A lock and a key are provided wherein the key is used in conjunction with the lock. The key has a stop bit and a series of coding bits along its shank. The stop bit and each coding bit have a leading edge and a trailing edge to provide coding of the key and to form one side of a groove. The lock has a housing having a key-actuated cogwheel assembly. The cogwheels are registered with a keyhole and are spaced for engagement by the coding bits of the key. A driven cogwheel assembly has a series of cogwheels that mesh with a corresponding key-actuated cogwheel. A lock bolt is projected and retracted between two positions by a lock bolt actuating mechanism responding to position of the stop bit and coding bits.