(Android™) Create JWS using the Flattened JSON Serialization Format

Creates a JSON Web Signature (JWS) containing 1 signature and output using the flattened JSON serialization format.

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.

    // The JWS to be created will contain one signature using an ECDSA key.

    CkStringBuilder sbEccJwk = new CkStringBuilder();
    sbEccJwk.Append("{\"kty\":\"EC\",");
    sbEccJwk.Append("\"crv\":\"P-256\",");
    sbEccJwk.Append("\"x\":\"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU\",");
    sbEccJwk.Append("\"y\":\"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0\",");
    sbEccJwk.Append("\"d\":\"jpsQnnGQmL-YBIffH1136cspYG6-0iY7X1fCE9-E9LI\"");
    sbEccJwk.Append("}");

    CkPrivateKey eccKey = new CkPrivateKey();
    // Note: This example loads the ECDSA key from JWK format.  Any format can be loaded
    // into the private key object. (See the online reference documentation..)
    boolean success = eccKey.LoadJwk(sbEccJwk.getAsString());
    if (success != true) {
        Log.i(TAG, eccKey.lastErrorText());
        return;
        }

    // ---------------------------------------------------
    // Prepare both a protected and unprotected header.

    CkJsonObject jwsProtHdr = new CkJsonObject();
    jwsProtHdr.AppendString("alg","ES256");

    CkJsonObject jwsUnprotHdr = new CkJsonObject();
    jwsUnprotHdr.AppendString("kid","myEcKey");

    // ---------------------------------------------------
    CkJws jws = new CkJws();

    jws.SetProtectedHeader(0,jwsProtHdr);
    jws.SetUnprotectedHeader(0,jwsUnprotHdr);

    jws.SetPrivateKey(0,eccKey);

    boolean bIncludeBom = false;
    String payloadStr = "In our village, folks say God crumbles up the old moon into stars.";
    jws.SetPayload(payloadStr,"utf-8",bIncludeBom);

    // ---------------------------------------------------
    // Create the JWS.
    // Indicate we prefer the non-compact, flattened serialization.
    jws.put_PreferCompact(false);
    jws.put_PreferFlattened(true);

    String jwsStr = jws.createJws();
    if (jws.get_LastMethodSuccess() != true) {
        Log.i(TAG, jws.lastErrorText());
        return;
        }

    // The jwsStr is contains the flattened JSON in the smallest possible size, which is a single line.
    // To get in human-readable format, load into a Chilkat JSON object and emit..
    CkJsonObject json = new CkJsonObject();
    json.Load(jwsStr);
    json.put_EmitCompact(false);
    Log.i(TAG, json.emit());

    // Sample output:

    // { 
    //   "payload": "SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu",
    //   "protected": "eyJhbGciOiJFUzI1NiJ9",
    //   "header": { 
    //     "kid": "myEcKey"
    //   },
    //   "signature": "b7V2UpDPytr-kMnM_YjiQ3E0J2ucOI9LYA7mt57vccrK1rb84j9areqgQcJwOA00aWGoz4hf6sMTBfobdcJEGg"
    // }

  }

  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."
  }
}