Facebook Chief Executive Mark Zuckerberg announced changes to Facebook’s services on Wednesday, saying that he would spend the next several years reorienting the company’s apps toward encryption and privacy.

Zuckerberg outlined Facebook’s vision and principles around building a privacy-focused messaging and social networking platform.

He said that people should have simple, intimate places where they have clear control over who can communicate with them and confidence that no one else can access what they share.

For private communications, he said that end-to-end encryption is required in order to prevent anyone — including Facebook — from seeing what people share on the company's services.

Zuckerberg didn’t explain how the move would affect Facebook’s advertising business. Encrypted conversations could limit Facebook’s ability to send targeted advertisements.

Regulators meanwhile have called for Facebook to increase moderation of user content, but more encryption would make it difficult to view and track problematic posts.

He also said that people should not have to worry about what they share coming back to hurt them later. So Facebook promised not to keep messages or stories around for longer than necessary to deliver the service or longer than people want them.

Regarding safety, Zuckerberg promised to do everything possible to keep people safe on the company's services, within the limits of what’s possible in an encrypted service.

He also called for interoperability, saying that people should be able to use any of Facebook's apps to reach their friends, and they should be able to communicate across networks easily and securely. That would involve making it possible to send messages between the different properties Facebook owns, including WhatsApp and Instagram, which would make it easier for Facebook to merge the data on users’ identities.

He also underlined that Facebook will not store sensitive data in countries with weak records on human rights like privacy and freedom of expression in order to protect data from being improperly accessed.

Facebook’s core social network is structured around public conversation, but it also owns private messaging services WhatsApp and Messenger, which are closed networks.

Facebook is one of the biggest global players in private messaging with its WhatsApp, Messenger and Instagram, each used by more than 1 billion people. Only WhatsApp fully secures conversations from all outsiders, including Facebook itself.

The announcement, in the midst of a crisis that Facebook is facing over the loss of public trust, comes with major risks and is also likely to be treated skeptically. Lawmakers, users and investors have expressed concerns over the last two years that Facebook is not doing enough to safeguard user data after a series of breaches and privacy bugs. Zuckerberg has promised to protect privacy before, but the company has landed itself in controversy.

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.”