(Java) Encrypt Already Existing Zip

To encrypt an already existing non-encrypted .zip, the application must open the .zip, set the encryption related properties, and then re-write.

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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 Zip API to have been previously unlocked.
    // See Unlock Chilkat Zip for sample code.

    CkZip zip = new CkZip();

    // Open an unencrypted .zip
    boolean success = zip.OpenZip("qa_data/zips/test.zip");
    if (success != true) {
        System.out.println(zip.lastErrorText());
        return;
        }

    // Unzip to a temp directory.
    int numFilesUnzipped = zip.Unzip("qa_output/tmp");
    if (numFilesUnzipped < 0) {
        System.out.println(zip.lastErrorText());
        return;
        }

    // Clear the zip object.
    zip.NewZip("qa_output/aesTest.zip");

    // Indicate that 128-bit AES encryption is to be used when writing the .zip
    zip.put_Encryption(4);
    zip.put_EncryptKeyLength(128);

    // Set the password.
    zip.put_EncryptPassword("secret");

    // Append the files.
    zip.put_AppendFromDir("qa_output/tmp");
    success = zip.AppendFiles("*.*",true);
    if (success != true) {
        System.out.println(zip.lastErrorText());
        return;
        }

    // Write the .zip and close it.
    success = zip.WriteZipAndClose();
    if (success != true) {
        System.out.println(zip.lastErrorText());
        return;
        }

    System.out.println("Success.");
  }
}