2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/93958We review the main protocols for key distribution based on principles of quantum mechanics, describing the general underlying ideas, discussing implementation requirements and pointing out directions of current experiments. The issue of security is addressed both from a principal and real-life point of view.12 pages, final version, accepted for publication in AAECCQuantum Physicstext