There are plenty of secure messaging services out there. Making one that works for everyone is not a trivial problem. Suppose you own a coffee shop and offer

There are plenty of secure messaging services out there. Making one that works for everyone is not a trivial problem. Suppose you own a coffee shop and offer free wifi, should you be held responsible if someone logs into a bank without SSL and gets their credentials sniffed? Should you be responsible for designing a wifi protocol that uniquely encrypts the traffic of each user, without shared keys, to prevent sniffing?