I will discuss Talek, a private publish-subscribe protocol. With Talek, application developers can send and synchronize data through the cloud without revealing any information about data contents or communication patterns of application users. The protocol is designed with provable security guarantees and practical performance, 3-4 orders of magnitude better throughput than other systems with comparable security goals. I will also discuss Radiatus, a security-focused web framework to protect web apps against external intrusions, and uProxy, a Internet censorship circumvention tool in deployment today.