Facebook Inc. Chief Executive Mark Zuckerberg announced sweeping changes to his company’s services Wednesday, saying he would spend the next several years reorienting the social media giant’s apps toward encryption and privacy.

The moves — which Zuckerberg, in a blog post, outlined in broad strokes rather than as a set of specific product changes — would shift the company’s focus from a social network in which people widely broadcast information to one in which people communicate with smaller groups, with their content disappearing after a short period of time, Zuckerberg said. Facebook’s core social network is structured around public conversation, but it also owns private messaging services WhatsApp and Messenger, which are closed networks. Instagram, Facebook’s photo-sharing platform, has also seen huge growth thanks to ephemeral messaging.

Disappearing messages became popular this decade with Snap Inc.’s Snapchat app. Facebook has rolled out several Snapchat-like features in recent years.

Facebook’s announcement, in the midst of a crisis the company is facing over the loss of public trust and declining growth, comes with major risks and is likely to be treated skeptically. Zuckerberg has promised to protect privacy before, but the company has landed itself in controversy after controversy. Many governments also oppose encryption, and Facebook may end up getting blocked in some foreign countries as a result of the move — a risk Zuckerberg acknowledged in his post. The changes may also make it harder for Facebook to detect misinformation and other abuse of its platforms.

Zuckerberg described the changes using the metaphor of transforming Facebook from a town square into a living room. “Privacy gives people the freedom to be themselves and connect more naturally, which is why we build social networks,” he wrote.

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 extending back more than a decade. In a reputation score of 100 highly visible public companies, Facebook dropped last year from 51st to 94th, according to a Harris Poll published Wednesday in conjunction with the news organization Axios.

Zuckerberg acknowledged the trust deficit Wednesday. But the moves also appear to be strongly prompted by business considerations. The company has grown from a single social network — Facebook — to a collection of four apps. 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 emphasizing the number of people who use at least one of its products once a month — 2.7 billion — rather than the Facebook social network’s 2.3 billion. Users log onto messaging apps more frequently than the core social network, whose growth has flattened in the U.S. and Europe.

In Zuckerberg’s blog post, he set out a vision for “interoperability,” meaning the changes would not only make messaging more private, they also would enable people to message and communicate with one another across the company’s apps.

WhatsApp has been end-to-end encrypted for years — meaning the data are scrambled so that outsiders, and even Facebook itself, cannot read the content of messages — but Facebook’s stand-alone 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 profit.

“Why does it always sound like we are witnessing a digital version of ‘Groundhog Day’ when Facebook yet again promises — when it’s in a crisis — that it will do better,” said Jeff Chester, executive director of the Center for Digital Democracy, a nonprofit 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 gotten 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 it 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 revenue because the platform is so heavily integrated with advertising.

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.

Dwoskin writes for the Washington Post.