Encryption

1//
2// Copyright (c) 2001-2021 by PDFTron Systems Inc. All Rights Reserved.
3//
4
5using System;
6using pdftron;
7using pdftron.Common;
8using pdftron.Filters;
9using pdftron.SDF;
10using pdftron.PDF;
11
12using NUnit.Framework;
13
14namespace MiscellaneousSamples
15{
16	// A custom security handler used to obtain document password dynamically via user feedback. 
17	/// <summary>
18	//---------------------------------------------------------------------------------------
19	// This sample shows encryption support in PDFNet. The sample reads an encrypted document and 
20	// sets a new SecurityHandler. The sample also illustrates how password protection can 
21	// be removed from an existing PDF document.
22	//---------------------------------------------------------------------------------------
23	/// </summary>
24	[TestFixture]
25	public class EncTest
26	{
27		
28		[Test]
29		public static void Sample()
30		{
31
32			// Relative path to the folder containing test files.
33			const string input_path =  "TestFiles/";
34
35			// Example 1: Securing a document with password protection and adjusting permissions 
36			// on the document.
37			try
38			{
39				// Open the test file
40				Console.WriteLine("-------------------------------------------------");
41				Console.WriteLine("Securing an existing document...");
42				using (PDFDoc doc = new PDFDoc(Utils.GetAssetTempFile(input_path + "fish.pdf")))
43				{
44
45					if (!doc.InitSecurityHandler()) 
46					{
47						Console.WriteLine("Document authentication error...");
48						return;
49					}
50					
51					// Perform some operation on the document. In this case we use low level SDF API
52					// to replace the content stream of the first page with contents of file 'my_stream.txt'
53					if (true)  // Optional
54					{
55						Console.WriteLine("Replacing the content stream, use flate compression...");
56
57						// Get the first page dictionary using the following path: trailer/Root/Pages/Kids/0
58						Obj page_dict = doc.GetTrailer().Get("Root").Value().
59							Get("Pages").Value().Get("Kids").Value().GetAt(0);
60
61						// Embed a custom stream (file mystream.txt) using Flate compression.
62						MappedFile embed_file = new MappedFile(Utils.GetAssetTempFile(input_path + "my_stream.txt"));
63						FilterReader mystm = new FilterReader(embed_file);
64						page_dict.Put("Contents", doc.CreateIndirectStream(mystm));
65						embed_file.Close();
66					}
67				
68					// Apply a new security handler with given security settings. 
69					// In order to open saved PDF you will need a user password 'test'.
70					SecurityHandler new_handler = new SecurityHandler();
71					// Set a new password required to open a document
72					string my_password = "test";				
73					new_handler.ChangeUserPassword(my_password);
74
75					// Set Permissions
76					new_handler.SetPermission (SecurityHandler.Permission.e_print, true);
77					new_handler.SetPermission (SecurityHandler.Permission.e_extract_content, false);
78
79					// Note: document takes the ownership of new_handler.
80					doc.SetSecurityHandler(new_handler);
81
82					// Save the changes.
83					Console.WriteLine("Saving modified file...");
84					doc.Save(Utils.CreateExternalFile("secured.pdf"), 0);
85				}
86
87				Console.WriteLine("Done. Result saved in secured.pdf");
88			}
89			catch (PDFNetException e)
90			{
91				Console.WriteLine(e.Message);
92				Assert.True(false);
93			}
94
95			// Example 2: Reading password protected document without user feedback.
96			try
97			{
98				// In this sample case we will open an encrypted document that 
99				// requires a user password in order to access the content.
100				Console.WriteLine("-------------------------------------------------");
101				Console.WriteLine("Open the password protected document from the first example...");
102				using (PDFDoc doc = new PDFDoc(Utils.CreateExternalFile("secured.pdf")))	// Open the encrypted document that we saved in the first example. 
103				{
104
105					Console.WriteLine("Initializing security handler without any user interaction...");
106					
107					// At this point MySecurityHandler callbacks will be invoked. 
108					// MySecurityHandler.GetAuthorizationData() should collect the password and 
109					// AuthorizeFailed() is called if user repeatedly enters a wrong password.
110					if (!doc.InitStdSecurityHandler("test")) 
111					{
112						Console.WriteLine("Document authentication error...");
113						Console.WriteLine("The password is not valid.");
114						return;
115					}
116					else 
117					{
118						Console.WriteLine("The password is correct! Document can now be used for reading and editing");
119
120						// Remove the password security and save the changes to a new file.
121                        doc.RemoveSecurity();
122						doc.Save(Utils.CreateExternalFile("secured_nomore1.pdf"), 0);
123						Console.WriteLine("Done. Result saved in secured_nomore1.pdf");
124					}
125
126				}
127			}
128			catch (PDFNetException e)
129			{
130				Console.WriteLine(e.Message);
131				Assert.True(false);
132			}
133			
134			Console.WriteLine("Tests completed.");
135
136		}
137	}
138}