(Android™) AES and CHACHA20 Encrypt/Decrypt Text

Demonstrates the use of the new EncryptSb and DecryptSb methods introduced in Chilkat v9.5.0.67 to encrypt/decrypt the contents of StringBuilder objects.

Note: This example requires Chilkat v9.5.0.67 or greater.

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.

    boolean success;

    // First build a string to be encrypted
    CkStringBuilder sb = new CkStringBuilder();
    int i = 1;
    while (i < 10) {
        sb.AppendInt(i);
        sb.Append(" the quick brown fox jumped over the lazy dog.\r\n");
        i = i + 1;
        }

    Log.i(TAG, sb.getAsString());

    // The string to be encrypted looks like this:

    // 1 the quick brown fox jumped over the lazy dog.
    // 2 the quick brown fox jumped over the lazy dog.
    // 3 the quick brown fox jumped over the lazy dog.
    // 4 the quick brown fox jumped over the lazy dog.
    // 5 the quick brown fox jumped over the lazy dog.
    // 6 the quick brown fox jumped over the lazy dog.
    // ...

    CkCrypt2 crypt = new CkCrypt2();

    // Specify the encryption to be used.
    // First we'll do AES-128 CBC
    crypt.put_CryptAlgorithm("aes");
    crypt.put_CipherMode("cbc");
    crypt.put_KeyLength(128);

    String ivHex = "000102030405060708090A0B0C0D0E0F";
    crypt.SetEncodedIV(ivHex,"hex");

    String keyHex = "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F";
    crypt.SetEncodedKey(keyHex,"hex");

    // When EncryptSb is called, the contents of the source (sb)
    // remains unmodified.  The encrypted bytes are written into bdEncrypted.
    // If bdEncrypted already contained data, it is replaced with the encrypted bytes.
    CkBinData bdEncrypted = new CkBinData();
    success = crypt.EncryptSb(sb,bdEncrypted);
    if (success != true) {
        Log.i(TAG, crypt.lastErrorText());
        return;
        }

    // Examine the encrypted bytes:
    Log.i(TAG, bdEncrypted.getEncoded("base64_mime"));

    // Sample encrypted data:

    // 0DdNZ22ckMMJBiaKhAu3wUEfh16XW356NIUsDmNs/xwbHe/p1201OmpfzwXwKktkAefu2pckrBgC
    // df+1w8lRo+KAy5n5wlAgMGM/UrsVJsp0BmDPk1vaxKrmrGpSXOVCQs1n2+0atIs5YLiOG+Va3+Mi
    // EQNb4YK7bNMmvt0++irBxTiGnkx/RncfKwgkbBUpl2x7yV13MW6lapDT6Md0DKAMsTXFJYGeIdEf
    // g2uxDDQzI5gUOUHTMrXQ8paD/K76KKB9Jpp/kAM9z8g/d8KUmuphA7KI64d38xsgOmcITlbhlCQ2
    // PDkcU6RRzX0FUTUSMgQukhy0jkLZEjHX9poKJD+iJTOkcQUC3OqR9hKhSrvIgJN4lxdR71MheOoQ
    // 2wmvRdq+agTWWh333Vmb6J6yDV79aSpnqEDrA8Ks7Xzciol0gve91+JtVJlJKjWwEzWEU8GxF7Q8
    // eaWI70lsC5nTLGcbqgKu6gzkzHlHyHaE2FAQA/d5I2dvfsAYUQCza0Zdyw8mmTtHhlP2Tfxj1uPv
    // H4Q7BGuKnx3SWT2CnpbX4091w7KzLAztrbFBo/Tf9w8ZpgTK9k1ryfW9/xnk6rW6iQ==

    // Decrypt to restore back to the original:
    CkStringBuilder sbOriginal = new CkStringBuilder();
    success = crypt.DecryptSb(bdEncrypted,sbOriginal);
    if (success != true) {
        Log.i(TAG, crypt.lastErrorText());
        return;
        }

    // Examine the original data:
    Log.i(TAG, sbOriginal.getAsString());

    // ----------------------------------------------------------------------------------
    // To do chacha20 encryption, just change the settings:

    crypt.put_CryptAlgorithm("chacha20");
    crypt.put_KeyLength(256);
    // The initial count is the initial block counter for the chacha20 algorithm.
    // It can be any integer, but must be set to the same when decrypting.
    crypt.put_InitialCount(22);

    // EncryptSb completely replaces the contents of bdEncrypted.
    success = crypt.EncryptSb(sb,bdEncrypted);

    // However.. DecryptSb appends the decrypted text to whatever may
    // have already existed within sbOriginal.
    success = crypt.DecryptSb(bdEncrypted,sbOriginal);

    Log.i(TAG, "----");
    Log.i(TAG, "The original data should be here twice.  Once from the AES decrypt, and again from the chacha20 decrypt.");
    Log.i(TAG, sbOriginal.getAsString());
    Log.i(TAG, "Success.");

  }

  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."
  }
}