(Android™) Streaming Encryption

Encrypt and decrypt using a stream.

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

    CkCrypt2 crypt = new CkCrypt2();

    // Setup encryption using the chacha20 algorithm...
    crypt.put_CryptAlgorithm("chacha20");
    crypt.put_KeyLength(256);
    crypt.put_EncodingMode("hex");
    String ivHex = "000000000000000000000002";
    crypt.SetEncodedIV(ivHex,"hex");
    crypt.put_InitialCount(42);
    String keyHex = "1c9240a5eb55d38af333888604f6b5f0473917c1402b80099dca5cbc207075c0";
    crypt.SetEncodedKey(keyHex,"hex");

    String plainText = "The quick brown fox jumped over the lazy dog.\r\n";

    CkStream stream = new CkStream();

    // We'll save the encrypted output in eStrings to demonstrate streaming decryption next.
    CkStringArray eStrings = new CkStringArray();

    // Start a background task that will encrypt a stream.
    CkTask task = crypt.EncryptStreamAsync(stream);
    boolean success = task.Run();

    // Write plainText to the stream, and read chacha20 encrypted text..
    String cipherText;
    int i;
    for (i = 1; i <= 10; i++) {
        // Note: An encryption algorithm's block size will cause buffering,
        // and therefore not every loop iteration will produce output.
        success = stream.WriteString(plainText);
        if (stream.get_DataAvailable() == true) {
            cipherText = stream.readBytesENC("hex");
            Log.i(TAG, cipherText);
            success = eStrings.Append(cipherText);
            }

        }

    // Tell the background task that the stream has ended.
    success = stream.WriteClose();

    // Let's make sure the background task finished.
    // It should already be the case that the task is finished.
    while ((task.get_Finished() != true)) {
        task.SleepMs(20);
        }

    // Get any remaining data available from the stream.
    if (stream.get_DataAvailable() == true) {
        cipherText = stream.readBytesENC("hex");
        Log.i(TAG, cipherText);
        success = eStrings.Append(cipherText);
        }

    if (task.get_TaskSuccess() != true) {
        Log.i(TAG, "async encryption failed:");
        Log.i(TAG, task.resultErrorText());
        success = false;
        }

    Log.i(TAG, "-- encrypt finished --");

    // Now decrypt to return the original.

    // Reset the stream object so it can be used again.
    stream.Reset();

    // Start a background task that will decrypt a stream.
    task = crypt.DecryptStreamAsync(stream);
    success = task.Run();

    int n = eStrings.get_Count();
    for (i = 0; i <= n - 1; i++) {
        success = stream.WriteBytesENC(eStrings.getString(i),"hex");
        if (stream.get_DataAvailable() == true) {
            plainText = stream.readString();
            Log.i(TAG, plainText);
            }

        }

    // Tell the background task that the stream has ended.
    success = stream.WriteClose();

    // Let's make sure the background task finished.
    // It should already be the case that the task is finished.
    while ((task.get_Finished() != true)) {
        task.SleepMs(20);
        }

    // Get any remaining data available from the stream.
    if (stream.get_DataAvailable() == true) {
        plainText = stream.readString();
        Log.i(TAG, plainText);
        }

    if (task.get_TaskSuccess() != true) {
        Log.i(TAG, "async decryption failed:");
        Log.i(TAG, task.resultErrorText());
        success = false;
        }

    Log.i(TAG, "-- decrypt finished --");

  }

  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."
  }
}