US Patent 10033712 Network security based on proximity

A processing system periodically configures a beacon code and random nonce to transmit to a beacon device at a location. Multiple users enter the location with associated user computing devices. The user computing devices retransmit the beacon code broadcasted by the beacon device to the processing system. A particular user initiates a transaction at a computing device at the location, which transmits to the processing system a request for account data and retransmits the beacon code and a random nonce. The processing system verifies the beacon code and random nonce and transmits, to the computing device at the location, user account identifiers associated with user computing devices that retransmitted the beacon code. The processing system receives a selection of the user identifier from the merchant point of sale device and transmits account information to the computing device at the location.