PrivateKey priKey = keyPair.getPrivate();
PublicKey pubKey = keyPair.getPublic();
KeyGenerator keyGen = KeyGenerator.getInstance("DES", "BC");
Key wrapKey = keyGen.generateKey();
cipher.init(Cipher.WRAP_MODE, wrapKey);
byte[] wrappedKey = cipher.wrap(priKey);
cipher.init(Cipher.UNWRAP_MODE, wrapKey);
Key key = cipher.unwrap(wrappedKey, "RSA", Cipher.PRIVATE_KEY);