Используйте приложение APKPure
Историческую версию Siccura Safe SMS можно получить на Android
Siccura Safe SMS
Siccura Safe SMS, an app for texting (SMS, MMS) is the perfect alternative to your stock Android messaging app.
It automatically encrypts your SMS to help you take control of your data.
Switch to Siccura Safe SMS as your default SMS App to have the most secure SMS experience ever.