Simple Secure Storage Service (S4) is Least Authority's verifiably secure off-site backup system for individuals and businesses. We never see your data, you can always see our code. Least Authority was formed in 2011 to create freedom-compatible technologies and moved to Berlin in 2016. We are a small team who believe that freedom matters in Internet technology. You can take advantage of online services while retaining control over your own data. We're here to make it easy. Our mission is to build an affordable, ethical, usable, and lasting data storage solution. We believe this requires Free and Open Source software, end-to-end cryptography, user-friendly interfaces, and a sustainable economic model. We run a verifiably-secure cloud backup system, S4 - Simple Secure Storage Service. We also perform security audits and have done it for a variety of open-source projects, including CryptoCat, GlobalLeaks, SpiderOak, & Ooni. We were hired by Ethereum to perform an incentive analysis on the proof-of-work puzzle, Ethash, and the gas mechanism.