The present invention relates to an electronic anti-theft device for computers and other processor-assisted electronics, such as memory components, hard disks, plug-in boards and processors. The anti-theft device comprises a blocking circuit which is integrated with the component to be protected, said circuit comprising a memory for storing a specific identity code (ID-code) for each blocking circuit. In addition, the circuit comprises an input for inputting a key code into the circuit, and a comparator for comparing the introduced key code with the ID-code of the circuit, the circuit being adapted to block the component from further use in case of an incorrect key code.