Android™

Adding Entropy to a PRNG

See more PRNG Examples

Demonstrates how system entropy is automatically added when the application does not explicitly add entropy prior to generating the 1st random data. Also demonstrates how additional entropy can be added at anytime during the lifetime of the PRNG object. 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 assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    success = false;

    CkPrng fortuna;

    //  The simplest way to use the Chilkat PRNG is to instantiate the object
    //  and generate random data.  This skips the explicit step of getting system entropy
    //  and adding it (via get AddEntropy method).  When no entropy is explicitly added,
    //  Chilkat will automatically add 32-bytes of system entropy on the first request
    //  for random data.

    //  Generate some random data.
    //  The 1st call to GenRandom implicitly adds 32 bytes of system entropy to seed the PRNG.
    Log.i(TAG, fortuna.genRandom(16,"hex"));

    //  Note: An application can get additional system entropy and add it at any point
    //  during the lifetime of the PRNG.  For example:
    Log.i(TAG, fortuna.genRandom(16,"hex"));
    Log.i(TAG, fortuna.genRandom(16,"hex"));
    Log.i(TAG, fortuna.genRandom(16,"hex"));
    success = fortuna.AddEntropy(fortuna.getEntropy(16,"hex"),"hex");
    Log.i(TAG, fortuna.genRandom(16,"hex"));
    Log.i(TAG, fortuna.genRandom(16,"hex"));
    Log.i(TAG, fortuna.genRandom(16,"hex"));
    success = fortuna.AddEntropy(fortuna.getEntropy(16,"hex"),"hex");
    Log.i(TAG, fortuna.genRandom(16,"hex"));
    Log.i(TAG, fortuna.genRandom(16,"hex"));
    Log.i(TAG, fortuna.genRandom(16,"hex"));
    success = fortuna.AddEntropy(fortuna.getEntropy(16,"hex"),"hex");
    Log.i(TAG, fortuna.genRandom(16,"hex"));
    Log.i(TAG, fortuna.genRandom(16,"hex"));
    Log.i(TAG, fortuna.genRandom(16,"hex"));

  }

  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."
  }
}