C# Requires Chilkat v11.7.0+

Encrypt a PDF for a Certificate Instead of a Password

See more PDF Protection Examples

Demonstrates certificate security, where a PDF is encrypted for one or more recipients and each opens it with their own certificate and private key. No password is involved. Only the public certificate of a recipient is needed to encrypt. Each recipient has its own permissions, and the changeSecurity permission gives a recipient owner rights. PreLoadCheck tells an application that a file is certificate-encrypted and which certificates can open it. A PDF that cannot be opened, because no matching certificate and private key were provided, fails to load. 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

//  The recipient's certificate.  Only the public certificate is needed to encrypt.
Chilkat.Cert recipient = new Chilkat.Cert();
success = recipient.LoadFromFile("qa_data/certs/recipient.cer");
if (success == false) {
    Debug.WriteLine(recipient.LastErrorText);
    return;
}

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

//  Call AddEncryptCert once for each recipient.
success = pdf.AddEncryptCert(recipient);
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

//  recipientPermissions[0] belongs to the first certificate added.  changeSecurity gives that
//  recipient owner rights, so the file can be managed later.
Chilkat.JsonObject json = new Chilkat.JsonObject();
json.UpdateString("method","certificate");
json.UpdateBool("recipientPermissions[0].changeSecurity",true);

Chilkat.JsonObject jsonOut = new Chilkat.JsonObject();
success = pdf.Protection("encrypt",json,jsonOut);
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

Debug.WriteLine("method: " + jsonOut.StringOf("pending.method"));
Debug.WriteLine("algorithm: " + jsonOut.StringOf("pending.algorithm"));
Debug.WriteLine("recipients: " + Convert.ToString(jsonOut.SizeOfArray("pending.recipients")));

success = pdf.WriteFile("qa_output/memo_for_recipient.pdf");
if (success == false) {
    Debug.WriteLine(pdf.LastErrorText);
    return;
}

//  PreLoadCheck says how the file is protected, without loading it.
Chilkat.Pdf reader = new Chilkat.Pdf();
Chilkat.JsonObject info = new Chilkat.JsonObject();
success = reader.PreLoadCheck("qa_output/memo_for_recipient.pdf",info);
if (success == false) {
    Debug.WriteLine(reader.LastErrorText);
    return;
}

Debug.WriteLine("saved file, method: " + info.StringOf("method"));
Debug.WriteLine("saved file, recipients: " + Convert.ToString(info.SizeOfArray("recipients")));

//  The recipient opens it with the certificate and its private key, here from a .pfx file.
//  (On Windows, a certificate that is installed in the Windows certificate store with its private
//  key is found automatically when the PDF is loaded, and SetDecryptCert is not needed for it.)
Chilkat.Cert myCert = new Chilkat.Cert();
success = myCert.LoadPfxFile("qa_data/pfx/recipient.pfx","pfx-password");
if (success == false) {
    Debug.WriteLine(myCert.LastErrorText);
    return;
}

success = reader.SetDecryptCert(myCert);
if (success == false) {
    Debug.WriteLine(reader.LastErrorText);
    return;
}

success = reader.LoadFile("qa_output/memo_for_recipient.pdf");
if (success == false) {
    Debug.WriteLine(reader.LastErrorText);
    return;
}

Chilkat.JsonObject empty = new Chilkat.JsonObject();
Chilkat.JsonObject loadedInfo = new Chilkat.JsonObject();
success = reader.Protection("getInfo",empty,loadedInfo);
if (success == false) {
    Debug.WriteLine(reader.LastErrorText);
    return;
}

Debug.WriteLine("opened with: " + loadedInfo.StringOf("loaded.openedWith"));
Debug.WriteLine("pages: " + Convert.ToString(reader.NumPages));

//  Sample output:

//  method: certificate
//  algorithm: aes-256
//  recipients: 1
//  saved file, method: certificate
//  saved file, recipients: 1
//  opened with: certificate
//  pages: 2