Patent attributes
Methods, systems, and apparatus, including computer programs encoded on computer storage media, for discovery of and communication with nearby devices using direct radio signal communication. One of the methods includes receiving, by a payment service system, a message authorizing a payment from a user account to a merchant account, wherein the message was sent by a user device using direct radio signal communication to a nearby merchant device and forwarded to the payment service system by the merchant device. The message is decrypted to obtain a session token that authenticates the user device as being associated with the user account. If the session token is valid a payment transaction is conducted between the user account and the merchant account.