- Add etcd key for secret exchange
- Add keyring and keyring mutex to mange the other hosts' secret
- Add UpdateKeyring() and GetKey() for an agent to use this
- Add watchSecret() to dynamically update changes on other hosts' secret
- Add compareAndSwapSecret() to chceck and upate the host's secret

- Encrypt a message by the corresponding host's public key before sending
- Decrypt a message by the private key after receiving

- Funtionize decapsulate() and encapsulate() to reduce complexity
- Create directory or folder if not exist
- Add logging to secutil
- Fix invalid MarshalPKCS8PrivateKey() to MarshalPKIXPublicKey()
- Fix wrong path parameter of LoadPublicKeyFromFile()
- Fix etcd key to watch the other hosts' secret
- Ignore secret files
- Do lint

- Add condition to encrypt and decrypt packets
- Display bytes length before and after encryption