The invention relates to an electronic key (32) having at least two contacts (324, 325, 326) for the transmission of data and/or energy to an electronic lock (16). In accordance with the invention, the housing (321) of the electronic key (32) comprises an input device (33) for the entry of an authorization code (36). The invention also relates to an electronic closure system with an electronic key (32) and an electronic lock (16) as well as to a method for secure acquisition of an access authorization or for secure delivery of a key to at least one user (22) by means of an electronic lock (16) and at least one electronic key (32) carried by the user (22).