259676: Added more information about the time stamp in the UG documentation link

Author: sameerkhan001

Digital Signature/Validate-the-digitally-signed-PDF-signature/.NET/Validate-the-digitally-signed-PDF-signature/Program.cs

@@ -4,60 +4,77 @@
 using Syncfusion.Pdf.Security;
 using System.Security.Cryptography.X509Certificates;
 
-//Get the stream from the document.
-FileStream documentStream = new FileStream(Path.GetFullPath(@"Data/Input.pdf"), FileMode.Open, FileAccess.Read);
+// Load the input PDF document stream from the specified file path
+using (FileStream documentStream = new FileStream(Path.GetFullPath(@"Data/Input.pdf"), FileMode.Open, FileAccess.Read))
+{
 
-//Load an existing signed PDF document.
-PdfLoadedDocument loadedDocument = new PdfLoadedDocument(documentStream);
+    // Load the signed PDF document using the stream
+    using (PdfLoadedDocument loadedDocument = new PdfLoadedDocument(documentStream))
+    {
 
-//Get signature field.
-PdfLoadedSignatureField signatureField = loadedDocument.Form.Fields[0] as PdfLoadedSignatureField;
+        // Retrieve the first signature field from the PDF form
+        PdfLoadedSignatureField signatureField = loadedDocument.Form.Fields[0] as PdfLoadedSignatureField;
 
-//X509Certificate2Collection to check the signer's identity using root certificates.
-X509CertificateCollection collection = new X509CertificateCollection();
+        // Create a certificate collection to hold trusted root certificates for validation
+        X509CertificateCollection collection = new X509CertificateCollection();
 
-//Creates a certificate instance from PFX file with private key.
-FileStream certificateStream = new FileStream(Path.GetFullPath(@"Data/PDF.pfx"), FileMode.Open, FileAccess.Read);
-byte[] data = new byte[certificateStream.Length];
-certificateStream.Read(data, 0, data.Length);
+        // Load the root certificate from a PFX file (includes private key)
+        FileStream certificateStream = new FileStream(Path.GetFullPath(@"Data/PDF.pfx"), FileMode.Open, FileAccess.Read);
+        byte[] data = new byte[certificateStream.Length];
+        certificateStream.Read(data, 0, data.Length);
 
-//Create new X509Certificate2 with the root certificate.
-X509Certificate2 certificate = new X509Certificate2(data, "syncfusion");
+        // Create an X509Certificate2 instance using the loaded certificate data and password
+        X509Certificate2 certificate = new X509Certificate2(data, "syncfusion");
 
-//Add the certificate to the collection.
-collection.Add(certificate);
+        // Add the certificate to the validation collection
+        collection.Add(certificate);
 
-//Validate signature and get the validation result.
-PdfSignatureValidationResult result = signatureField.ValidateSignature(collection);
+        // Validate the signature using the provided certificate collection
+        PdfSignatureValidationResult result = signatureField.ValidateSignature(collection);
 
-//Checks whether the signature is valid or not.
-SignatureStatus status = result.SignatureStatus;
+        // Check if the signature is valid
+        SignatureStatus status = result.SignatureStatus;
 
-//Checks whether the document is modified or not.
-bool isModified = result.IsDocumentModified;
+        // Check if the document has been modified after signing
+        bool isModified = result.IsDocumentModified;
 
-Console.WriteLine("Document modified: " + isModified);
+        // Check if Long-Term Validation (LTV) is enabled in the signature
+        bool isLtvEnabled = result.LtvVerificationInfo.IsLtvEnabled;
 
-//Signature details.
-string issuerName = signatureField.Signature.Certificate.IssuerName;
-DateTime validFrom = signatureField.Signature.Certificate.ValidFrom;
-DateTime validTo = signatureField.Signature.Certificate.ValidTo;
-string signatureAlgorithm = result.SignatureAlgorithm;
-DigestAlgorithm digestAlgorithm = result.DigestAlgorithm;
+        // Check if Certificate Revocation List (CRL) data is embedded in the PDF
+        bool isCrlEmbedded = result.LtvVerificationInfo.IsCrlEmbedded;
 
-Console.WriteLine("Issuer Name: " + issuerName);
-Console.WriteLine("Valid From: " + validFrom);
-Console.WriteLine("Valid To: " + validTo);
-Console.WriteLine("Signature Algorithm: " + signatureAlgorithm);
-Console.WriteLine("Digest Algorithm: " + digestAlgorithm);
+        // Check if Online Certificate Status Protocol (OCSP) data is embedded in the PDF
+        bool isOcspEmbedded = result.LtvVerificationInfo.IsOcspEmbedded;
 
-//Revocation validation details.
-RevocationResult revocationDetails = result.RevocationResult;
-RevocationStatus revocationStatus = revocationDetails.OcspRevocationStatus;
-bool isRevokedCRL = revocationDetails.IsRevokedCRL;
+        // Output the validation results to the console
+        Console.WriteLine("Document modified: " + isModified);
+        Console.WriteLine("LTV enabled: " + isLtvEnabled);
+        Console.WriteLine("CRL embedded: " + isCrlEmbedded);
+        Console.WriteLine("OCSP embedded: " + isOcspEmbedded);
 
-Console.WriteLine("Revocation Status: " + revocationStatus);
-Console.WriteLine("Is Revoked CRL: " + isRevokedCRL);
+        // Extract and display signature certificate details
+        string issuerName = signatureField.Signature.Certificate.IssuerName;
+        DateTime validFrom = signatureField.Signature.Certificate.ValidFrom;
+        DateTime validTo = signatureField.Signature.Certificate.ValidTo;
+        string signatureAlgorithm = result.SignatureAlgorithm;
+        DigestAlgorithm digestAlgorithm = result.DigestAlgorithm;
 
-//Close the document.
-loadedDocument.Close(true);
+        Console.WriteLine("Issuer Name: " + issuerName);
+        Console.WriteLine("Valid From: " + validFrom);
+        Console.WriteLine("Valid To: " + validTo);
+        Console.WriteLine("Signature Algorithm: " + signatureAlgorithm);
+        Console.WriteLine("Digest Algorithm: " + digestAlgorithm);
+
+        // Extract and display revocation validation details
+        RevocationResult revocationDetails = result.RevocationResult;
+        RevocationStatus revocationStatus = revocationDetails.OcspRevocationStatus;
+        bool isRevokedCRL = revocationDetails.IsRevokedCRL;
+
+        Console.WriteLine("Revocation Status: " + revocationStatus);
+        Console.WriteLine("Is Revoked CRL: " + isRevokedCRL);
+
+        // Close the loaded PDF document and release resources
+        loadedDocument.Close(true);
+    }
+}