# install dependencies
$ npm install
# create a .env file in the root of the project, and copy and paste the contents of .env.example into it and save it.
# Set Your APP_ID, USER_AES_KEY and USER_IV_KEY in the .env file.
# start server
$ npm run watch
# test the endpoints.. the available endpoints are
/encrypt
/decrypt
# And you're good to go!
For detailed explanation on how things work, check out (https://searchsecurity.techtarget.com/definition/Advanced-Encryption-Standard).