Viber offer one to one end encryption so that user data and information remain safe. It does not allow third party to reach your personal information for your safety. Therefore, it is important to have complete privacy while using the viber app. In case if you don’t see the chat encrypted message first check your Viber version. If it is not updated then firstly update it. it is important to have Viber version6.0 or higher to get one to one encryption.
To check your viber version open google play store if you are using android phone
Open viber by writing on search box on playstore
Now open viber messenger App
Now scroll down and click on the option "About This App"
Now scroll down and you can check the version of viber. In case if it is not updated you will get the option of update.
If your version is not 6.0 or above then you will not get one to one encryption so try to update your Viber to get complete privacy.