@porus yup, thought I was right, this is taken from their site: “Protect your communication in transit and on your phone. Silence (formerly SMSSecure) is a full replacement for the default text messaging application: all messages are encrypted locally and messages to other Silence users are encrypted over the air.”
So it only encrypts locally, which again is pointless as most modern phones are encrypted anyway. Only encrypt ed in transit when recipient is using the app also.