Like it says right there in the README, in the very first sentence after the NEWS section: "SC4 is a web application that provides secure encrypted communicati

Like it says right there in the README, in the very first sentence after the NEWS section: "SC4 is a web application that provides secure encrypted communications and secure digital signatures. It is intended to eventually be a replacement for PGP/GPG." I honestly don't know how it could possibly have been made any clearer.