"Our team at Viber has been working hard to give you more control over your private conversations. Today we are taking another step in this direction by making your private communication even safer through end-to-end encryption, hidden chats and message deletion," Viber COO Michael Shmilov said in a blogpost.
He added that the company has been working on this for a long time and users can "confidently use Viber without fear of their messages being intercepted - whether it is in a one-to-one or group message, on a call, on desktop, mobile or tablet".
The development came close on the heels of a legal battle between Apple and FBI over the US agency's demand that the iPhone maker help unlock its mobile phones. Many Silicon Valley players had supported Apple citing that user data privacy needs to be respected.
According to Viber website, it has more than 600 million unique users in 193 countries. In April last year, the company had announced crossing the 40 million-user mark in India.
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Japan's Rakuten bought privately-held Viber from Israeli entrepreneur Talmon Marco for USD 900 million in February 2014. Viber's competitors include apps like LINE, Hike and WhatsApp.
Users can manually authenticate contacts to select they are "trusted" that changes the lock colour to green.
"If you ever see a red lock it means there is a problem with the authentication key. The breach may simply mean that a user has changed his or her primary phone. However, it can also indicate a man-in-the-middle-attack. To solve a possible breach state, the participant needs to be re-trusted," he said.