1. A system comprising: one or more processing elements; an object detection module communicatively coupled to or integrated with the one or more processing elements and configured to detect a first object when the first object is in view of a first video camera associated with a first site having a first privacy boundary that encompasses the first video camera; a preprocessing module communicatively coupled to or integrated with the one or more processing elements and configured to perform local processing of at least a portion of the first video to form a first secure input; a circuit generator communicatively coupled to or integrated with the one or more processing elements and configured to generate a function, wherein inputs to the function comprise the first secure input from the first site and a second secure input from a second site having a second privacy boundary that encompasses a second video camera and that does not overlap with the first privacy boundary, wherein the first privacy boundary prevents a user at the first site from obtaining video captured by the second video camera at the second site and the second privacy boundary prevents a user at the second site from obtaining video captured by the first video camera at the first site, the second secure input generated by processing a second object that was in view of the second video camera associated with the second site; a match query module communicatively coupled to or integrated with the one or more processing elements and configured to send a query to the second site to request participation in solving function; and a joint computation module communicatively coupled to or integrated with the one or more processing elements and configured to solve the function with the second site to determine if the first object is the same as the second object.