The decoder apparatus 90 generates a random number R1 for authenticating the optical disc drive apparatus 70 and sends it to the optical disc drive apparatus 70 as the challenge data CHA1. The optical disc drive apparatus 70 selects one out of the sixteen claimant functions stored in the claimant function unit 722 and calculates the function value fi(CHA1) which it sends to the decoder apparatus 90 as the response data RES1. The decoder apparatus 90 compares the response data RES1 with sixteen function values f1(R1) to f16(R1) that are obtained using the sixteen verification functions stored in the verification function unit 922, and authenticates the optical disc drive apparatus 70 when at least one of the function values matches the response data RES1.