By Radu Marinas VASLUI, Romania (Reuters) - Valentin Boanta, sitting in his jail cell, proudly explains the device he has invented which, he says, could make the world's ATMs impregnable even to tech-savvy criminals like himself. Boanta, 33, is six months into a five-year sentence for supplying gadgets an organized crime gang used to conceal ATM skimmers, which can copy data from an unsuspecting ATM user's card so a clone can be created. He said he had started to make the devices for the sheer excitement of it and denies ever planning to use them himself, saying he only sold them to others. ...