The new open-source project could serve as the basis for a future of apps with features as complex as Slack, Discord, or Google Docs—but with added protection against surveillance.

Signal, the most secure widely available messaging app, has become a go-to resource for journalists, leakers and other people concerned about privacy. But it’s not infallible. And its shortcomings and ...

LONDON — A magazine journalist’s account of being added to a group chat of U.S. national security officials coordinating plans for airstrikes has raised questions about how highly sensitive ...