WhatsApp, the widely popular iOS and Android messaging app recently added end-to-end encryption by default to mobile, a move that will help secure millions of users.

WhatsApp improvement is in result of the company’s latest partnership with Open Whisper Systems, the open source secure text and and mobile encryption company started by security expert, Moxie Marlinspike. Open Whisper Systems was acquired by Twitter back in 2011, Marlinspike stayed on board for two years before leaving the company. Moxie has been working on encryption systems for years, and made a recent move towards WhatsApp, helping the company implement end-to-end encryption for their users.

The current WhatsApp advancement is only available to Android users, and only works for one-on-one chats, not group messages.

“The most recent WhatsApp Android client release includes support for the TextSecure encryption protocol, and billions of encrypted messages are being exchanged daily. The WhatsApp Android client does not yet support encrypted messaging for group chat or media messages, but we’ll be rolling out support for those next, in addition to support for more client platforms. We’ll also be surfacing options for key verification in clients as the protocol integrations are completed,” Open Whisper Systems said in their blog announcement.

WhatsApp has followed in the steps of many other large tech companies, implementing encryption to deter the NSA and other large corporations from spying on their users. Companies such as Google and Yahoo have begun encrypting communications in light of the revelations.

WhatsApp was recently purchased by Facebook for $19 billion back in February, due to Facebook’s not-so-private past, the application has been criticized for security and privacy issues since. After the recent advancement the company took, the company has once again received positive feedback from the security community.

The company’s choice moving towards encryption is one of the larger advancements, seeing as the application processes more than one billion texts per day.

A number of other encrypted mobile chat applications do exist, but according to the Verge, WhatsApp will be the largest app to implement such end-to-end encryption methods.

“WhatsApp runs on an incredible number of mobile platforms, so full deployment will be an incremental process as we add TextSecure protocol support into each WhatsApp client platform. We have a ways to go until all mobile platforms are fully supported, but we are moving quickly towards a world where all WhatsApp users will get end-to-end encryption by default,” Open Whisper Systems wrote.

Photo via Jan Persiel/Flickr [CC BY 2.0]