A cylinder lock , comprising - a housing and a core rotatable mounted therein; - the core has a longitudinal channel for a key insertion, - coaxial bores and are formed on one side of the key channel , in the core and in the housing respectively, wherein there are axially disposed basic core pins and housing pins loaded by springs ; - additional blocking elements are mounted in the core ; - the additional blocking elements are able to cooperate with a movable cylindrical element mounted on the key , wherein - a pushing element , which is one of the additional blocking elements , is stationary mounted and part of the pushing element is able to correspond to the location of the movable cylindrical element on the key , and wherein a locking element , which is one of the additional blocking elements , is mounted with possibility for rotation around an axis passing through the locking element , and having its one end engaged under a spring pressure into respective slot formed in the housing , characterized in that symmetrically to the central plane, on the outer surface of the core , there are formed first and second longitudinal core slots which are opened into the key channel whereat the pushing element is mounted in the first or in the second core slot by a pin through a bore , made on the outer surface of the core , and the part of the pushing element being able to correspond to the location of the movable cylindrical element on the key is protruded into the key channel and is able to correspond to the location of the additional longitudinal guide groove on the key where the movable cylindrical element is inserted, whereat opposite to the pushing element but on the other side of the key channel in the second core slot or in the first core slot there is mounted the locking element . - a housing and a core rotatable mounted therein; - the core has a longitudinal channel for a key insertion, - coaxial bores and are formed on one side of the key channel , in the core and in the housing respectively, wherein there are axially disposed basic core pins and housing pins loaded by springs ; - additional blocking elements are mounted in the core ; - the additional blocking elements are able to cooperate with a movable cylindrical element mounted on the key , wherein - a pushing element , which is one of the additional blocking elements , is stationary mounted and part of the pushing element is able to correspond to the location of the movable cylindrical element on the key , and wherein a locking element , which is one of the additional blocking elements , is mounted with possibility for rotation around an axis passing through the locking element , and having its one end engaged under a spring pressure into respective slot formed in the housing , characterized in that symmetrically to the central plane, on the outer surface of the core , there are formed first and second longitudinal core slots which are opened into the key channel whereat the pushing element is mounted in the first or in the second core slot by a pin through a bore , made on the outer surface of the core , and the part of the pushing element being able to correspond to the location of the movable cylindrical element on the key is protruded into the key channel and is able to correspond to the location of the additional longitudinal guide groove on the key where the movable cylindrical element is inserted, whereat opposite to the pushing element but on the other side of the key channel in the second core slot or in the first core slot there is mounted the locking element . <EOS>