Abstract: A safety system comprising closure means, hereinafter termed locks, and associated closure release means, hereinafter termed keys, which operate electronically and which grant access. The lock release is dependent on the agreement or coincidence of a variable lock/key code pair. Random codes are employed which are altered either automatically each time a lock is actuated or only as required. A plurality of locks can be actuated by a common key which possesses another variable code for each lock. In addition, a plurality of keys can actuate a common lock which possesses another variable code for every key. Both possibilities can be combined, since every key and every lock possesses another associated code pair whose association is automatically produced when a lock is actuated. By means of a central key which is safeguarded in the same manner, the user can produce and vary any desired lock/key association so as to eliminate misuse.