Describing the changes using the metaphor of transforming Facebook from a town square into a living room, Zuckerberg wrote: "As I think about the future of the internet, I believe a privacy-focused communications platform will become even more important than today's open platforms. Privacy gives people the freedom to be themselves and connect more naturally, which is why we build social networks."
Public trust in Facebook is at record lows, according to studies, the result of crushing privacy controversies last year as well as the misuse of user data that extend back more than a decade.
In a reputation score of 100 highly visible public companies, Facebook last year dropped from 51st to 94th, according to a Harris Poll published today in conjunction with the news organisation Axios. In a Pew Research Centre study from September, a quarter of the Facebook users polled said they deleted the app from their smartphones last year, and more than half said they adjusted their privacy settings.
Zuckerberg acknowledged the trust deficit in his post. "I understand that many people don't think Facebook can or would even want to build this kind of privacy-focused platform -- because frankly we don't currently have a strong reputation for building privacy protective services, and we've historically focused on tools for more open sharing," he wrote. "But we've repeatedly shown that we can evolve to build the services that people really want, including in private messaging and stories."
But the moves also appear to be strongly prompted by business considerations.
Facebook has grown from a single social network - Facebook - to what Zuckerberg refers to as a "family" of four apps, with Messenger, Instagram, and WhatsApp.
Facebook was long the star, but last year WhatsApp surpassed it in the number of people who use it on a monthly basis, according to industry reports. Zuckerberg recently began emphasising the number of people who use at least one of its products once a month - 2.7 billion people - rather than the 2.3 billion monthly users for Facebook alone. Users log onto messaging apps more frequently than the core social network, whose growth has flattened in the US and Europe.
In Zuckerberg's blog, he set out a vision for "interoperability," meaning that the changes would not only make messaging more private, they would allow people to message and communicate with one another across the company's apps.
Zuckerberg has routinely reaffirmed Facebook's commitment to privacy. But the difference in today's announcement were the structural changes Zuckerberg said he intends to make to Facebook's wide array of services - changes that he hopes will ensure that Facebook, with its damaged reputation and slowed growth, has a place in the future of social media.
He said the company would start with its messaging functionality. While WhatsApp has been end-to-end encrypted for years - meaning the data is scrambled so that outsiders, and even Facebook itself, cannot read the content of messages - Facebook's standalone Messenger app is not. Messaging within Facebook's Instagram app is also not encrypted.
Privacy advocates said Zuckerberg needs to go beyond touting encryption to provide concrete information about whether less data will be collected and used for Facebook's profits.
"Why does it always sound like we are witnessing a digital version of Ground Hog Day when Facebook yet again promises-when it's in a crisis-that it will do better," said Jeff Chester, Executive Director of the Centre for Digital Democracy, a non-profit privacy advocacy group in Washington. "Will it actually bring a change to how Facebook continually gathers data on its users in order to drive big profits?"
If Zuckerberg continues to encrypt more of Facebook's services, the company could run into more trouble internationally.
WhatsApp's encryption has got the service into bruising fights with governments in India and Brazil, two of Facebook's largest markets. Brazil has shut down WhatsApp on three different occasions when government officials asked for data that WhatsApp said it did not have. The Indian Government has also proposed breaking WhatsApp's encryption in order to make the data in it more traceable.
More fluid communication could also help Facebook achieve a goal that so far is has made little progress on: Making money off its messaging platforms.
The social network part of Facebook is still the main driver of the company's revenues because the platform is so heavily integrated with advertising. The company only recently introduced advertising on Messenger and also allows businesses to pay to reach customers on WhatsApp.
Zuckerberg suggested that the future would look different. After making messaging more secure, the company will "build more ways for people to interact on top of that, including calls, video chats, groups, stories, businesses, payments, commerce, and ultimately a platform for many other kinds of private services," he said.
