(Android™) Sign a Byte Array to Create an Opaque Signature in a Byte Array

Signs data contained in a byte array to produce an opaque signature (also in a byte array). An opaque signature is a PKCS7 signature (also known as CAdES) that embeds the signed data. Also shows how to verify the signature and extract the original data.

Chilkat Android™ Downloads Android™ Java Libraries Android C/C++ Libraries

// 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);

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

    CkCert cert = new CkCert();
    boolean success = cert.LoadPfxFile("qa_data/pfx/cert_test123.pfx","test123");
    if (success == false) {
        Log.i(TAG, cert.lastErrorText());
        return;
        }

    CkFileAccess fac = new CkFileAccess();

    CkByteData fileBytes = new CkByteData();
    success = fac.ReadEntireFile("qa_data/pdf/sample.pdf",fileBytes);
    if (fac.get_LastMethodSuccess() != true) {
        Log.i(TAG, fac.lastErrorText());
        return;
        }

    CkCrypt2 crypt = new CkCrypt2();

    success = crypt.SetSigningCert(cert);

    // We can sign any type of file.

    CkByteData sigBytes = new CkByteData();
    success = crypt.OpaqueSignBytes(fileBytes,sigBytes);
    if (crypt.get_LastMethodSuccess() != true) {
        Log.i(TAG, crypt.lastErrorText());
        return;
        }

    success = fac.WriteEntireFile("qa_output/sample.pdf.p7m",sigBytes);
    if (fac.get_LastMethodSuccess() != true) {
        Log.i(TAG, fac.lastErrorText());
        return;
        }

    // We can verify the opaque signature and extract the original data like this
    CkByteData originalData = new CkByteData();
    success = crypt.OpaqueVerifyBytes(sigBytes,originalData);
    if (crypt.get_LastMethodSuccess() != true) {
        Log.i(TAG, crypt.lastErrorText());
        return;
        }

    success = fac.WriteEntireFile("qa_output/sample.pdf",originalData);
    if (fac.get_LastMethodSuccess() != true) {
        Log.i(TAG, fac.lastErrorText());
        return;
        }

    Log.i(TAG, "Signature is verified and the original data was extracted.");

  }

  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."
  }
}