A plug assembly including a plug, a sidebar movably mounted on the plug, and a plurality rack pins seated in the plug. The sidebar is biased to an outer position in which the sidebar extends beyond an outer surface, of the plug. Each rack pin is a single-piece unitary structure including a key-following leg and a sidebar-engaging leg. The sidebar engaging leg includes at least one true, gate and a plurality of false gates. When a true gate of each rack pin is aligned with the sidebar, the sidebar is free to move radially inward to an inner position.

A key for use in a cylinder lock with a rotatable key plug having a profiled keyway. The key comprises an elongated, substantially flay key blade (120; 120) having a longitudinal profile groove (122; 122) extending along at least a portion of the length of the key blade. The groove has an undercut portion (129) adjacent to a ridge portion (128, 128), the outside of which forms part of a side surface (123; 123) of the key blade. The undercut portion (129; 129) of the groove is expanded, at its innermost part adjacent to and inside said ridge portion, into a longitudinally extending pocket (135; 135).

A bridge tumbler lock has tumblers that both slide and pivot, with their motion controlled by pairs of key interfaces. A sidebar is released to permit lock opening movement when all tumblers are in their correct positions. This results in a lock that is resistant to release of information due to partially correct key combinations occurring in the course of a lock picking attempt and thus enables enhanced security in an economical, effective lock construction.

The disclosure relates to a cylinder lock wherein an eccentric barrel pin assembly with two contact points within the keyway are independently movable within the barrel to a common shear line against a single nested column pin assembly.