(Android™) JWE with DEFLATE Compression

Demonstrates how to DEFLATE ("zip") compress the JWE payload prior to encryption.

Note: This example requires Chilkat v9.5.0.66 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 requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // Note: This example requires Chilkat v9.5.0.66 or greater.

    boolean success;
    // Create some plaintext to be encrypted.
    // This example will demonstrate with and without DEFLATE (zip) compression.
    CkStringBuilder sbPlainText = new CkStringBuilder();
    boolean bCrLf = true;
    String line = "Live long and prosper.";
    sbPlainText.AppendLine(line,bCrLf);
    sbPlainText.AppendLine(line,bCrLf);
    sbPlainText.AppendLine(line,bCrLf);
    sbPlainText.AppendLine(line,bCrLf);

    // The text to be encrypted:
    Log.i(TAG, sbPlainText.getAsString());

    CkJwe jwe = new CkJwe();

    // Build the JWE Protected Header: {"alg":"A128KW","enc":"A128CBC-HS256","zip":"DEF"}
    // The "zip":"DEF" parameter indicates that the plaintext payload should
    // be compressed prior to encryption.
    CkJsonObject jweProtHdr = new CkJsonObject();
    jweProtHdr.AppendString("alg","A128KW");
    jweProtHdr.AppendString("enc","A128CBC-HS256");
    jweProtHdr.AppendString("zip","DEF");
    jwe.SetProtectedHeader(jweProtHdr);

    // Set the AES key wrap key:
    String aesWrappingKey = "GawgguFyGrWKav7AX4VKUg";
    jwe.SetWrappingKey(0,aesWrappingKey,"base64url");

    // Encrypt and return the JWE in sbJweCompressed:
    CkStringBuilder sbJweCompressed = new CkStringBuilder();
    success = jwe.EncryptSb(sbPlainText,"utf-8",sbJweCompressed);
    if (success != true) {
        Log.i(TAG, jwe.lastErrorText());
        return;
        }

    // Show the compressed JWE:
    Log.i(TAG, sbJweCompressed.getAsString());
    Log.i(TAG, "size of compressed JWE: " + String.valueOf(sbJweCompressed.get_Length()));

    // Now create a JWE without compression.
    jweProtHdr.Delete("zip");
    // Make sure to update the shared protected header:
    jwe.SetProtectedHeader(jweProtHdr);

    CkStringBuilder sbJweUncompressed = new CkStringBuilder();
    success = jwe.EncryptSb(sbPlainText,"utf-8",sbJweUncompressed);
    if (success != true) {
        Log.i(TAG, jwe.lastErrorText());
        return;
        }

    // Show the uncompressed JWE:
    Log.i(TAG, sbJweUncompressed.getAsString());
    Log.i(TAG, "size of uncompressed JWE: " + String.valueOf(sbJweUncompressed.get_Length()));

    // Decrypting is the same whether compression is used or not.
    // The "zip" header in the JWE indicates that the payload should be 
    // automatically decompressed (inflated) after decrypting.
    CkJwe jwe2 = new CkJwe();
    success = jwe2.LoadJweSb(sbJweCompressed);
    if (success != true) {
        Log.i(TAG, jwe2.lastErrorText());
        return;
        }

    // Set the AES wrap key.
    jwe2.SetWrappingKey(0,aesWrappingKey,"base64url");

    // Decrypt (also automatically decompresses).
    CkStringBuilder sbOriginalText = new CkStringBuilder();
    success = jwe2.DecryptSb(0,"utf-8",sbOriginalText);
    if (success != true) {
        Log.i(TAG, jwe2.lastErrorText());
        return;
        }

    Log.i(TAG, "original text from compressed JWE: ");
    Log.i(TAG, sbOriginalText.getAsString());

    // -----------------------------------------------------------
    // Do the same with the uncompressed JWE

    success = jwe2.LoadJweSb(sbJweUncompressed);
    if (success != true) {
        Log.i(TAG, jwe2.lastErrorText());
        return;
        }

    // Set the AES wrap key.
    jwe2.SetWrappingKey(0,aesWrappingKey,"base64url");

    // Decrypt.
    sbOriginalText.Clear();
    success = jwe2.DecryptSb(0,"utf-8",sbOriginalText);
    if (success != true) {
        Log.i(TAG, jwe2.lastErrorText());
        return;
        }

    Log.i(TAG, "original text from uncompressed JWE: ");
    Log.i(TAG, sbOriginalText.getAsString());

    // ------------------------------------------------
    // The output of this example is:
    // (Note: Your output data will be different because the content encryption key is randomly generated.)

    // eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2IiwiemlwIjoiREVGIn0.xuW-pEAIdEUFnk10m8ocursvktO8Of9ByCCAt6LgKkkOtCWCUn1kQw.zpGj-9WVni3cQxyOuZbcGA.0hzP1myua3oYpUHwCIY_3edBUREbUpLaX6wYuJduOdI.Ppc6aEO3y3B8BJ1FKMPjlA
    // size of compressed JWE: 212
    // eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.N4KeyC7nnSFkieJOyE24_zKeuV_m7v5UKoJb1TgV4Yc_r2RzUPNvyA.6AEdyXSCKx-iMmUJyypSLg.QpixfyrwhGpmwUDp623viik4smPav7vwPLiC2r-V-jwnSfEH3mxWu6DbrIz3mixaqATwynmEBzVPxvS9jTXpSAGCnniib4_0WoPl3r_wF5tlsKOEe--jpNso-DKd1Tp8jJxj3JkFWt3IRnUUKGj17g.sBfDwFc5fzpaI-UW8-SW4g
    // size of uncompressed JWE: 303
    // original text from compressed JWE: 
    // Live long and prosper.
    // Live long and prosper.
    // Live long and prosper.
    // Live long and prosper.
    // 
    // original text from uncompressed JWE: 
    // Live long and prosper.
    // Live long and prosper.
    // Live long and prosper.
    // Live long and prosper.
    // 

  }

  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."
  }
}