// // This code is part of Document Solutions for PDF demos. // Copyright (c) MESCIUS inc. All rights reserved. // using System; using System.IO; using System.Drawing; using GrapeCity.Documents.Pdf; using GrapeCity.Documents.Text; using GrapeCity.Documents.Pdf.Security; namespace DsPdfWeb.Demos { // This sample demonstrates the use of Security.EncryptHandler and Security.DecryptHandler. // Security.DecryptHandler allows you to examine the security attributes of an existing PDF. // Security.EncryptHandler allows you to specify security attributes when saving a PDF. // DsPdf supports Standard Security Handlers revisions 2, 3, 4, 5 and 6 as defined // in the PDF Spec 1.7 and 2.0. In this sample, we use StandardSecurityHandlerRev4. // // See SecurityHandlerRev6 for a Standard Security Handler revision 6 demo. public class SecurityHandlers { public int CreatePDF(Stream stream) { // Sample passwords: const string ownerPassword = "I'm the owner"; const string userPassword = "I'm a user"; // Step 1: Generate a document with some security attributes: var doc0 = new GcPdfDocument(); var rc0 = Common.Util.AddNote( "Demonstrating security:\n" + "In this PDF, we specify certain encryption options,\n" + "and set owner and user passwords.", doc0.NewPage()); // Create a Rev4 security handler: var ssh4 = new StandardSecurityHandlerRev4() { // Set some rev4 specific props: EncryptionAlgorithm = EncryptionAlgorithm.AES, EncryptStrings = true, }; // StandardSecurityHandlerRev4 is derived from StandardSecurityHandlerRev3, // so we can do this to make sure we touch rev3-specific properties only // (the cast is for illustration only, you do not need it to set those props of course): if (ssh4 is StandardSecurityHandlerRev3 ssh3) { ssh3.EditingPermissions = EditingPermissions.AssembleDocument; ssh3.PrintingPermissions = PrintingPermissions.LowResolution; } // But StandardSecurityHandlerRev3 is NOT derived from StandardSecurityHandlerRev2, // because some properties have similar meanings but different syntax, so this: // if (ssh3 is StandardSecurityHandlerRev2 ssh2) { ... } // will NOT work. // Set some passwords: ssh4.OwnerPassword = ownerPassword; ssh4.UserPassword = userPassword; // Assign the handler we created to the document so that it is used when saving the PDF: doc0.Security.EncryptHandler = ssh4; // Save the PDF in a temp file, so that we can load it: var fn = Path.GetTempFileName(); doc0.Save(fn); // Step 2: Load the generated PDf and examine its security attributes: var doc = new GcPdfDocument(); using (var fs = File.OpenRead(fn)) { // User password is needed to load the document: doc.Load(fs, userPassword); // At this point we can examine doc.Security.DecryptHandler if it exists, // but there is NO Security.EncryptHandler: if (doc.Security.EncryptHandler != null) throw new Exception("This should not happen."); var dh = doc.Security.DecryptHandler; if (dh is StandardSecurityHandlerRev4 dh_ssh4) { // Make sure the loaded permissions are what we specified in Step 1: Common.Util.AddNote( string.Format("Security attributes that were in the loaded PDF's DecryptHandler:\n" + "EditingPermissions: {0}\n" + "PrintingPermissions: {1}", dh_ssh4.EditingPermissions, dh_ssh4.PrintingPermissions), doc.Pages[0], new RectangleF(72, rc0.Bottom + 36, 72 * 6, 72 * 2)); // This won't work, sorry: var noway = dh_ssh4.OwnerPassword; if (noway != null) throw new Exception("No way."); } else if (dh is StandardSecurityHandlerRev3 dh_ssh3) { // If we didn't know that we have a Rev4 handler, we would add code here, } else if (dh is StandardSecurityHandlerRev2 dh_ssh2) { // ... and here, } else { // ... and done something in this case too. } // Save the new PDF - but PLEASE NOTE that because we did not set // the Security.EncryptHandler, the newly saved document has no security! doc.Save(stream); } // Clean up the temp file: File.Delete(fn); // Done: return doc.Pages.Count; } } }