(Java) JWE using AES Key Wrap and AES_128_CBC_HMAC_SHA_256

This example duplicates the example A.3 in RFC 7516 for JSON Web Encryption (JWE).

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

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    // 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.";

    CkJwe jwe = new CkJwe();

    // First build the JWE Protected Header: {"alg":"A128KW","enc":"A128CBC-HS256"}
    CkJsonObject jweProtHdr = new CkJsonObject();
    jweProtHdr.AppendString("alg","A128KW");
    jweProtHdr.AppendString("enc","A128CBC-HS256");
    jwe.SetProtectedHeader(jweProtHdr);

    System.out.println("JWE Protected Header: " + jweProtHdr.emit());
    System.out.println("--");

    // The example A.3 in RFC 7516 uses the following 128-bit AES key,
    // specified in JWK (JSON Web Key) format:
    //      {"kty":"oct",
    //       "k":"GawgguFyGrWKav7AX4VKUg"
    //      }
    // This is just a way of saying: The key type ("kty") is 
    // a bunch of octets ("k") in base64url encoding.
    // We can simply set the AES wrapping key like this:
    String aesWrappingKey = "GawgguFyGrWKav7AX4VKUg";
    jwe.SetWrappingKey(0,aesWrappingKey,"base64url");

    // Encrypt and return the JWE:
    String strJwe = jwe.encrypt(plaintext,"utf-8");
    if (jwe.get_LastMethodSuccess() != true) {
        System.out.println(jwe.lastErrorText());
        return;
        }

    // Show the JWE we just created:
    System.out.println(strJwe);

    // Decrypt the JWE that was just produced.
    // 1) Load the JWE.
    // 2) Set the AES wrapping key.
    // 3) Decrypt.
    CkJwe jwe2 = new CkJwe();
    success = jwe2.LoadJwe(strJwe);
    if (success != true) {
        System.out.println(jwe2.lastErrorText());
        return;
        }

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

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

    System.out.println("original text: ");
    System.out.println(originalPlaintext);

    // ---------------------------------------------------------------------------------
    // It should also be possible to decrypt the JWE as shown in RFC 7516, Appendix A.3.7
    // because it was produced using the same AES Wrap key.

    CkStringBuilder sbJwe = new CkStringBuilder();
    sbJwe.Append("eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.");
    sbJwe.Append("6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ.");
    sbJwe.Append("AxY8DCtDaGlsbGljb3RoZQ.");
    sbJwe.Append("KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY.");
    sbJwe.Append("U0m_YmjN04DJvceFICbCVQ");

    success = jwe2.LoadJweSb(sbJwe);
    if (success != true) {
        System.out.println(jwe2.lastErrorText());
        return;
        }

    jwe2.SetWrappingKey(0,aesWrappingKey,"base64url");

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

    System.out.println(originalPlaintext);
  }
}