Objective-C Requires Chilkat v11.7.0+

Change the Passwords of an Encrypted PDF

See more PDF Protection Examples

Demonstrates the changePasswords operation, which gives an encrypted PDF new user and owner passwords and keeps its algorithm and permissions. The PDF is loaded with its current passwords, the two properties are then set to the new ones, and Protection reads them at the time of the call. Both passwords are replaced, so set both: a property left empty becomes an empty password. 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 encrypted_user_password.pdf

CkoPdf *pdf = [[CkoPdf alloc] init];

//  Load with the current passwords.
pdf.UserPassword = @"secret";
pdf.OwnerPassword = @"owner-secret";
success = [pdf LoadFile: @"qa_data/pdf/encrypted_user_password.pdf"];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

//  The new passwords.  Protection reads the properties as they are when it is called.
pdf.UserPassword = @"new-user-secret";
pdf.OwnerPassword = @"new-owner-secret";

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

//  The algorithm and the permissions are kept.
NSLog(@"%@%@",@"algorithm: ",[jsonOut StringOf: @"pending.algorithm"]);
NSLog(@"%@%d",@"password needed to open: ",[jsonOut BoolOf: @"pending.userPasswordRequired"]);

success = [pdf WriteFile: @"qa_output/minutes_new_passwords.pdf"];
if (success == NO) {
    NSLog(@"%@",pdf.LastErrorText);
    return;
}

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

success = [reader Protection: @"getInfo" jsonIn: json jsonOut: jsonOut];
if (success == NO) {
    NSLog(@"%@",reader.LastErrorText);
    return;
}

NSLog(@"%@%@",@"with the new user password, opened with: ",[jsonOut StringOf: @"loaded.openedWith"]);

//  And so does the new owner password.
CkoPdf *owner = [[CkoPdf alloc] init];
owner.OwnerPassword = @"new-owner-secret";
success = [owner LoadFile: @"qa_output/minutes_new_passwords.pdf"];
if (success == NO) {
    NSLog(@"%@",owner.LastErrorText);
    return;
}

success = [owner Protection: @"getInfo" jsonIn: json jsonOut: jsonOut];
if (success == NO) {
    NSLog(@"%@",owner.LastErrorText);
    return;
}

NSLog(@"%@%@",@"with the new owner password, opened with: ",[jsonOut StringOf: @"loaded.openedWith"]);

//  Sample output:

//  algorithm: rc4-128
//  password needed to open: True
//  with the new user password, opened with: user
//  with the new owner password, opened with: owner