Half-cylinder lock

A half-cylinder lock, comprising:

• a lock body, receivable in a lock cavity that is defined in a closure between an external face of the closure and an inner end wall of the lock cavity, the lock body comprises
• a cylinder defining a proximally-distally extending cylinder axis which, once the lock body is within the lock cavity, extends between said external face and said inner end wall,
• a locking piston received within the cylinder and rotatable about the cylinder axis between a locking position and an unlocking position and axially displaceable within the cylinder between a rest position, in which the locking piston is received entirely within the cylinder, a retracted position in which the distal end of the piston proximates the inner end wall and an extended position, in which a proximal end thereof protrudes out of the cylinder permitting rotation of the cylinder by a user between the unlocking and locking positions;
• a biasing member for biasing the piston into the extended position,
• a lock cam, associated with a distal end portion of the locking piston and rotatable therewith between an engaging state, in which the cam is engaged with a cam-engaging element of the lock cavity and an open state, in which the cam is disengaged from the cam-engaging element and the lock can be opened,
• an electrically-driven actuator configured for switching between a blocking state in which it forces a blocking pin into a blocking position to engage the piston so as to arrest it in the rest position and an unblocking state in which the blocking pin is displaced into an unblocking position, in which it does not engage the piston to thereby permit a biased axial displacement of the piston into the extended position;
• and
• an electronic utility, that comprises
• a communication and control module,
• one or more piston detector switch elements in said end wall and in electric communication through a piston detector circuit with said module, said elements being engageable by the piston when in said retracted position to close said circuit,
• the control and communication module being configured for (i) switching from a dormant state to an active state upon closing of the piston detector circuit, (ii) receiving an authenticating signal from a user-held device (iii) upon receipt of such signal activate the electric actuator to switch it into the unblocking state and (iv) upon re-closing of the piston detector circuit, switching said actuator back into the blocking state.