Signal recording and reproduction and signal record media

A signal reproducing apparatus, in which unauthorized decoding or copying is rendered difficult, reproduces enciphered data from a disk-shaped record medium (101) on which are recorded data enciphered by at least one encryption operation and key storage site information specifying an arraying site for at least one key information item used for deciphering the enciphered data. The apparatus includes a reproducing head device (212) for reading the enciphered data and the key storage site information from the record medium (101), a TOC decoder (219), a CPU (224) and a digital signal processing circuit (220) for decoding the enciphered data using the key information stored on the site designated in accordance with the key storage site information.