One embodiment of a method of operating a first user device to exchange images between the first user device and a second user device, the method comprising: detecting, by the first user device, a proximity gesture between the first user device and the second user device; responsive to the proximity gesture: transmitting, from the first user device to the second user device, a first digest including location history associated with the first user device; receiving, at the first user device, a second digest including location history associated with the second user device transmitted from the second user device; identifying, by the first user device using the second digest, one or more images captured by the first user device based on the second digest; and transmitting, from the first user device to the second user device, the one or more images.