Objective-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. Objective-C

#import <CkoPdf.h>
#import <CkoJsonObject.h>

BOOL success = NO;

//  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

CkoPdf *pdf = [[CkoPdf alloc] init];
success = [pdf LoadFile: @"qa_data/pdf/two_page_memo.pdf"];
if (success == NO) {
    NSLog(@"%@",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.
CkoJsonObject *json = [[CkoJsonObject alloc] init];
CkoJsonObject *jsonOut = [[CkoJsonObject alloc] init];
success = [pdf Protection: @"encrypt" jsonIn: json jsonOut: jsonOut];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

//  Nothing has been encrypted yet.  "pending" describes the security the PDF will be saved with.
NSLog(@"%@%@",@"algorithm: ",[jsonOut StringOf: @"pending.algorithm"]);
NSLog(@"%@%@",@"PDF version: ",[jsonOut StringOf: @"pending.pdfVersion"]);
NSLog(@"%@%d",@"password needed to open: ",[jsonOut BoolOf: @"pending.userPasswordRequired"]);

//  Writing the file applies it.
success = [pdf WriteFile: @"qa_output/memo_encrypted.pdf"];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

//  PreLoadCheck reports a file's encryption without loading it, and needs no password.
CkoPdf *checker = [[CkoPdf alloc] init];
CkoJsonObject *info = [[CkoJsonObject alloc] init];
success = [checker PreLoadCheck: @"qa_output/memo_encrypted.pdf" jsonOut: info];
if (success == NO) {
    NSLog(@"%@",checker.LastErrorText);
    return;
}

NSLog(@"%@%d",@"encrypted: ",[info BoolOf: @"encrypted"]);
NSLog(@"%@%d",@"openPasswordRequired: ",[info BoolOf: @"openPasswordRequired"]);

//  With the password, the PDF opens normally.
CkoPdf *reader = [[CkoPdf alloc] init];
reader.UserPassword = @"user-secret";
success = [reader LoadFile: @"qa_output/memo_encrypted.pdf"];
if (success == NO) {
    NSLog(@"%@",reader.LastErrorText);
    return;
}

NSLog(@"%@%d",@"pages: ",[reader.NumPages intValue]);

//  Sample output:

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