Some Crypto in Anger - using JCE and BouncyCastle JCE Provider

OutputStream out = new ObjectOutputStream(new FileOutputStream("encrypter.key"));

// Serialize the secret to a byte array

ByteArrayOutputStream bos = new ByteArrayOutputStream();

ObjectOutput objectOutput = new ObjectOutputStream(bos);
 objectOutput.writeObject(secret);

objectOutput.close();

// Get the bytes of the serialized object and use them as the inputstream

InputStream is = new ByteArrayInputStream(bos.toByteArray());
streamEncrypter.encrypt(is, out);