(Android™) JWE using RSAES-PKCS1-v1_5 and AES_128_CBC_HMAC_SHA_256

This example duplicates the example A.2 in RFC 7516 for JSON Web Encryption (JWE).

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;
    String plaintext = "Live long and prosper.";

    // First build the JWE Protected Header.
    // We want to build this: {"alg":"RSA1_5","enc":"A128CBC-HS256"}
    CkJsonObject jweProtHdr = new CkJsonObject();
    jweProtHdr.AppendString("alg","RSA1_5");
    jweProtHdr.AppendString("enc","A128CBC-HS256");
    Log.i(TAG, "JWE Protected Header: " + jweProtHdr.emit());
    Log.i(TAG, "--");

    // The specific RSA key used in the A.2 example is the following JWK:
    CkStringBuilder sbJwk = new CkStringBuilder();
    sbJwk.Append("{\"kty\":\"RSA\",");
    sbJwk.Append("\"n\":\"sXchDaQebHnPiGvyDOAT4saGEUetSyo9MKLOoWFsueri23bOdgWp4Dy1Wl");
    sbJwk.Append("UzewbgBHod5pcM9H95GQRV3JDXboIRROSBigeC5yjU1hGzHHyXss8UDpre");
    sbJwk.Append("cbAYxknTcQkhslANGRUZmdTOQ5qTRsLAt6BTYuyvVRdhS8exSZEy_c4gs_");
    sbJwk.Append("7svlJJQ4H9_NxsiIoLwAEk7-Q3UXERGYw_75IDrGA84-lA_-Ct4eTlXHBI");
    sbJwk.Append("Y2EaV7t7LjJaynVJCpkv4LKjTTAumiGUIuQhrNhZLuF_RJLqHpM2kgWFLU");
    sbJwk.Append("7-VTdL1VbC2tejvcI2BlMkEpk1BzBZI0KQB0GaDWFLN-aEAw3vRw\",");
    sbJwk.Append("\"e\":\"AQAB\",");
    sbJwk.Append("\"d\":\"VFCWOqXr8nvZNyaaJLXdnNPXZKRaWCjkU5Q2egQQpTBMwhprMzWzpR8Sxq");
    sbJwk.Append("1OPThh_J6MUD8Z35wky9b8eEO0pwNS8xlh1lOFRRBoNqDIKVOku0aZb-ry");
    sbJwk.Append("nq8cxjDTLZQ6Fz7jSjR1Klop-YKaUHc9GsEofQqYruPhzSA-QgajZGPbE_");
    sbJwk.Append("0ZaVDJHfyd7UUBUKunFMScbflYAAOYJqVIVwaYR5zWEEceUjNnTNo_CVSj");
    sbJwk.Append("-VvXLO5VZfCUAVLgW4dpf1SrtZjSt34YLsRarSb127reG_DUwg9Ch-Kyvj");
    sbJwk.Append("T1SkHgUWRVGcyly7uvVGRSDwsXypdrNinPA4jlhoNdizK2zF2CWQ\",");
    sbJwk.Append("\"p\":\"9gY2w6I6S6L0juEKsbeDAwpd9WMfgqFoeA9vEyEUuk4kLwBKcoe1x4HG68");
    sbJwk.Append("ik918hdDSE9vDQSccA3xXHOAFOPJ8R9EeIAbTi1VwBYnbTp87X-xcPWlEP");
    sbJwk.Append("krdoUKW60tgs1aNd_Nnc9LEVVPMS390zbFxt8TN_biaBgelNgbC95sM\",");
    sbJwk.Append("\"q\":\"uKlCKvKv_ZJMVcdIs5vVSU_6cPtYI1ljWytExV_skstvRSNi9r66jdd9-y");
    sbJwk.Append("BhVfuG4shsp2j7rGnIio901RBeHo6TPKWVVykPu1iYhQXw1jIABfw-MVsN");
    sbJwk.Append("-3bQ76WLdt2SDxsHs7q7zPyUyHXmps7ycZ5c72wGkUwNOjYelmkiNS0\",");
    sbJwk.Append("\"dp\":\"w0kZbV63cVRvVX6yk3C8cMxo2qCM4Y8nsq1lmMSYhG4EcL6FWbX5h9yuv");
    sbJwk.Append("ngs4iLEFk6eALoUS4vIWEwcL4txw9LsWH_zKI-hwoReoP77cOdSL4AVcra");
    sbJwk.Append("Hawlkpyd2TWjE5evgbhWtOxnZee3cXJBkAi64Ik6jZxbvk-RR3pEhnCs\",");
    sbJwk.Append("\"dq\":\"o_8V14SezckO6CNLKs_btPdFiO9_kC1DsuUTd2LAfIIVeMZ7jn1Gus_Ff");
    sbJwk.Append("7B7IVx3p5KuBGOVF8L-qifLb6nQnLysgHDh132NDioZkhH7mI7hPG-PYE_");
    sbJwk.Append("odApKdnqECHWw0J-F0JWnUd6D2B_1TvF9mXA2Qx-iGYn8OVV1Bsmp6qU\",");
    sbJwk.Append("\"qi\":\"eNho5yRBEBxhGBtQRww9QirZsB66TrfFReG_CcteI1aCneT0ELGhYlRlC");
    sbJwk.Append("tUkTRclIfuEPmNsNDPbLoLqqCVznFbvdB7x-Tl-m0l_eFTj2KiqwGqE9PZ");
    sbJwk.Append("B9nNTwMVvH3VRRSLWACvPnSiwP8N5Usy-WRXS-V7TbpxIhvepTfE0NNo\"");
    sbJwk.Append("}");

    // Load this JWK into a Chilkat private key object.
    CkPrivateKey rsaPrivKey = new CkPrivateKey();
    success = rsaPrivKey.LoadJwk(sbJwk.getAsString());
    if (success != true) {
        Log.i(TAG, rsaPrivKey.lastErrorText());
        return;
        }

    // The public key is used to encrypt (i.e. create the JWE), 
    // and the private key is used to decrypt.
    // The RSA public key is simply a subset of the private key.  The RSA public key
    // is composed of the "n" and "e" members shown above.  These are also known as the
    // modulus and exponent.
    // We can simply get the public key object from the private key object
    CkPublicKey rsaPubKey = rsaPrivKey.GetPublicKey();

    // Create the JWE...
    CkJwe jwe = new CkJwe();
    jwe.SetProtectedHeader(jweProtHdr);
    jwe.SetPublicKey(0,rsaPubKey);

    String strJwe = jwe.encrypt(plaintext,"utf-8");
    if (jwe.get_LastMethodSuccess() != true) {
        Log.i(TAG, jwe.lastErrorText());
        return;
        }

    // Show the JWE we just created:
    Log.i(TAG, strJwe);

    // Note: The RSA PKCS1_V1_5 padding uses random value, and the results
    // will be different each time.  However, each result should be successfully
    // decrypting if using the correct RSA private key.

    // Let's decrypt the JWE that was just produced.
    // Do the following to decrypt a JWE:
    // 1) Load the JWE.
    // 2) Set the private key for decryption.
    // 3) Decrypt.
    CkJwe jwe2 = new CkJwe();
    success = jwe2.LoadJwe(strJwe);
    if (success != true) {
        Log.i(TAG, jwe2.lastErrorText());
        return;
        }

    // Provide the RSA private key for decryption.
    // (The JWE was encrypted for a single recipient at index 0.)
    jwe2.SetPrivateKey(0,rsaPrivKey);

    // Decrypt.
    String originalPlaintext = jwe2.decrypt(0,"utf-8");
    if (jwe2.get_LastMethodSuccess() != true) {
        Log.i(TAG, jwe2.lastErrorText());
        return;
        }

    Log.i(TAG, "original text: ");
    Log.i(TAG, originalPlaintext);

    // ---------------------------------------------------------------------------------
    // It should also be possible to decrypt the JWE as shown in RFC 7516, Appendix A.2.7
    // because it was produced using the same RSA key.

    CkStringBuilder sbJwe = new CkStringBuilder();
    sbJwe.Append("eyJhbGciOiJSU0ExXzUiLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.");
    sbJwe.Append("UGhIOguC7IuEvf_NPVaXsGMoLOmwvc1GyqlIKOK1nN94nHPoltGRhWhw7Zx0-kFm");
    sbJwe.Append("1NJn8LE9XShH59_i8J0PH5ZZyNfGy2xGdULU7sHNF6Gp2vPLgNZ__deLKxGHZ7Pc");
    sbJwe.Append("HALUzoOegEI-8E66jX2E4zyJKx-YxzZIItRzC5hlRirb6Y5Cl_p-ko3YvkkysZIF");
    sbJwe.Append("NPccxRU7qve1WYPxqbb2Yw8kZqa2rMWI5ng8OtvzlV7elprCbuPhcCdZ6XDP0_F8");
    sbJwe.Append("rkXds2vE4X-ncOIM8hAYHHi29NX0mcKiRaD0-D-ljQTP-cFPgwCp6X-nZZd9OHBv");
    sbJwe.Append("-B3oWh2TbqmScqXMR4gp_A.");
    sbJwe.Append("AxY8DCtDaGlsbGljb3RoZQ.");
    sbJwe.Append("KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.");
    sbJwe.Append("9hH0vgRfYgPnAHOd8stkvw");

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

    // Provide the RSA private key for decryption.
    jwe2.SetPrivateKey(0,rsaPrivKey);

    // Decrypt.
    originalPlaintext = jwe2.decrypt(0,"utf-8");
    if (jwe2.get_LastMethodSuccess() != true) {
        Log.i(TAG, jwe2.lastErrorText());
        return;
        }

    Log.i(TAG, originalPlaintext);

  }

  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."
  }
}