Secure locking and unlocking system comprising: - a plug body of cylindrical shape, said plug body comprises on the external wall a threaded portion - a locking ring threaded inside able to be mounted on the plug body, said locking ring comprises at least one orifice, the orifice extends along an axis parallel to the longitudinal axis of the locking ring opening onto a locking surface, said locking ring being configured to lock the locking system in one direction of rotation of the locking ring and to unlock the locking system in the other direction of rotation of the locking ring, - a serrated washer, of which one face is positioned on the locking surface of the locking ring, - a retaining pin for blocking the position of a blocking element inserted into the orifice extending beyond the locking surface, - a upper ring mounted on the locking ring, the upper ring comprises a contact surface able to bear on the other face of the serrated washer, said upper ring comprises a lever suitable for unblocking the blocking element in the direction of rotation of the locking ring, - the blocking element, such as a latch, mounted on the retaining pin blocking the position of the blocking element, said blocking element comprises a flexible portion able to be housed between two notches of the serrated washer, characterised in that: - the locking ring comprises a groove, said groove in the form of a ramp having a linear portion, then an ascending ramp and a descending ramp, - a ramp spring, configured so that the movement of the locking or of the unlocking of the upper ring is mobile and that the locking ring is fixed, the upper ring is mobile in relation to the locking ring, - the upper ring comprises a hole wherein is positioned lug of which the end of the lug engages with the groove in the shape of a ramp of the locking ring guiding the upper ring with respect to the locking ring. - a plug body of cylindrical shape, said plug body comprises on the external wall a threaded portion - a locking ring threaded inside able to be mounted on the plug body, said locking ring comprises at least one orifice, the orifice extends along an axis parallel to the longitudinal axis of the locking ring opening onto a locking surface, said locking ring being configured to lock the locking system in one direction of rotation of the locking ring and to unlock the locking system in the other direction of rotation of the locking ring, - a serrated washer, of which one face is positioned on the locking surface of the locking ring, - a retaining pin for blocking the position of a blocking element inserted into the orifice extending beyond the locking surface, - a upper ring mounted on the locking ring, the upper ring comprises a contact surface able to bear on the other face of the serrated washer, said upper ring comprises a lever suitable for unblocking the blocking element in the direction of rotation of the locking ring, - the blocking element, such as a latch, mounted on the retaining pin blocking the position of the blocking element, said blocking element comprises a flexible portion able to be housed between two notches of the serrated washer, characterised in that: - the locking ring comprises a groove, said groove in the form of a ramp having a linear portion, then an ascending ramp and a descending ramp, - a ramp spring, configured so that the movement of the locking or of the unlocking of the upper ring is mobile and that the locking ring is fixed, the upper ring is mobile in relation to the locking ring, - the upper ring comprises a hole wherein is positioned lug of which the end of the lug engages with the groove in the shape of a ramp of the locking ring guiding the upper ring with respect to the locking ring. - the locking ring comprises a groove, said groove in the form of a ramp having a linear portion, then an ascending ramp and a descending ramp, - a ramp spring, configured so that the movement of the locking or of the unlocking of the upper ring is mobile and that the locking ring is fixed, the upper ring is mobile in relation to the locking ring, - the upper ring comprises a hole wherein is positioned lug of which the end of the lug engages with the groove in the shape of a ramp of the locking ring guiding the upper ring with respect to the locking ring.