It is a source of security digital characters, incomprehensible to the naked eye, which can only be identified when the transparent substrate (acrylic, plastic or another material) is placed over the substrate on which they were printed (paper, PVC, polyester, film or others), or over the screen where they are displayed (CRT, LCD, plasma, acrylic or others), and the characters that are unreadable characters may be embedded or may be part of photos, images, drawings, illustrations, logos or figures, and the transparent base contains the remaining and complementary parts of the characters already printed or displayed on the screen, in a manner that their combination with the characters printed or displayed on the screen reveals them or make them comprehensible and identifiable, being that each substrate, described thus, may reveal or make comprehensible a series of documents containing these sources printed or displayed on the screen, or may even reveal and make the characters printed or displayed on the screen comprehensible from a single document containing these sources, in a manner that these characters make up a single-valued and reciprocal match with the transparent substrate, and in the latter case, both the printed characters or characters displayed on the screen, and the transparent substrate are created exclusively for one another.