In some examples, a target device determines that each device of a plurality of devices (i) includes a certificate that is provided to each device during provisioning, (ii) is within a predetermined distance from the target device, (iii) includes a beacon secret that is broadcast to each device at a predetermined time interval, and (iv) that either: (a) a privilege level associated with at least one device of the plurality of devices satisfies a particular privilege level specified by an access policy or (b) a number of the plurality devices with the determined distance from the target device satisfies a predetermined number specified by the access policy. The target device grants at least one device of the plurality of devices access to the target device, and receives a message from the at least one device. The target device initiates an action based at least in part on the message.