A mechanism is provided to secure integrated circuit devices that combines a high degree of security with a low overhead, both in area and cost, thereby making it appropriate for smaller, cheaper integrated circuits. A determination is made whether a device die is on a wafer or if the device die is incorporated into a package. Only if the device die is incorporated in a package can the functional logic of device die be activated, and then only if a challenge-response query is satisfied. In some embodiments, a random number generator is used during wafer testing to form a pair of numbers, along with a die identifier, that is unique for each device die. A final test is then performed in which the device die can be activated if the device die is incorporated in a package, and the die identifier—random number pair is authenticated.