The decoupling principle: a practical privacy framework

The three decade struggle to ensure Internet data confidentiality---a key aspect of communications privacy---is finally behind us. Encryption is fast, secure, and standard in all browsers, modern transports, and major protocols. Yet it has long seemed that network privacy is not unified by core principles but a grab bag of techniques and ideas applied to an equally wide range of applications, contexts, layers of infrastructure, and software stacks. Here we attempt to distill a principle---one that is old but seldom discussed as such---for building privacy into Internet services. We explore what privacy properties are desirable and achievable when we apply this principle. We evaluate several classic systems and ones that have been recently deployed with this principle applied, and discuss future directions for network privacy building upon these efforts.