System for protecting digital equipment against remote access.

System for protection against remote access to digital equipment (1) emitting stray electromagnetic radiation (2) and operating with digital signals under clock control and being based on the representation of a given set of characters, comprising means (18, 19) for emitting protective electromagnetic radiation covering the frequency spectrum of said stray radiation. A store (14) for a character set comprises at least some of the characters in said given set of characters, and means (13) are included for selecting characters in random order from the store (14). The selected characters are applied to drive means (15, 16, 18) which are adapted to generate digital signals corresponding to the selected characters and modulated in a manner corresponding to the digital signals of the equipment (1) so as to be of substantially the same nature as these. Drive means (15, 16, 18) are adapted to emit, preferably continuously, the generated digital signals to an antenna (19) for radiating corresponding protective electromagnetic radiation.