A lock assembly includes a plug with a keyway, primary pins aligned with the keyway for controlling rotation of the plug, a sidebar for controlling rotation of the plug, secondary pins adjacent the keyway for controlling movement of the sidebar, and at least one supplemental sidebar control element for controlling movement of the sidebar. The lock assembly is operated by simultaneously manipulating the primary pins, the secondary pins, and the supplemental sidebar control element to place each in a respective position and/or orientation to permit rotation of the plug and to permit sufficient movement of the sidebar to permit rotation of the plug and then applying torque to the plug.