The reason your sketch generates such a large binary is simply that the protocols you are using are quite "fat. If you just want to read a stream of sensor data then raw UDP is a much better and faster way to do it.
Perhaps a more detailed explanation would provide more guidance of help. I agree that "secure" as in encrypted is rather out of the question on say an Uno or a Leonaro.
Tere have been several Arduino compatible 32 bit ARM Cortex boards released lately that may be able to do that. The Teensy 3 might be a candidate or the Galago.