Authentication apparatus, authentication target apparatus, image forming apparatus, replacement unit, and authentication method

An authentication method for authenticating an authentication target apparatus that is mounted in a cartridge detachably attachable to an image forming apparatus including an authentication apparatus, and that is authenticated by the authentication apparatus, the authentication method comprising:

• the authentication apparatus generating verification data by using a verification key and challenge data;
• the authentication apparatus generating first encrypted data by encrypting first data including at least the challenge data in accordance with first encryption processing information, and transmitting the first encrypted data to the authentication target apparatus;
• the authentication target apparatus acquiring the challenge data by decrypting the first encrypted data received from the authentication apparatus in accordance with second encryption processing information;
• the authentication target apparatus generating authentication data by using the challenge data acquired by the decryption and an authentication key stored in advance in the authentication target apparatus;
• the authentication target apparatus generating second encrypted data by encrypting second data including at least the authentication data in accordance with the second encryption processing information, and transmitting the second encrypted data to the authentication apparatus;
• the authentication apparatus acquiring the authentication data by decrypting the second encrypted data received from the authentication target apparatus in accordance with the first encryption processing information;
• and
• the authentication apparatus authenticating the authentication target apparatus by comparing the authentication data acquired by the decryption with the verification data,
• wherein the authentication apparatus changes the first encryption processing information in accordance with a predetermined rule when the encryption of the first data is performed, and
• wherein the authentication target apparatus changes the second encryption processing information in accordance with the predetermined rule when the encryption of the second data is performed.

An authentication target apparatus that is mounted in a cartridge detachably attachable to an image forming apparatus including an authentication apparatus, and that is authenticated by the authentication apparatus, the authentication target apparatus comprising:

• a storage unit configured to store an authentication key;
• a first generation unit configured to generate encryption processing information;
• a decryption unit configured to decrypt, in accordance with the encryption processing information generated by the first generation unit, first encrypted data that is received from the authentication apparatus and that is generated by encrypting data including at least challenge data;
• a generation unit configured to generate authentication data based on the authentication key stored in the storage unit and the challenge data acquired by the decryption;
• and
• an encryption unit configured to generate second encrypted data by encrypting data including the authentication data in accordance with the encryption processing information generated by the first generation unit, and to transmit the second encrypted data to the authentication apparatus,
• wherein the first generation unit is configured to change the encryption processing information in accordance with a predetermined rule when either decryption processing by the decryption unit or encryption processing by the encryption unit is performed.

An authentication apparatus provided in an image forming apparatus and configured to authenticate an authentication target apparatus mounted in a cartridge detachably attachable to the image forming apparatus, the authentication apparatus comprising:

• a storage unit configured to store a verification key;
• a first generation unit configured to generate encryption processing information;
• a second generation unit configured to generate challenge data;
• an encryption unit configured to generate first encrypted data by encrypting first data including at least the challenge data in accordance with the encryption processing information generated by the first generation unit, and to transmit the first encrypted data to the authentication target apparatus;
• a decryption unit configured to receive second encrypted data from the authentication target apparatus in response to transmission of the first encrypted data to the authentication target apparatus, and to acquire authentication data by decrypting the second encrypted data in accordance with the encryption processing information generated by the first generation unit;
• a third generation unit configured to generate verification data based on the verification key stored in the storage unit and the challenge data;
• and
• an authentication unit configured to authenticate the authentication target apparatus by comparing the authentication data acquired by the decryption unit with the verification data,
• wherein the first generation unit is configured to change the encryption processing information in accordance with a predetermined rule when either encryption processing by the encryption unit or decryption processing by the decryption unit is performed.