Plans to boost security measures to Messenger and video chat in the following months.
Yahoo hopes to evade NSA spying after it beefed up the security of its data centres by encrypting all the traffic flowing between them.
The latest move fulfils chief executive Marissa Mayer’s assurance to encrypt all information transferred between its data centres by the end of March.
In addition to data centres, the search engine giant also activated encryption for a range of other services including mail between its own servers and other mail providers, and default encryption between users and its email service.
Yahoo CISO Alex Stamos said that the company is targeting to encrypt entire platform for all users at all time, by default.
"One of our biggest areas of focus in the coming months is to work with and encourage thousands of our partners across all of Yahoo’s hundreds of global properties to make sure that any data that is running on our network is secure," Stamos added.
"Our broader mission is to not only make Yahoo secure, but improve the security of the overall web ecosystem."
The internet major is also considering strengthening its security measures to Messenger and video chat in the following months.
"In addition to moving all of our properties to encryption by default, we will be implementing additional security measures such as HSTS, Perfect Forward Secrecy and Certificate Transparency over the coming months. This isn’t a project where we’ll ever check a box and be ‘finished’," Stamos said.
"Our fight to protect our users and their data is an on-going and critical effort.
"We will continue to work hard to deploy the best possible technology to combat attacks and surveillance that violate our users’ privacy."
Yahoo joined hands with eight other tech majors, including Google, Facebook, and Apple, demanding reforms to US surveillance programmes in December 2013.