Data processing device, encryption communication method, key generation method, and computer program

• US 20050228986A1
• Filed: 04/08/2005
• Published: 10/13/2005
• Est. Priority Date: 04/12/2004
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Fukasawa, Nobuaki, Yamauchi, Hisayuki
• Granted Patent: US 8,015,393 B2
• Time in Patent Office: Days
• US Class Current: 713/156
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying
• CPC Class Codes: H04L 9/3263 involving certificates, e.g. public key certificate [PKC] or attribute certificate [AC]; Public key infrastructure [PKI] arrangements network architectures or network communication protocols for supporting authentication of entities using certificates in a packet data network H04L63/0823

Abstract

A data processing device comprises a storage unit adapted to store an initial value of a pair of a public key and a private key and a communication unit adapted to execute communication with an external device with use of the initial value of the pair of the public key and the private key stored in the storage unit, thereby enabling encryption communication without generating the pair of the public key and the private key.

Claims

1. A data processing device comprising:

a storage unit adapted to store an initial value of a pair of a public key and a private key; and

a communication unit adapted to execute encryption communication with an external device by using the initial value of the pair of the public key and the private key stored in said storage unit, without generating the pair of the public key and the private key,

wherein said communication unit receives a new pair of the public key and the private key from the external device through the encryption communication.

2. A data processing device according to claim 1, further comprising:

a validity judgment unit adapted to judge validity of a password or a digest authentication transmitted from the external device; and

an installation permission unit adapted to permit installation of the pair of the public key and the private key by a user to which administrator authority is acknowledged, on the basis of a judgment result by said validity judgment unit,

wherein it enables to install the pair of the public key and the private key from the external device by executing the encryption communication with use of the initial value of the pair of the public key and the private key stored in said storage unit.

3. A data processing device according to claim 1, further comprising a key generation unit adapted to generate the pair of the public key and the private key in said data processing device, in response to an instruction from a user,

wherein it enables to install the pair of the public key and the private key from the external device by executing the encryption communication with use of the pair of the public key and the private key generated by said key generation unit.

4. A data processing device according to claim 1, further comprising a display control unit adapted to cause a display unit to display the initial value of the pair of the public key and the private key stored in said storage unit.

5. A data processing device according to claim 3, further comprising a display control unit adapted to cause a display unit to display a value of the public key generated by said key generation unit.

6. A data processing device according to claim 2, further comprising a display control unit adapted to cause a display unit to display a value of the public key installed from the external device.

7. A data processing device according to claim 1, further comprising a default unit adapted to return the value of the pair of the public key and the private key stored in said storage unit to the initial value, in response to an instruction from a user.

8. A data processing device according to claim 1, further comprising:

a public key transmission unit adapted to transmit the public key stored in said storage unit to the external device;

a first key reception unit adapted to receive the key encrypted by using the public key transmitted by said public key transmission unit;

a second key reception unit adapted to receive a pair of the public key and the private key encrypted; and

a decryption unit adapted to decrypt the pair of the public key and the private key encrypted received by said second key reception unit, by using the key received by said first key reception unit.

9. A data processing device comprising:

a storage unit adapted to store an initial value of a public key certificate; and

a communication unit adapted to execute encryption communication with an external device by using the initial value of the public key certificate stored in said storage unit, without generating the public key certificate,

wherein said communication unit receives a new public key certificate from the external device through the encryption communication.

10. An encryption communication method in which a data processing device is used, comprising:

a communication step of executing encryption communication with an external device by, without generating a pair of a public key and a private key or a public key certificate, using an initial value of the pair of the public key and the private key or of the public key certificate stored in a storage unit,

wherein, in said communication step, a new pair of the public key and the private key or a new public key certificate is transferred from the external device to the data processing device through the encryption communication.

11. A computer program which causes a computer to execute an encryption communication method in which a data processing device is used, said method comprising:

a communication step of executing encryption communication with an external device by, without generating a pair of a public key and a private key or a public key certificate, using an initial value of the pair of the public key and the private key or of the public key certificate stored in a storage unit,

wherein, in said communication step, a new pair of the public key and the private key or a new public key certificate is transferred from the external device to the data processing device through the encryption communication.

12. A data processing device comprising:

a judgment unit adapted to judge whether or not it is necessary to generate a pair of a public key and a private key for executing encryption communication with an external device, in accordance with a start of the operation of said data processing device;

a key generation unit adapted to automatically generate the pair of the public key and the private key in a case where said judgment unit judges that it is necessary to generate the pair of the public key and the private key; and

a key storage unit adapted to store in a storage medium the pair of the public key and the private key generated by said key generation unit.

13. A data processing device according to claim 12, wherein

said judgment unit judges, when said data processing device starts the operation, whether or not the pair of the public key and the private key is stored in the storage medium, and

in a case where it is judged by said judgment unit that the pair of the public key and the private key is not stored in the storage medium, said key generation unit automatically generates the pair of the public key and the private key.

16. A data processing device according to claim 12, further comprising:

a password key generation unit adapted to generate a pseudorandom number from a parameter value inherent to said data processing device, and generate a password key of a common key encryption system on the basis of the generated pseudorandom number;

a password key storage unit adapted to store in a storage medium the password key generated by said password key generation unit;

an encryption unit adapted to encrypt the private key included in the pair of the public key and the private key generated by said key generation unit, by using the password key stored in the storage medium by said password key storage unit; and

a private key decryption unit adapted to decrypt the private key encrypted by said encryption unit, by using the password key stored in the storage medium by said password key storage unit.

17. A data processing device according to claim 12, wherein said judgment unit judges, when said data processing device starts the operation, whether or not a setting value set by the user for generating the pair of the public key and the private key is valid, said key generation unit automatically generates the pair of the public key and the private key when it is judged by said judgment unit that the setting value set by the user is valid, and said key storage unit updates the pair of the public key and the private key stored in a storage medium into the pair of the public key and the private key generated by said key generation unit.

14. A data processing device comprising:

a judgment unit adapted to judge whether or not a pair of a public key and a private key stored in a storage medium is damaged;

a key generation unit adapted to automatically generate the pair of the public key and the private key in a case where said judgment unit judges that the pair of the public key and the private key is damaged; and

a key storage unit adapted to store in the storage medium the pair of the public key and the private key generated by said key generation unit.

15. A data processing device according to claim 14, further comprising:

a first hash value generation unit adapted to generate a one-way hash value of the pair of the public key and the private key generated by said key generation unit;

a hash value storage unit adapted to store in the storage medium the one-way hash value generated by said first hash value generation unit; and

a second hash value generation unit adapted to read the pair of the public key and the private key stored in the storage medium, and generate a one-way hash value of the read pair of the public key and the private key,

wherein said judgment unit compares the one-way hash value generated by said first hash value generation unit with the one-way hash value generated by said second hash value generation unit, and judges based on a result of the comparison whether or not the pair of the public key and the private key stored in the storage medium is damaged.

18. A key generation method comprising:

a judgment step of judging whether or not it is necessary to generate a pair of a public key and a private key for executing encryption communication with an external device, in accordance with a start of an operation of a data processing device;

a key generation step of automatically generating the pair of the public key and the private key in a case where said judgment step judges that it is necessary to generate the pair of the public key and the private key; and

a key storage step of storing in a storage medium the pair of the public key and the private key generated in said key generation step.

19. A computer program which causes a computer to execute:

a judgment step of judging whether or not it is necessary to generate a pair of a public key and a private key for executing encryption communication with an external device, in accordance with a start of an operation of a data processing device;

a key generation step of automatically generating the pair of the public key and the private key in a case where said judgment step judges that it is necessary to generate the pair of the public key and the private key; and

a key storage step of storing in a storage medium the pair of the public key and the private key generated in said key generation step.