.NET Core C# Requires Chilkat v11.7.0+

Password-Protect a PDF with AES-256 Encryption

See more PDF Protection Examples

Demonstrates the simplest way to encrypt a PDF so that it needs a password to open. The passwords come from the UserPassword and OwnerPassword properties, and Protection with the encrypt operation and an empty JSON uses the defaults: AES-256, everything encrypted, every permission granted. Protection only records the security the PDF will be saved with. Nothing is encrypted until WriteFile is called. .NET Core C#

bool success = false;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  The PDF used in this example is available at two_page_memo.pdf

Chilkat.Pdf pdf = new Chilkat.Pdf();
success = pdf.LoadFile("qa_data/pdf/two_page_memo.pdf");
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

//  The passwords are taken from these two properties at the time Protection is called.
//  The user password opens the PDF.  The owner password opens it too, and is the one needed
//  later to change or remove the protection.
pdf.UserPassword = "user-secret";
pdf.OwnerPassword = "owner-secret";

//  An empty JSON asks for the defaults: AES-256, everything encrypted, every permission granted.
Chilkat.JsonObject json = new Chilkat.JsonObject();
Chilkat.JsonObject jsonOut = new Chilkat.JsonObject();
success = pdf.Protection("encrypt",json,jsonOut);
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

//  Nothing has been encrypted yet.  "pending" describes the security the PDF will be saved with.
Debug.WriteLine("algorithm: " + jsonOut.StringOf("pending.algorithm"));
Debug.WriteLine("PDF version: " + jsonOut.StringOf("pending.pdfVersion"));
Debug.WriteLine("password needed to open: " + Convert.ToString(jsonOut.BoolOf("pending.userPasswordRequired")));

//  Writing the file applies it.
success = pdf.WriteFile("qa_output/memo_encrypted.pdf");
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

//  PreLoadCheck reports a file's encryption without loading it, and needs no password.
Chilkat.Pdf checker = new Chilkat.Pdf();
Chilkat.JsonObject info = new Chilkat.JsonObject();
success = checker.PreLoadCheck("qa_output/memo_encrypted.pdf",info);
if (success == false) {
    Debug.WriteLine(checker.LastErrorText);
    return;
}

Debug.WriteLine("encrypted: " + Convert.ToString(info.BoolOf("encrypted")));
Debug.WriteLine("openPasswordRequired: " + Convert.ToString(info.BoolOf("openPasswordRequired")));

//  With the password, the PDF opens normally.
Chilkat.Pdf reader = new Chilkat.Pdf();
reader.UserPassword = "user-secret";
success = reader.LoadFile("qa_output/memo_encrypted.pdf");
if (success == false) {
    Debug.WriteLine(reader.LastErrorText);
    return;
}

Debug.WriteLine("pages: " + Convert.ToString(reader.NumPages));

//  Sample output:

//  algorithm: aes-256
//  PDF version: 1.7
//  password needed to open: True
//  encrypted: True
//  openPasswordRequired: True
//  pages: 2