An electronic cam lock on a door, cabinet, panel or drawer in a cabinet or furniture that provides ingress and no egress without a mechanical key, comprising: a compact housing containing electronics and having a terminal enabling entry of a code by a user, such code when properly entered causing the electronics to permit access, the housing being positioned on a panel of said door or other structure of said cabinet or furniture to which the lock is affixed, a lock plug driver extending from a back side of the housing near one end of the housing on a driver rotation axis and engaged with a cam for locking a cabinet or furniture, and including a knob or handle on the housing for operating the lock manually without a mechanical key to rotate the lock driver when permitted by the electronics, a lock actuating mechanism within the housing, including a reciprocal blocking pin engageable with a notch in a rotatable member secured to the knob or handle and the driver, so that the blocking pin is effective to prevent rotation or allow rotation of the handle and the plug driver depending on whether the pin is extended or retracted, a driving mechanism to extend and retract the pin, including a motor with a worm drive gear, an actuator arm having a pivoted end pivotally attached to the housing for rotation about a pivot axis fixed relative to the housing and having a driven end with a worm gear follower engaged with the worm gear so that rotation of the worm gear swings the actuator arm in a first direction of rotation or a second direction of rotation, and the actuator arm being connected via a spring to the blocking pin such that rotation of the actuator arm in the first direction of rotation or the second direction of rotation is effective to move the blocking pin to an extended position or a retracted position but with flexibility for lost motion in extending or retracting the blocking pin when the blocking pin is not aligned with the notch or is binding temporarily in the notch, and a machine screw securing the housing to the door, cabinet, panel or drawer, the machine screw extending into the housing at a position close to the driver rotation axis, in a space bounded at least in part by the motor, the actuator arm and the spring, whereby said one end of the compact housing is retained securely against the door, cabinet, panel or drawer by the machine screw extending into the housing at said space. a compact housing containing electronics and having a terminal enabling entry of a code by a user, such code when properly entered causing the electronics to permit access, the housing being positioned on a panel of said door or other structure of said cabinet or furniture to which the lock is affixed, a lock plug driver extending from a back side of the housing near one end of the housing on a driver rotation axis and engaged with a cam for locking a cabinet or furniture, and including a knob or handle on the housing for operating the lock manually without a mechanical key to rotate the lock driver when permitted by the electronics, a lock actuating mechanism within the housing, including a reciprocal blocking pin engageable with a notch in a rotatable member secured to the knob or handle and the driver, so that the blocking pin is effective to prevent rotation or allow rotation of the handle and the plug driver depending on whether the pin is extended or retracted, a driving mechanism to extend and retract the pin, including a motor with a worm drive gear, an actuator arm having a pivoted end pivotally attached to the housing for rotation about a pivot axis fixed relative to the housing and having a driven end with a worm gear follower engaged with the worm gear so that rotation of the worm gear swings the actuator arm in a first direction of rotation or a second direction of rotation, and the actuator arm being connected via a spring to the blocking pin such that rotation of the actuator arm in the first direction of rotation or the second direction of rotation is effective to move the blocking pin to an extended position or a retracted position but with flexibility for lost motion in extending or retracting the blocking pin when the blocking pin is not aligned with the notch or is binding temporarily in the notch, and a machine screw securing the housing to the door, cabinet, panel or drawer, the machine screw extending into the housing at a position close to the driver rotation axis, in a space bounded at least in part by the motor, the actuator arm and the spring, whereby said one end of the compact housing is retained securely against the door, cabinet, panel or drawer by the machine screw extending into the housing at said space.