Section:

Encryption

Sample C# code for using Apryse SDK to read encrypted (password protected) documents, secure a document with encryption, or remove encryption. Learn more about our Server SDK.

1//
2// Copyright (c) 2001-2024 by Apryse Software Inc. All Rights Reserved.
3//
4
5using System;
6using pdftron;
7using pdftron.Common;
8using pdftron.Filters;
9using pdftron.SDF;
10using pdftron.PDF;
11
12namespace EncTestCS
13{
14	// A custom security handler used to obtain document password dynamically via user feedback. 
15	class MySecurityHandler : StdSecurityHandler
16	{
17		public MySecurityHandler (Int32 key_len, Int32 enc_code) : base(key_len, enc_code) {}
18		public MySecurityHandler (MySecurityHandler s) : base(s) {}
19
20		// In this callback ask the user for password/authorization data. 
21		// This may involve a dialog box used to collect authorization data or something else.
22		override public bool GetAuthorizationData (SecurityHandler.Permission p) 
23		{ 
24			Console.WriteLine("The input file requires user password.");
25			Console.WriteLine("Please enter the password:");
26			String pass = Console.ReadLine();
27			InitPassword(pass);
28			return true; 
29		}
30
31		// This callback could be used to customize security handler preferences.
32		override public bool EditSecurityData(SDFDoc doc) { return false; }
33
34		// This callback is used when authorization process fails. 
35		override public void AuthorizeFailed() 
36		{
37			Console.WriteLine("Authorize failed...");
38		}
39
40		public static SecurityHandler Create(String name, Int32 key_len, Int32 enc_code) { return new MySecurityHandler(key_len, enc_code); }
41
42		override public SecurityHandler Clone() { return new MySecurityHandler(this); }
43	}
44
45	/// <summary>
46	//---------------------------------------------------------------------------------------
47	// This sample shows encryption support in PDFNet. The sample reads an encrypted document and 
48	// sets a new SecurityHandler. The sample also illustrates how password protection can 
49	// be removed from an existing PDF document.
50	//---------------------------------------------------------------------------------------
51	/// </summary>
52	class Class1
53	{
54		private static pdftron.PDFNetLoader pdfNetLoader = pdftron.PDFNetLoader.Instance();
55		static Class1() {}
56		
57		static void Main(string[] args)
58		{
59			PDFNet.Initialize(PDFTronLicense.Key);
60
61			// Relative path to the folder containing test files.
62			string input_path =  "../../../../TestFiles/";
63			string output_path = "../../../../TestFiles/Output/";
64
65			// Example 1: Securing a document with password protection and adjusting permissions 
66			// on the document.
67			try
68			{
69				// Open the test file
70				Console.WriteLine("-------------------------------------------------");
71				Console.WriteLine("Securing an existing document...");
72				using (PDFDoc doc = new PDFDoc(input_path + "fish.pdf"))
73				{
74
75					if (!doc.InitSecurityHandler()) 
76					{
77						Console.WriteLine("Document authentication error...");
78						return;
79					}
80					
81					// Perform some operation on the document. In this case we use low level SDF API
82					// to replace the content stream of the first page with contents of file 'my_stream.txt'
83					if (true)  // Optional
84					{
85						Console.WriteLine("Replacing the content stream, use flate compression...");
86
87						// Get the first page dictionary using the following path: trailer/Root/Pages/Kids/0
88						Obj page_dict = doc.GetTrailer().Get("Root").Value().
89							Get("Pages").Value().Get("Kids").Value().GetAt(0);
90
91						// Embed a custom stream (file mystream.txt) using Flate compression.
92						MappedFile embed_file = new MappedFile(input_path + "my_stream.txt");
93						FilterReader mystm = new FilterReader(embed_file);
94						page_dict.Put("Contents", doc.CreateIndirectStream(mystm));
95						embed_file.Close();
96					}
97				
98					// Apply a new security handler with given security settings. 
99					// In order to open saved PDF you will need a user password 'test'.
100					StdSecurityHandler new_handler = new StdSecurityHandler();
101
102					// Set a new password required to open a document
103					string my_password = "test";				
104					new_handler.ChangeUserPassword(my_password);
105
106					// Set Permissions
107					new_handler.SetPermission (SecurityHandler.Permission.e_print, true);
108					new_handler.SetPermission (SecurityHandler.Permission.e_extract_content, false);
109
110					// Note: document takes the ownership of new_handler.
111					doc.SetSecurityHandler(new_handler);
112
113					// Save the changes.
114					Console.WriteLine("Saving modified file...");
115					doc.Save(output_path + "secured.pdf", 0);
116				}
117
118				Console.WriteLine("Done. Result saved in secured.pdf");
119			}
120			catch (PDFNetException e)
121			{
122				Console.WriteLine(e.Message);
123			}
124
125			// Example 2: Reading password protected document without user feedback.
126			try
127			{
128				// In this sample case we will open an encrypted document that 
129				// requires a user password in order to access the content.
130				Console.WriteLine("-------------------------------------------------");
131				Console.WriteLine("Open the password protected document from the first example...");
132				using (PDFDoc doc = new PDFDoc(output_path + "secured.pdf"))	// Open the encrypted document that we saved in the first example. 
133				{
134
135					Console.WriteLine("Initializing security handler without any user interaction...");
136					
137					// At this point MySecurityHandler callbacks will be invoked. 
138					// MySecurityHandler.GetAuthorizationData() should collect the password and 
139					// AuthorizeFailed() is called if user repeatedly enters a wrong password.
140					if (!doc.InitStdSecurityHandler("test")) 
141					{
142						Console.WriteLine("Document authentication error...");
143						Console.WriteLine("The password is not valid.");
144						return;
145					}
146					else 
147					{
148						Console.WriteLine("The password is correct! Document can now be used for reading and editing");
149
150						// Remove the password security and save the changes to a new file.
151						doc.RemoveSecurity();
152						doc.Save(output_path + "secured_nomore1.pdf", 0);
153						Console.WriteLine("Done. Result saved in secured_nomore1.pdf");
154					}
155
156				}
157			}
158			catch (PDFNetException e)
159			{
160				Console.WriteLine(e.Message);
161			}
162
163			// Example 3:
164			// Encrypt/Decrypt a PDF using PDFTron custom security handler
165			try
166			{
167				Console.WriteLine("-------------------------------------------------");
168				Console.WriteLine("Encrypt a document using PDFTron Custom Security handler with a custom id and password...");
169				PDFDoc doc = new PDFDoc(input_path + "BusinessCardTemplate.pdf");
170
171				// Create PDFTron custom security handler with a custom id. Replace this with your own integer
172				int custom_id = 123456789;
173				PDFTronCustomSecurityHandler custom_handler = new PDFTronCustomSecurityHandler(custom_id);
174
175				// Add a password to the custom security handler
176				String pass = "test";
177				custom_handler.ChangeUserPassword(pass);
178
179				// Save the encrypted document
180				doc.SetSecurityHandler(custom_handler);
181				doc.Save(output_path + "BusinessCardTemplate_enc.pdf", 0);
182
183				Console.WriteLine("Decrypt the PDFTron custom security encrypted document above...");
184				// Register the PDFTron Custom Security handler with the same custom id used in encryption
185				PDFNet.AddPDFTronCustomHandler(custom_id);
186
187				PDFDoc doc_enc = new PDFDoc(output_path + "BusinessCardTemplate_enc.pdf");
188				doc_enc.InitStdSecurityHandler(pass);
189				doc_enc.RemoveSecurity();
190				// Save the decrypted document
191				doc_enc.Save(output_path + "BusinessCardTemplate_enc_dec.pdf", 0);
192				Console.WriteLine("Done. Result saved in BusinessCardTemplate_enc_dec.pdf");
193			}
194			catch (PDFNetException e)
195			{
196				Console.WriteLine(e.Message);
197			}
198
199			// Example 4: Reading password protected document with user feedback.
200			try
201			{
202				// Register standard security. Reguired only once per application session.
203				CreateDelegate del = new CreateDelegate(MySecurityHandler.Create);
204				SecurityManagerSingleton.Instance().RegisterSecurityHandler("Standard", 
205					new SecurityDescriptor("Standard Security", del));
206
207				Console.WriteLine("-------------------------------------------------");
208				Console.WriteLine("Open the password protected document from the first example...");
209				using (PDFDoc doc = new PDFDoc(output_path + "secured.pdf")) // Open the encrypted document that we saved in the first example. 
210				{
211
212					Console.WriteLine("Initializing security handler. The password will now be collected from the user");
213					Console.WriteLine("Enter 'test' as the password.");
214
215					// At this point MySecurityHandler callbacks will be invoked. 
216					// MySecurityHandler.GetAuthorizationData() should collect the password and 
217					// AuthorizeFailed() is called if user repeatedly enters a wrong password.
218					if (!doc.InitSecurityHandler()) 
219					{
220						Console.WriteLine("Document authentication error...");
221						Console.WriteLine("The password is not valid.");
222						return;
223					}
224					else 
225					{
226						Console.WriteLine("The password is correct! Document can now be used for reading and editing");
227
228						// Remove the password security and save the changes to a new file.
229						doc.RemoveSecurity();
230						doc.Save(output_path + "secured_nomore2.pdf", 0);
231						Console.WriteLine("Done. Result saved in secured_nomore2.pdf");
232					}
233				}
234			}
235			catch (PDFNetException e)
236			{
237				Console.WriteLine(e.Message);
238			}
239			PDFNet.Terminate();
240			Console.WriteLine("-------------------------------------------------");
241			Console.WriteLine("Tests completed.");
242
243		}
244	}
245}

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