The invention relates to a secured device for locking and unlocking a plug on a frame with a wrench. The device has an obstructing component that is mobile with respect to a plug and can be brought from an obstructing position to an unobstructing position in which the wrench can engage a rotor of a bolt when an identification code of the wrench, read by a reader, is in agreement with the code stored in an electronic module that is associated with the plug.