(Java) JWE with Binary Data

Demonstrates how to create a JWE that contains a binary payload (such as a JPG image).

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;

    // Load a JPG file that will be the JWE payload.
    CkBinData jpgBytes = new CkBinData();
    success = jpgBytes.LoadFile("qa_data/jpg/starfish.jpg");
    // Make sure your app checks the success/failure of the call to LoadFile..
    System.out.println("Original JPG size = " + jpgBytes.get_NumBytes());

    CkJwe jwe = new CkJwe();

    CkJsonObject jweProtHdr = new CkJsonObject();
    jweProtHdr.AppendString("alg","A128KW");
    jweProtHdr.AppendString("enc","A128CBC-HS256");
    jwe.SetProtectedHeader(jweProtHdr);

    String aesWrappingKey = "GawgguFyGrWKav7AX4VKUg";
    jwe.SetWrappingKey(0,aesWrappingKey,"base64url");

    // Encrypt and return the JWE in sbJwe:
    CkStringBuilder sbJwe = new CkStringBuilder();
    success = jwe.EncryptBd(jpgBytes,sbJwe);
    if (success != true) {
        System.out.println(jwe.lastErrorText());
        return;
        }

    // Show the JWE:
    System.out.println(sbJwe.getAsString());
    System.out.println("size of JWE: " + sbJwe.get_Length());

    // ---------------------------------------------------------
    // Decrypt to get the original JPG file..

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

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

    // Decrypt.
    CkBinData jpgOriginal = new CkBinData();
    success = jwe2.DecryptBd(0,jpgOriginal);
    if (success != true) {
        System.out.println(jwe2.lastErrorText());
        return;
        }

    System.out.println("Decrypted JPG size = " + jpgOriginal.get_NumBytes());

    // Save the decrypted JPG to a file.
    success = jpgOriginal.WriteFile("qa_output/jwe_decrypted_starfish.jpg");

    System.out.println("success = " + success);

    // The output of this program, when tested, was:
    // Original JPG size = 6229
    // eyJhbGciOiJBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2In0.9YFz_wteV ... 7Et3hKhpxnKEXw
    // size of JWE: 8473
    // Decrypted JPG size = 6229
    // success = True
  }
}