Patent ID: 7228419

Claim:
An information processing apparatus comprising: validity-data generating means for generating validity data including secret information to which an algorithm whose presence is verifiable without being exposed is applicable, said validity data being used for verifying the validity of information; verifying-parameter generating means for generating a verifying parameter for verifying the presence of the secret information; information-to-be-validated generating means for generating information to be validated which includes the verifying parameter and which is validated by the validity data; and output means for outputting a set of information consisting of the validity data and the information to be validated, wherein the set of information forms an electronic ticket, wherein said output means encrypts the validity data and then outputs the encrypted validity data, and wherein said output means sends a device certificate to an external device, said device certificate including a public key used in a public key cryptosystem, and a digital signature generated by a predetermined certifying center for the public key so as to certify that said information processing apparatus is a legal device, and said output means decrypts, by using a secret key corresponding to the public key, an encryption key which is encrypted with the public key contained in the device certificate and which is sent from said external device, and encrypts the validity data with the decrypted encryption key.