A system, comprising: a key storage medium, comprising a protected area being an area of which a general user cannot read out data directly, a user area being an area of which a general user can read out data directly, and a system area storing a medium identifier (ID m), and an encoding and recording apparatus (40a to 40f) comprising: means adapted to receive, from the exterior, content key information (Kc n) corresponding to encoded content (Enc_c(Ct n, Kc n)) recorded in a content storage medium; a read/write unit adapted to read out the medium identifier (ID m) from the system area; first encoding means (43E-m) adapted to encode fixed information (ID u) using the read out medium identifier, the fixed information being a user identifier input in advance into the encoding and recording apparatus, and write the obtained encoded fixed information (Enc_m(ID u, ID m)) in the protected area of the key storage medium; decoding means (43D-m) adapted to obtain fixed information by decoding the encoded fixed information in the protected area; and second encoding means (43E-k) adapted to encode the content key information (Kc n) on the basis of the fixed information obtained by the decoding means or fixed information newly input, and write the obtained encoded content key information (Enc_k(Kc n, ID u)) in the user data area of the key storage medium. a key storage medium, comprising a protected area being an area of which a general user cannot read out data directly, a user area being an area of which a general user can read out data directly, and a system area storing a medium identifier (ID m), and an encoding and recording apparatus (40a to 40f) comprising: means adapted to receive, from the exterior, content key information (Kc n) corresponding to encoded content (Enc_c(Ct n, Kc n)) recorded in a content storage medium; a read/write unit adapted to read out the medium identifier (ID m) from the system area; first encoding means (43E-m) adapted to encode fixed information (ID u) using the read out medium identifier, the fixed information being a user identifier input in advance into the encoding and recording apparatus, and write the obtained encoded fixed information (Enc_m(ID u, ID m)) in the protected area of the key storage medium; decoding means (43D-m) adapted to obtain fixed information by decoding the encoded fixed information in the protected area; and second encoding means (43E-k) adapted to encode the content key information (Kc n) on the basis of the fixed information obtained by the decoding means or fixed information newly input, and write the obtained encoded content key information (Enc_k(Kc n, ID u)) in the user data area of the key storage medium. means adapted to receive, from the exterior, content key information (Kc n) corresponding to encoded content (Enc_c(Ct n, Kc n)) recorded in a content storage medium; a read/write unit adapted to read out the medium identifier (ID m) from the system area; first encoding means (43E-m) adapted to encode fixed information (ID u) using the read out medium identifier, the fixed information being a user identifier input in advance into the encoding and recording apparatus, and write the obtained encoded fixed information (Enc_m(ID u, ID m)) in the protected area of the key storage medium; decoding means (43D-m) adapted to obtain fixed information by decoding the encoded fixed information in the protected area; and second encoding means (43E-k) adapted to encode the content key information (Kc n) on the basis of the fixed information obtained by the decoding means or fixed information newly input, and write the obtained encoded content key information (Enc_k(Kc n, ID u)) in the user data area of the key storage medium.