957004_ex Added Added validate and classify digital signatures in a PDF sample

Digital Signature/Validate-and-classify-digital-signatures/.NET/Validate-and-classify-digital-signatures.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.12.35707.178 d17.12
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Validate-and-classify-digital-signatures", "Validate-and-classify-digital-signatures\Validate-and-classify-digital-signatures.csproj", "{7048D610-0768-4A32-BB1E-B6840910C698}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{7048D610-0768-4A32-BB1E-B6840910C698}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{7048D610-0768-4A32-BB1E-B6840910C698}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{7048D610-0768-4A32-BB1E-B6840910C698}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{7048D610-0768-4A32-BB1E-B6840910C698}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+EndGlobal

Digital Signature/Validate-and-classify-digital-signatures/.NET/Validate-and-classify-digital-signatures/Program.cs

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+using Syncfusion.Pdf.Parsing;
+using Syncfusion.Pdf.Security;
+
+//Get the stream from the document
+using (FileStream documentStream = new FileStream(Path.GetFullPath(@"Data/Input.pdf"), FileMode.Open, FileAccess.Read))
+{
+    // Load the signed PDF document
+    PdfLoadedDocument loadedDocument = new PdfLoadedDocument(documentStream);
+
+    // Get the PDF form
+    PdfLoadedForm form = loadedDocument.Form;
+
+    // Initialize flag to detect timestamp signatures
+    bool isTimeStampSignature = false;
+
+    // Loop through all form fields in reverse
+    for (int i = form.Fields.Count - 1; i >= 0; i--)
+    {
+        PdfLoadedField field = form.Fields[i] as PdfLoadedField;
+
+        // Check if the field is a signature field
+        if (field is PdfLoadedSignatureField)
+        {
+            PdfLoadedSignatureField signatureField = field as PdfLoadedSignatureField;
+            Console.WriteLine("Signature field name: " + signatureField.Name);
+
+            // Validate the signature
+            PdfSignatureValidationResult result = signatureField.ValidateSignature();
+
+            if (result != null)
+            {
+                // Check if it's a timestamp signature
+                if (result.TimeStampInformation != null && result.TimeStampInformation.IsDocumentTimeStamp)
+                {
+                    isTimeStampSignature = true;
+                    Console.WriteLine("Signature is a time stamp signature.");
+                }
+                else
+                {
+                    bool isCAdES = false;
+
+                    // Check if the cryptographic standard is CAdES
+                    if (result.CryptographicStandard == CryptographicStandard.CADES)
+                    {
+                        isCAdES = true;
+                    }
+
+                    // Check if LTV (Long-Term Validation) is enabled
+                    if (result.LtvVerificationInfo.IsLtvEnabled)
+                    {
+                        // Identify the type of long-term signature
+                        if (isCAdES && isTimeStampSignature)
+                        {
+                            Console.WriteLine("LTA signature.");
+                        }
+                        else
+                        {
+                            Console.WriteLine("LTV signature.");
+                        }
+                    }
+                    else
+                    {
+                        Console.WriteLine("No LTV signature.");
+                    }
+                }
+            }
+            else
+            {
+                Console.WriteLine("Signature is not valid.");
+            }
+        }
+    }
+    // Close the PDF document.
+    loadedDocument.Close(true);
+}

Digital Signature/Validate-and-classify-digital-signatures/.NET/Validate-and-classify-digital-signatures/Validate-and-classify-digital-signatures.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <RootNamespace>Validate_and_classify_digital_signatures</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Syncfusion.Pdf.Net.Core" Version="*" />
+  </ItemGroup>
+
+</Project>