"HTTPS protects everyone, especially when you're using Wi-Fi access points," said Chester Wisniewski, senior security adviser at Sophos. "Before, it was really easy to have your Facebook account hijacked just by logging on a Wi-Fi network. Having HTTPS enabled also protects you when you're browsing from a mobile device, which people do daily."
This means that your browser now communicates with Facebook using a secure connection. You'll notice this in the address bar where there is a lock icon and "https" rather than "http" in the Web address.
Facebook first introduced the HTTPS browsing option two years ago. Facebook recommended that users who frequently accessed the social network from public Internet access points such as coffee shops, airports and schools enable this option, though it was voluntary. In November, the social network announced it would start rolling out HTTPS for all users in North America, followed by everywhere else.
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According to Scott Renfro, a software engineer at Facebook, more than a third of users enabled the feature following its introduction. HTTPS uses Transport Layer Security, formerly known as Secure Sockets Layer, and makes the communication between your browser and Facebook servers more secure, he said.
"Now that HTTPS is on by default, virtually all traffic from www.facebook.com and 80% of traffic to m.facebook.com uses a secure connection," Renfro said. "Our native apps for Android and iOS have long used HTTPS a well."
One priority for Facebook in converting all users to HTTPS was increasing the site's speed, Renfro said. Encrypted pages tend to take longer to load, which slows down performance. Facebook was able to avoid extra latency in most cases by upgrading its infrastructure and using abbreviated "handshakes," he said. "In addition to the network round trips necessary for your browser to talk to Facebook servers, HTTPS adds additional round trips for the handshake to set up the connection. A full handshake requires two additional round trips, while an abbreviated handshake requires just one additional round trip. An abbreviated handshake can only follow a successful full handshake," he said.
"For example," he continued, "if you're in Vancouver, where a round trip to Facebook's Prineville, Oregon, data center takes 20ms, then the full handshake only adds about 40ms, which probably isn't noticeable. However, if you're in Jakarta, where a round trip takes 300ms, a full handshake can add 600ms. When combined with an already slow connection, this additional latency on every request could be very noticeable and frustrating."
Other changes Facebook made include: a secure attribute for authentication cookies, which instructs the browser to only send these cookies on HTTPS requests; an insecure indicator cookie, which directs to HTTPS when no authentication cookies are present; and upgrading all apps to support HTTPS browsing.
"Turning on HTTPS by default is a dream come true, and something Facebook's traffic, network, security infrastructure, and security teams have worked on for years," Renfro said. "We're really happy with how much of Facebook's traffic is now encrypted, and we are even more excited about the future changes we're preparing to launch."