The present invention advantageously provides at least one keyway in a lock core that poses tremendous difficulty for a lock breaker by not allowing the lock breaker to see all of the pin tumblers in the keyway. The keyway according to a preferred embodiment of the present invention comprises two helical keyways oppositely extending along a longitudinal axis of the lock core and formed of rectangular cross section. The present invention further comprises an accompanying helical key having at least one helical key blade for fitting into the keyway having a corresponding helical shape to turn the core and open the lock.