A method comprising: establishing , by a first device associated with a first user, a secure communication channel with a second device associated with a second user via a direct wireless connection; transmitting , by the first device , over the secure communication channel, first device-identifying information to the second device , and receiving , over the secure communication channel, second device-identifying information from the second device ; establishing , by the first device, a particular type of relationship with the second device ; storing, by the first device , the second device-identifying information in association with an indication of the particular type of relationship established with the second device ; transmitting , by the first device , to the second device , and over the secure communication channel, the indication of the particular type of relationship established with the second device ; receiving , by the first device , a message from the second device , wherein the message comprises device-identifying information corresponding to the second device ; verifying , by the first device , that the particular type of relationship was established with the second device based at least in part on a comparison of the device-identifying information included in the message to the second device-identifying information received from the second device over the secure communication channel; and in response to verifying that the particular type of relationship was established with the second device , causing at least a portion of the message to be displayed on the first device . establishing , by a first device associated with a first user, a secure communication channel with a second device associated with a second user via a direct wireless connection; transmitting , by the first device , over the secure communication channel, first device-identifying information to the second device , and receiving , over the secure communication channel, second device-identifying information from the second device ; establishing , by the first device, a particular type of relationship with the second device ; storing, by the first device , the second device-identifying information in association with an indication of the particular type of relationship established with the second device ; transmitting , by the first device , to the second device , and over the secure communication channel, the indication of the particular type of relationship established with the second device ; receiving , by the first device , a message from the second device , wherein the message comprises device-identifying information corresponding to the second device ; verifying , by the first device , that the particular type of relationship was established with the second device based at least in part on a comparison of the device-identifying information included in the message to the second device-identifying information received from the second device over the secure communication channel; and in response to verifying that the particular type of relationship was established with the second device , causing at least a portion of the message to be displayed on the first device . <EOS>