In Viber, as a part of their security initiatives, all chats, whether they are 1-on-1 or group chats, are secured by end-to-end encryption.
This means that only the people part of those conversations can see them as the data is scrambled from the moment it is sent to the device to when it reaches the device.
The platforms this encryption covers are:
• IOS/Android - version 6.0 and further
• Desktop - version 6.0 and further
• Windows 10 - all versions available
The text between the phones involved is like a code that only the two phones can understand, thereby offering greater security.