How to use javax.crypto

private static boolean supportsClone(Mac mac) {
 try {
  mac.clone();
  return true;
 } catch (CloneNotSupportedException e) {
  return false;
 }
}

@Override
public int read(byte[] buffer, int offset, int length)
    throws IOException {
  return _cipherIn.read(buffer, offset, length);
}

@Override
public void write(byte[] buffer, int offset, int length)
    throws IOException {
  _cipherOut.write(buffer, offset, length);
}

public CombinedCipherOutputStream(OutputStream out, Cipher asym, String algorithm) throws IOException, GeneralSecurityException {
  super(out);
  // create a new symmetric cipher key used for this stream
  String keyAlgorithm = getKeyAlgorithm(algorithm);
  SecretKey symKey = KeyGenerator.getInstance(keyAlgorithm).generateKey();
  // place the symmetric key by encrypting it with asymmetric cipher
  out.write(asym.doFinal(symKey.getEncoded()));
  // the rest of the data will be encrypted by this symmetric cipher
  Cipher sym = Secret.getCipher(algorithm);
  sym.init(Cipher.ENCRYPT_MODE,symKey, keyAlgorithm.equals(algorithm) ? null : new IvParameterSpec(symKey.getEncoded()));
  super.out = new CipherOutputStream(out,sym);
}

/**
 * Upgrades a connection with transport encryption by the specified symmetric cipher.
 *
 * @return
 *      A new {@link Connection} object that includes the transport encryption.
 */
public Connection encryptConnection(SecretKey sessionKey, String algorithm) throws IOException, GeneralSecurityException {
  Cipher cout = Cipher.getInstance(algorithm);
  cout.init(Cipher.ENCRYPT_MODE, sessionKey, new IvParameterSpec(sessionKey.getEncoded()));
  CipherOutputStream o = new CipherOutputStream(out, cout);
  Cipher cin = Cipher.getInstance(algorithm);
  cin.init(Cipher.DECRYPT_MODE, sessionKey, new IvParameterSpec(sessionKey.getEncoded()));
  CipherInputStream i = new CipherInputStream(in, cin);
  return new Connection(i,o);
}

private static Cipher toCipher(RSAKey key, int mode) throws GeneralSecurityException {
  Cipher cipher = Cipher.getInstance("RSA");
  cipher.init(mode, (Key)key);
  return cipher;
}

private byte[] generateKey() throws NoSuchAlgorithmException {
  KeyGenerator keygen = KeyGenerator.getInstance("AES");
  keygen.init(128);
  byte[] key = keygen.generateKey().getEncoded();
  return key;
}

/**
 * Workaround for JENKINS-6459 / http://java.net/jira/browse/GLASSFISH-11862
 * This method uses specific provider selected via hudson.util.Secret.provider system property
 * to provide a workaround for the above bug where default provide gives an unusable instance.
 * (Glassfish Enterprise users should set value of this property to "SunJCE")
 */
public static Cipher getCipher(String algorithm) throws GeneralSecurityException {
  return PROVIDER != null ? Cipher.getInstance(algorithm, PROVIDER)
              : Cipher.getInstance(algorithm);
}

 /* Derive the key, given password and salt. */
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
KeySpec spec = new PBEKeySpec(password, salt, 65536, 256);
SecretKey tmp = factory.generateSecret(spec);
SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");

@Override
public void write(byte[] buffer, int offset, int length)
    throws IOException {
  _bodyOut.write(buffer, offset, length);
  _mac.update(buffer, offset, length);
}

  @Override
  public byte[] createIV() throws NoSuchAlgorithmException {
    KeyGenerator keygen = KeyGenerator.getInstance("AES");
    keygen.init(128);
    return keygen.generateKey().getEncoded();
  }
}

@Override
public int read()
    throws IOException {
  int ch = _bodyIn.read();
  if (ch < 0)
    return ch;
  _mac.update((byte) ch);
  return ch;
}

@Override
public void write(int ch)
    throws IOException {
  _cipherOut.write(ch);
}

@Override
public int read()
    throws IOException {
  return _cipherIn.read();
}

private static boolean supportsClone(Mac mac) {
 try {
  mac.clone();
  return true;
 } catch (CloneNotSupportedException e) {
  return false;
 }
}

@Override
public void write(int ch)
    throws IOException {
  _bodyOut.write(ch);
  _mac.update((byte) ch);
}

@Override
public int read(byte[] buffer, int offset, int length)
    throws IOException {
  int len = _bodyIn.read(buffer, offset, length);
  if (len < 0)
    return len;
  _mac.update(buffer, offset, len);
  return len;
}

@Override
protected void update(byte[] b, int off, int len) {
 checkNotDone();
 mac.update(b, off, len);
}

@Override
protected void update(byte b) {
 checkNotDone();
 mac.update(b);
}

@Override
protected void update(byte[] b) {
 checkNotDone();
 mac.update(b);
}