A method of verifying a connection between at least two user profiles by a handshake, each user profile being associated with a mobile device, and each mobile device having at least means for connecting to a data network and means for short-range direct connectionless and unaddressed broadcast communication with the other device(s), for example a Bluetooth Low Energy radio, the method comprising the steps of: a first device receiving an input to initiate a handshake, and in response to the input, broadcasting by the short-range direct connectionless and unaddressed broadcast communication means of the first device a broadcast including at least an indication that a handshake has been initiated; and an identifier for a first user profile associated with the first device, a second device broadcasting by the short-range direct connectionless and unaddressed broadcast communication means of the second device a broadcast including at least an indication that a handshake has been initiated; and an identifier for a second user profile associated with the second device, the first device receiving the broadcast from the second device and the second device receiving the broadcast from the first device, and each device in response to receiving the relevant broadcast, outputting to a user associated with its respective user profile: an indication that the broadcast has been received; and information about the user profile associated with the other device, and each device in response to receiving an input of user confirmation that a handshake is to be completed: sending to an external server via the data network a record of a completed handshake, including at least the identifier associated with the first user profile and the identifier associated with the second user profile, and by the external server, matching a record received from the first device with a record received from the second device, and on matching being achieved, determining that a connection between the first user profile and the second user profile has been verified. a first device receiving an input to initiate a handshake, and in response to the input, broadcasting by the short-range direct connectionless and unaddressed broadcast communication means of the first device a broadcast including at least an indication that a handshake has been initiated; and an identifier for a first user profile associated with the first device, an indication that a handshake has been initiated; and an identifier for a first user profile associated with the first device, a second device broadcasting by the short-range direct connectionless and unaddressed broadcast communication means of the second device a broadcast including at least an indication that a handshake has been initiated; and an identifier for a second user profile associated with the second device, an indication that a handshake has been initiated; and an identifier for a second user profile associated with the second device, the first device receiving the broadcast from the second device and the second device receiving the broadcast from the first device, and each device in response to receiving the relevant broadcast, outputting to a user associated with its respective user profile: an indication that the broadcast has been received; and information about the user profile associated with the other device, an indication that the broadcast has been received; and information about the user profile associated with the other device, and each device in response to receiving an input of user confirmation that a handshake is to be completed: sending to an external server via the data network a record of a completed handshake, including at least the identifier associated with the first user profile and the identifier associated with the second user profile, and by the external server, matching a record received from the first device with a record received from the second device, and on matching being achieved, determining that a connection between the first user profile and the second user profile has been verified.