Firefox Nightly now supports encrypting the TLS Server Name Indication (SNI) extension, which helps prevent attackers on your network from learning your browsing history. You can enable encrypted SNI today and it will automatically work with any site that supports it. Currently, that means any site hosted by Cloudflare, but we’re hoping other providers will add ESNI support soon.
Although an increasing fraction of Web traffic is encrypted with HTTPS, that encryption isn’t enough to prevent network attackers from learning which sites you are going to. It’s true that HTTPS conceals the exact page you’re going to, but there are a number of ways in which the site’s identity leaks. This can itself be sensitive information: do you want the person at the coffee shop next to you to know you’re visiting cancer.org?
There are four main ways in which browsing history information leaks to the network: the TLS certificate message, DNS name resolution, the IP address of the server, and the TLS Server Name Indication extension. Fortunately, we’ve made good progress shutting down the first two of these: The new TLS 1.3 standard encrypts the server certificate by default and over the past several months, we’ve been exploring the use of DNS over HTTPS to protect DNS traffic. This is looking good and we are hoping to roll it out to all Firefox users over the coming months. The IP address remains a problem, but in many cases, multiple sites share the same IP address, so that leaves SNI. See more...