Door lock comprising: - a lock cylinder comprising: - a fixed stator, - a rotor mounted so as to rotate in the stator, this rotor having a key channel, one inlet of which is intended to open out on an external side of the door, this rotor being able to be displaced, in rotation about a rotation spindle integral with the stator, by a key authorised to unlock the cylinder and introduced into the key channel, - an anti-drilling disc comprising a slot through which the authorised key can pass, this anti-drilling disc being located in front of the key channel entrance and mounted so that it can rotate freely about the rotor's axis of rotation, - a device for detecting an attempted break-in capable of detecting an attempted break-in by drilling the cylinder rotor, characterised in that the device for detecting an attempted break-in comprises: - a unit for measuring the rotation of the anti-drilling disc, and - a module for detecting an attempted break-in configured to: - acquire the measurements from the measurement unit and deduce therefrom a speed of rotation of the anti-drilling pad, - establish the existence of an attempted break-in by comparing the speed of rotation of the anti-drilling pad deduced with a predetermined maximum threshold, and - automatically triggering the signalling of an attempted break-in as soon as the existence of an attempted break-in is established from the speed of rotation of the anti-drilling pad deduced and, otherwise, not triggering this signalling of an attempted break-in. - a lock cylinder comprising: - a fixed stator, - a rotor mounted so as to rotate in the stator, this rotor having a key channel, one inlet of which is intended to open out on an external side of the door, this rotor being able to be displaced, in rotation about a rotation spindle integral with the stator, by a key authorised to unlock the cylinder and introduced into the key channel, - a fixed stator, - a rotor mounted so as to rotate in the stator, this rotor having a key channel, one inlet of which is intended to open out on an external side of the door, this rotor being able to be displaced, in rotation about a rotation spindle integral with the stator, by a key authorised to unlock the cylinder and introduced into the key channel, - an anti-drilling disc comprising a slot through which the authorised key can pass, this anti-drilling disc being located in front of the key channel entrance and mounted so that it can rotate freely about the rotor's axis of rotation, - a device for detecting an attempted break-in capable of detecting an attempted break-in by drilling the cylinder rotor, - a unit for measuring the rotation of the anti-drilling disc, and - a module for detecting an attempted break-in configured to: - acquire the measurements from the measurement unit and deduce therefrom a speed of rotation of the anti-drilling pad, - establish the existence of an attempted break-in by comparing the speed of rotation of the anti-drilling pad deduced with a predetermined maximum threshold, and - automatically triggering the signalling of an attempted break-in as soon as the existence of an attempted break-in is established from the speed of rotation of the anti-drilling pad deduced and, otherwise, not triggering this signalling of an attempted break-in. - acquire the measurements from the measurement unit and deduce therefrom a speed of rotation of the anti-drilling pad, - establish the existence of an attempted break-in by comparing the speed of rotation of the anti-drilling pad deduced with a predetermined maximum threshold, and - automatically triggering the signalling of an attempted break-in as soon as the existence of an attempted break-in is established from the speed of rotation of the anti-drilling pad deduced and, otherwise, not triggering this signalling of an attempted break-in.