Prevent scrambled SMS: Indicate maximum size of message
Created by: SecUpwN
Hi there! I feel a little strange opening yet another Issue on your wonderful fork, but I just cannot help it since this is something TextSecure lacks as well and has always bugged the hell outa me:
When sending a large message, which is longer than 3+ SMS (one SMS contains 160 characters), SMSSecure and TextSecure is sending out the huge message without any complaint and also indicating that it was delivered, but the receiver gets multiple falsely encrypted messages, while not even one sentence is readable. Note: I cannot specify the "minimal" number of SMS that have to be reached until the huge SMS message gets wrongly encrypted (probably needs testing). I also guess that mismatching encryption keys between messages is likely the result of perfect forward secrecy and thus "perfectly normal". But in my eyes TextSecure and SMSSecure should show (and possibly prevent any further typing) when the maximum size of a correctly encrypted message is reached. This would prevent the sender thinking that the monster SMS has been delivered, while the receiver only gets "scrambled eggs".