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Android™

Create a JWS into a StringBuilder

See more JSON Web Signatures (JWS) Examples

Demonstrates Jws.CreateJwsSb, which creates a JWS and writes it into a StringBuilder.

Background. JWS (JSON Web Signature) integrity-protects a payload with a signature or MAC. The header alg names the algorithm; this example uses HMAC-SHA256 (HS256) with a symmetric MAC key.

Chilkat Android™ Downloads

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;

    CkJws jws = new CkJws();

    //  Set the protected header for signer 0, specifying the signature algorithm (alg).
    CkJsonObject header = new CkJsonObject();
    header.UpdateString("alg","HS256");
    success = jws.SetProtectedHeader(0,header);
    if (success == false) {
        Log.i(TAG, jws.lastErrorText());
        return;
        }

    //  Set the payload to be signed.
    boolean bIncludeBom = false;
    success = jws.SetPayload("This is the content to sign.","utf-8",bIncludeBom);
    if (success == false) {
        Log.i(TAG, jws.lastErrorText());
        return;
        }

    //  Provide the HMAC key (base64) for signer 0.  In production, obtain the key from a secure source
    //  rather than hard-coding it.
    String base64Key = "YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXowMTIzNDU=";
    success = jws.SetMacKey(0,base64Key,"base64");
    if (success == false) {
        Log.i(TAG, jws.lastErrorText());
        return;
        }

    //  Create the JWS and write it into a StringBuilder.
    CkStringBuilder sbJws = new CkStringBuilder();
    success = jws.CreateJwsSb(sbJws);
    if (success == false) {
        Log.i(TAG, jws.lastErrorText());
        return;
        }

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

  }

  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."
  }
}