Zoom Video Communications pushed forward on Thursday in its effort to revamp its security, striking a deal with the New York attorney general's office to protect users' privacy and purchased secure messaging startup Keybase.

The company, which has faced backlash for failing to disclose that its service was not fully end-to-end encrypted said it planned to develop tools that will give more controls to meeting hosts and allow users to securely join a meeting and submit them to external review.

Zoom has been one of the big beneficiaries of coronavirus lockdowns, with millions of workers and students using its video platform as they work and study from home.

The company said it had bought Keybase, a secure messaging and file-sharing service, for an undisclosed price as it seeks engineering expertise to deliver more robust encryption for its conferencing platform.

Separately, New York's attorney general, Letitia James, announced an agreement with Zoom over a range of issues, including enhanced privacy for educational accounts and updates to Zoom's policy on abusive conduct.

Shares of Zoom were up 5 percent at $157, after rising earlier as much as 8 percent.

Zoom said it was preparing a draft design of its encryption policy to be released May 22, when it plans to host discussions with cryptographic experts and customers, and integrate feedback into a final design before rolling the feature out to users.

"We are also investigating mechanisms that would allow enterprise users to provide additional levels of authentication," Chief Executive Officer Eric Yuan wrote in the blog post.

Founded in 2014, Keybase is an encrypted messaging platform that allows users to securely swap data and cryptographically verify one another's identities on social media.

But while Zoom has seen an extraordinary jump in users, now numbering 300 million participants a day, since the coronavirus crisis forced millions of people and students to work from home, security has been an issue.

Concerns about the security of Zoom's platform have led companies including Elon Musk's SpaceX and Sweden's Ericsson to ban employees from using the platform. New York public schools had also restricted teachers and students from using the platform, though the ban was recently rescinded.

Zoom's security push is part of a 90-day plan that has included hiring former Facebook security chief Alex Stamos and other known industry figures while launching new versions of its software with better encryption. The campaign has generally won plaudits from security experts.

James, the New York attorney general, said her office and Zoom "have worked cooperatively and quickly to implement more stringent and robust protections for consumers, schools, and businesses."