знаем форматы PDF, DOCX, RTF, HTML, XLSX и Images. Если вам нужна помощь в создании, изменении или преобразовании документов в различных форматах, мы можем вам помочь. Мы напишем для вас любой пример кода абсолютно бесплатно.