Abstract: A method and apparatus for reading a key, preferably a key of the type having indentations formed in the flat sides of the key blade. Typical uses for such method and apparatus include incorporating the same in a machine for making a lock to be opened by that key or incorporation in a door lock to identify a given key and by this means a given holder of the key. Movement of reading pins which sense the key indentations are multiplied to cover or uncover groups of juxtaposed light paths to electronically record the depth of the key indentations. Plural indentations on a key can be read either sequentially or simultaneously in parallel.