Task-935629-How to digitally sign all pages in the PDF document using C#

Digital Signature/How-to-apply-multiple-signatures-to-a-PDF-in-C#/How-to-apply-multiple-signatures-to-a-PDF-in-C#.slnx

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+<Solution>
+  <Project Path="How-to-apply-multiple-signatures-to-a-PDF-in-C#/How-to-apply-multiple-signatures-to-a-PDF-in-C#.csproj" />
+</Solution>

Digital Signature/How-to-apply-multiple-signatures-to-a-PDF-in-C#/How-to-apply-multiple-signatures-to-a-PDF-in-C#/How-to-apply-multiple-signatures-to-a-PDF-in-C#.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <RootNamespace>How_to_apply_multiple_signatures_to_a_PDF_in_C_</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <None Remove="Data\Input.pdf" />
+    <None Remove="Data\PDF.pfx" />
+    <None Remove="Data\SignatureFields.pdf" />
+    <None Remove="Data\Student Signature.jpg" />
+    <None Remove="Data\Teacher Signature.png" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <EmbeddedResource Include="Data\Input.pdf">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </EmbeddedResource>
+    <EmbeddedResource Include="Data\PDF.pfx">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </EmbeddedResource>
+    <EmbeddedResource Include="Data\SignatureFields.pdf">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </EmbeddedResource>
+    <EmbeddedResource Include="Data\Student Signature.jpg">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </EmbeddedResource>
+    <EmbeddedResource Include="Data\Teacher Signature.png">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </EmbeddedResource>
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Syncfusion.Pdf.Net.Core" Version="*" />
+  </ItemGroup>
+
+</Project>

Digital Signature/How-to-apply-multiple-signatures-to-a-PDF-in-C#/How-to-apply-multiple-signatures-to-a-PDF-in-C#/Program.cs

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+using Syncfusion.Pdf;
+using Syncfusion.Pdf.Graphics;
+using Syncfusion.Pdf.Parsing;
+using Syncfusion.Pdf.Security;
+
+namespace Create_PDF
+{
+    class Program
+    {
+        public static void Main(string[] args)
+        {
+            //Register your Syncfusion License Key.
+            Syncfusion.Licensing.SyncfusionLicenseProvider.RegisterLicense("Your License Key");
+            //Load the PDF and call the SignPDF method.
+            FileStream fileStream = new FileStream("Data/Input.pdf", FileMode.Open, FileAccess.ReadWrite);
+            MemoryStream outputStream = SignPDF(fileStream, "signature1", 0);
+            //Call the SignPDF method again for second signer
+            MemoryStream outputStream1 = SignPDF(outputStream, "signature2", 1);
+            //Save the final multi signed PDF document
+            File.WriteAllBytes(@"SignedDocument.pdf", outputStream1.ToArray());
+        }
+
+        public static MemoryStream SignPDF(Stream inputStream, string signatureName, int pageIndex)
+        {
+            // Load the PDF document from the input stream
+            PdfLoadedDocument loadedDocument = new PdfLoadedDocument(inputStream);
+
+            // Get the specified page
+            PdfLoadedPage page = loadedDocument.Pages[pageIndex] as PdfLoadedPage;
+
+            // Load the certificate
+            FileStream certificateStream = new FileStream(Path.GetFullPath(@"Data/PDF.pfx"), FileMode.Open, FileAccess.Read);
+            PdfCertificate certificate = new PdfCertificate(certificateStream, "syncfusion");
+
+            // Create the signature
+            PdfSignature signature = new PdfSignature(loadedDocument, page, certificate, signatureName);
+            signature.Bounds = new Syncfusion.Drawing.RectangleF(400, 740, 90, 20);
+
+            // Choose the image based on the signature name
+            string imagePath = signatureName == "signature1"
+                ? @"Data/Student Signature.jpg"
+                : @"Data/Teacher Signature.png";
+
+            FileStream imageStream = new FileStream(Path.GetFullPath(imagePath), FileMode.Open, FileAccess.Read);
+            PdfBitmap signatureImage = new PdfBitmap(imageStream);
+
+            // Draw the image in the signature appearance
+            signature.Appearance.Normal.Graphics.DrawImage(signatureImage, 0, 0, 90, 20);
+
+            // Save the signed document to a memory stream
+            MemoryStream outputStream = new MemoryStream();
+            loadedDocument.Save(outputStream);
+            loadedDocument.Close(true);
+            outputStream.Position = 0; // Reset stream position for next use
+            return outputStream;
+        }
+
+    }
+}