title: Send Encrypted messages over MQTT
body: <p>I am just researching about sending encrypted messages over MQTT. I encrypted a message with public key published over MQTT and the receiver will decrypt the message with private key.</p>
  
  <p>I tried with a RSA 512 bit key to encrypt data but on receiving end I received message in numbers.</p>
  
  <p>I have read about only certificate files that can provide security but this will ensure security for clients with same broker. Is there any other method so I can send encrypted data to other MQTT broker?</p>
  
  <p>Is there any method to encrypt and decrypt message, I am using Paho MQTT v3 and Java?</p>
  
  <p>Thanks</p>