A secure locking and unlocking system includes a plug body that is cylindrical in shape, a locking ring and a notched washer. One face of the notched washer is positioned on the locking surface of the locking ring. The system further includes a holding pin that locks the position of a locking element and an upper ring mounted on the locking ring. The locking ring includes a ramp-shaped groove with a linear part, a rising ramp and a descending ramp. A ramp spring is configured so that the locking or unlocking movement of the upper ring is mobile and the locking ring is fixed. The upper ring includes a hole in which a lug is placed. The end of the lug cooperates with the ramp-shaped groove of the locking ring that guides the upper ring in relation to the locking ring.