We're building a Wifi enabled device. The device will be installed locally on each client's office and people in the the small office will connect to this Wifi enabled device, They will send/receive sensitive data. As we cannot use signed/trusted certificate per client, how can we guarantee that two users who are connected to same WAN cannot sniff on each other?
What type of encryption should our mobile app and our server app should implement? Challenge-response? RSA? What algorithm and how? What do you think? We need high grade encryption and impossible to sniff connection between each individual and central server.