Save private key https://ethereum.stackexchange.com/questions/96336/how-to-hide-the-private-key-for-sign-trnx-with-nodejs?newreg=d4da6f810a864b0cbe8afb5b825b6905 https://stackoverflow.com/questions/60360298/is-it-secure-way-to-store-private-values-in-env-file
remove : express-session (use jwt)