The invention relates to a lock-key system, including a key that is insertable into a key channel of a lock cylinder, and traceable by core pins or by locking elements that are displaceable in the cylinder core, wherein in case of a match, the cylinder core can be rotated by means of the inserted key. Lettering in the form of an impression and/or an embossment, serving as an identifier and including letters and/or numbers and/or symbols, is introduced into at least one lateral surface of the key shank and in case of a lateral profiling, into the lateral profiling. The lettering or individual letters, numbers, or the symbol or sub-areas thereof are traceable by core pins or locking elements having a correspondingly formed contact surface.

A lock comprises: a body with a housing comprising a first and a second portion mutually adjacent along an longitudinal development direction corresponding to an insertion direction of a key; a first rotor with a further housing, rotationally housed within the first portion of the housing of the body; a second rotor comprising a first portion rotationally housed within the second portion of the housing of the body; a second portion rotationally housed within the further housing of the first rotor. The second rotor, inserting the key, translates along the longitudinal development direction of the body with respect to the first rotor and, by a first rotation portion of the key, rotates with respect to the first rotor, passing from disengaging to engaging the first rotor, wherein the first rotor and the second rotor, by a second portion of rotation of the key, integrally translate to actuate the lock.