ASSA C4/CLIQ Function /Other/assalockCOM/Resources/Videos.jpg The C4/CLIQ-function is a programmable electronic function that does not require any wiring; the power supply comes from the battery in the key. A Master Key System utilizing the C4/CLIQ-function can include many different retrofit cylinder models. The lock cylinder has a built in memory chip and a processor. The key has a similar chip in the key bow. The electronic code in the key collaborates with the electronics and the built-in motor in the lock cylinder. All communication between the key and cylinder is protected by Data Encryption Standard (DES). This provides secure digital communication between the key, cylinder and programming device. A C4/CLIQ-key has the same mechanical codes as an ASSA Maximum Plus key, which consists of both a system code and a side code. The combination of mechanical codes and the electronic codes results in high security and maximum flexibility.