Setup

Generate client and server key pairs as follows:

openssl req -x509 -newkey rsa:2048 -days 3650 -nodes -keyout client-key.pem -out client-cert.pem

openssl req -x509 -newkey rsa:2048 -days 3650 -nodes -keyout server-key.pem -out server-cert.pem

Usage:

Run the client and server as follows:

./server 
./client <message to send to the server>

The server just echoes back whatever it receives from the client. Both sides
display the resultant plaintext as a character string.