Android™ Requires Chilkat v11.7.0+

Encrypt and Sign a PDF, and Sign an Encrypted PDF

See more PDF Protection Examples

Demonstrates signing together with encryption. A pending encrypt is applied by SignPdf before it signs, so one call produces a PDF that is both encrypted and signed. A PDF that is already encrypted can be signed too, and stays encrypted. When it was opened with only the user password its permissions decide: adding a signature field needs both the modify and the annotate permission. Loading the PDF with its owner password lifts that. Android™

// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    boolean 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 signing certificate, with its private key.
    CkCert cert = new CkCert();
    success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret");
    if (success == false) {
        Log.i(TAG, cert.lastErrorText());
        return;
        }

    CkPdf pdf = new CkPdf();
    success = pdf.LoadFile("qa_data/pdf/two_page_memo.pdf");
    if (success == false) {
        Log.i(TAG, pdf.lastErrorText());
        return;
        }

    //  Encrypt with AES-256 and do not permit modifying.
    pdf.put_UserPassword("user-secret");
    pdf.put_OwnerPassword("owner-secret");
    CkJsonObject json = new CkJsonObject();
    json.UpdateBool("permissions.modify",false);
    CkJsonObject jsonOut = new CkJsonObject();
    success = pdf.Protection("encrypt",json,jsonOut);
    if (success == false) {
        Log.i(TAG, pdf.lastErrorText());
        return;
        }

    //  The encryption is still pending.  SignPdf applies it first and signs the encrypted result.
    success = pdf.SetSigningCert(cert);
    if (success == false) {
        Log.i(TAG, pdf.lastErrorText());
        return;
        }

    CkJsonObject sigOpts = new CkJsonObject();
    sigOpts.UpdateBool("invisibleSignature",true);
    sigOpts.UpdateInt("signingCertificateV2",1);
    sigOpts.UpdateInt("signingTime",1);
    success = pdf.SignPdf(sigOpts,"qa_output/memo_encrypted_signed.pdf");
    if (success == false) {
        Log.i(TAG, pdf.lastErrorText());
        return;
        }

    //  The result is encrypted and signed.
    CkPdf check = new CkPdf();
    check.put_UserPassword("user-secret");
    success = check.LoadFile("qa_output/memo_encrypted_signed.pdf");
    if (success == false) {
        Log.i(TAG, check.lastErrorText());
        return;
        }

    CkJsonObject empty = new CkJsonObject();
    CkJsonObject info = new CkJsonObject();
    success = check.Protection("getInfo",empty,info);
    if (success == false) {
        Log.i(TAG, check.lastErrorText());
        return;
        }

    Log.i(TAG, "algorithm: " + info.stringOf("loaded.algorithm"));
    Log.i(TAG, "signatures: " + String.valueOf(check.get_NumSignatures()));
    CkJsonObject sigInfo = new CkJsonObject();
    boolean verified = check.VerifySignature(0,sigInfo);
    Log.i(TAG, "signature verifies: " + String.valueOf(verified));

    //  Signing an encrypted PDF.  This one was opened with only the user password, and its
    //  permissions do not allow modifying, so another signature is refused.
    success = check.SetSigningCert(cert);
    if (success == false) {
        Log.i(TAG, check.lastErrorText());
        return;
        }

    success = check.SignPdf(sigOpts,"qa_output/memo_signed_twice.pdf");
    if (success == false) {
        Log.i(TAG, "A second signature was refused: the permissions do not allow it.");
        }

    //  Loaded with the owner password, the same PDF can be signed.  It stays encrypted, and the
    //  first signature stays valid because the new one is added as an incremental update.
    CkPdf owner = new CkPdf();
    owner.put_UserPassword("user-secret");
    owner.put_OwnerPassword("owner-secret");
    success = owner.LoadFile("qa_output/memo_encrypted_signed.pdf");
    if (success == false) {
        Log.i(TAG, owner.lastErrorText());
        return;
        }

    success = owner.SetSigningCert(cert);
    if (success == false) {
        Log.i(TAG, owner.lastErrorText());
        return;
        }

    success = owner.SignPdf(sigOpts,"qa_output/memo_signed_twice.pdf");
    if (success == false) {
        Log.i(TAG, owner.lastErrorText());
        return;
        }

    CkPdf twice = new CkPdf();
    twice.put_UserPassword("user-secret");
    success = twice.LoadFile("qa_output/memo_signed_twice.pdf");
    if (success == false) {
        Log.i(TAG, twice.lastErrorText());
        return;
        }

    Log.i(TAG, "signatures after signing with owner rights: " + String.valueOf(twice.get_NumSignatures()));
    verified = twice.VerifySignature(0,sigInfo);
    Log.i(TAG, "first signature still verifies: " + String.valueOf(verified));
    verified = twice.VerifySignature(1,sigInfo);
    Log.i(TAG, "second signature verifies: " + String.valueOf(verified));

    //  Sample output:

    //  algorithm: aes-256
    //  signatures: 1
    //  signature verifies: True
    //  A second signature was refused: the permissions do not allow it.
    //  signatures after signing with owner rights: 2
    //  first signature still verifies: True
    //  second signature verifies: True

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}