Patent ID: 7868736

Claim:
A security device for use in a vehicle authenticating device which is mounted on a vehicle capable of running in accordance with engine startup information and which authenticates a user of the vehicle based on an electronic key device having electronic key data (K) stored therein, the security device comprising: key information storage device for storing an encrypted engine master key (E (EK)) obtained by encrypting an engine master key (EK) in accordance with the electronic key data (K); certificate information storage device having an ID device certificate verification key (CK) to verify a certificate (C) in an ID device having a personal information for specifying an individual user, the certificate (C), and a user specific key (I) stored therein; a device for verifying the certificate (C) input from the ID device by using the IC device certificate verification key (CK) in the certificate information storage device to confirm validity of the ID device; a device for, after confirming the validity of the ID device, causing the ID device to verify user inputted authentication information by transmitting the user inputted authentication information to the ID device, the ID device verifying the user inputted authentication information based on the personal information; a signature verification key storage device storing an electronic key data signature verification key (VMK) to verify a digital signature applied to an electronic key data (K); an authentication device for, when a verification result by the ID device has been successfully obtained, authenticating the digital signature of the electronic key data (K) based on the electronic key data signature verification key (VMK), the electronic key data (K) inputting from the electronic key device; a device for, when authentications of the digital signature of the electronic key data (K) have been successfully made, decrypting the encrypted engine master key (E (EK)), and then, obtaining an engine master key (EK), based on the electronic key data (K); a device for producing the engine startup information by using the engine master key (EK); and a device for outputting the obtained engine startup information.