I am new to messaging world and started using Nanomsg library in my application. I want to know whether the messages are encrypted by default between the server and the client by the Nanomsg library. If not, how can I add encryption to secure the messages between the communicating nodes?
The payload of the message is not encrypted. You can add encryption and decryption for payload into the client and server. A very simple encryption is described here Simply encrypt a string in C