INFORMATION PROCESSING APPARATUS, VERIFICATION PROCESSING APPARATUS, AND CONTROL METHODS THEREOF

• US 20070058803A1
• Filed: 09/06/2006
• Published: 03/15/2007
• Est. Priority Date: 09/09/2005
• Status: Abandoned Application

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Suga, Yuji
• Application Number:
  US11/470,389
• Publication Number:
  US 20070058803A1
• Time in Patent Office: Days
• US Class Current: 380/30
• CPC Class Codes: H04L 63/0442 wherein the sending and receiving network entities apply asymmetric encryption, i.e. different keys for encryption and decryption cryptographic mechanisms or cryptographic arrangements for public-key encryption H04L9/30
• CPC Class Codes: H04L 63/12 Applying verification of the received information cryptographic mechanisms or cryptographic arrangements for data integrity or data verification H04L9/32
• CPC Class Codes: H04L 63/123 received data contents, e.g. message integrity

Abstract

An information processing apparatus comprising, a first generation unit adapted to generate data to be signed by dividing a digital document into regions, a second generation unit adapted to generate first digest values of the data to be signed and identifiers used to identify the data to be signed, a third generation unit adapted to generate signature information based on a plurality of the first digest values and the identifiers obtained from the digital document, and a fourth generation unit adapted to generate a first signed digital document based on the signature information and the data to be signed.

Claims

1. An information processing apparatus comprising:

a first generation unit adapted to generate data to be signed by dividing a digital document into regions;

a second generation unit adapted to generate first digest values of the data to be signed and identifiers used to identify the data to be signed;

a third generation unit adapted to generate signature information based on a plurality of the first digest values and the identifiers obtained from said digital document; and

a fourth generation unit adapted to generate a first signed digital document based on the signature information and the data to be signed.

2. An information processing apparatus as claimed in claim 1, wherein said third generation unit generates a signature value using the plurality of first digest values and identifiers obtained from said digital document, and an encryption key, and generates the signature information using the generated signature value and the plurality of first digest values and identifiers.

3. An information processing apparatus as claimed in claim 2, further comprising:

a selection acceptance unit adapted to accept selection of the data to be signed,

wherein, said third generation unit generates the signature information based on the first digest value and the identifier of the data to be signed, the selection of which is accepted by said selection acceptance unit.

4. An information processing apparatus as claimed in claim 2, further comprising:

a region designation acceptance unit adapted to accept designation of a predetermined region of the digital document,

wherein said first generation unit generates the data to be signed for the predetermined region designated by said region designation acceptance unit.

5. A verification processing apparatus which verifies a digital document based on a first signed digital document generated by an information processing apparatus according to claim 2, the verification processing apparatus comprising:

an extraction unit adapted to extract the signature information from the first signed digital document;

a determination unit adapted to determine whether the first digest value and the identifier in the signature information have been altered or not;

an obtaining unit adapted to obtain the data to be signed from the first signed digital document based on the identifier when said determination unit determines that the first digest value and the identifier have not been altered;

a calculation unit adapted to calculate a second digest value of the data to be signed;

a comparison unit adapted to compare the first digest value and the second digest value; and

a verification result generation unit adapted to generate a verification result based on the comparison result.

6. A verification processing apparatus as claimed in claim 5, wherein said determination unit determines whether the first digest value and the identifier in the signature information have been altered or not based on whether or not a result obtained by decrypting the signature value included in the signature information using a decryption key matches the first digest value and the identifier.

7. A verification processing apparatus as claimed in claim 5, wherein said obtaining unit obtains the data to be signed even when said obtaining unit cannot obtain data to be signed corresponding to one of the plurality of identifiers but can obtain data to be signed corresponding to other identifiers.

8. A verification processing apparatus as claimed in claim 5, further comprising:

an operation unit adapted to apply an operation to the first signed digital document; and

a fifth generation unit adapted to generate a second signed digital document based on the first signed digital document which has undergone the operation,

wherein, when said operation unit reconstructs a digital document by selecting any of the data to be signed included in the first signed digital document, said fifth generation unit generates the second signed digital document based on the signature information and the data to be signed selected by the operation for the reconstructed digital document.

9. A method for controlling an information processing apparatus, comprising:

a first generation step of generating data to be signed by dividing a digital document into regions;

a second generation step of generating first digest values of the data to be signed and identifiers used to identify the data to be signed;

a third generation step of generating signature information based on a plurality of the first digest values and the identifiers obtained from said digital document; and

a fourth generation step of generating a first signed digital document based on the signature information and the data to be signed.

10. A method for controlling an information processing apparatus as claimed in claim 9, wherein, in the third generation step, a signature value is generated using the plurality of first digest values and identifiers obtained from said digital document, and an encryption key, and the signature information is generated using the generated signature value and the plurality of first digest values and identifiers.

11. A method for controlling an information processing apparatus as claimed in claim 10, further comprising:

a selection acceptance step of accepting selection of the data to be signed,

wherein in the third generation step, the signature information is generated based on the first digest value and the identifier of the data to be signed, the selection of which is accepted in the selection acceptance step.

12. A method for controlling an information processing apparatus as claimed in claim 10, further comprising:

a region designation acceptance step of accepting designation of a predetermined region of the digital document,

wherein, in the first generation step, the data to be signed is generated for the predetermined region designated in the region designation acceptance step.

13. A method for controlling a verification processing apparatus which verifies a digital document based on a first signed digital document generated by a method according to claim 10, the method comprising:

an extraction step of extracting the signature information from the first signed digital document;

a determination step of determining whether the first digest value and the identifier in the signature information have been altered or not;

an obtaining step of obtaining the data to be signed from the signed digital document based on the identifier when it is determined in the determination step that the first digest value and the identifier have not been altered;

a calculation step of calculating a second digest value of the data to be signed;

a comparison step of comparing the first digest value and the second digest value; and

a verification result generation step of generating a verification result based on the comparison result.

14. A method for controlling a verification processing apparatus as claimed in claim 13, wherein, in the determination step, the determination whether the first digest value and the identifier in the signature information have been altered or not is based on whether or not a result obtained by decrypting the signature value included in the signature information using a decryption key matches the first digest value and the identifier.

15. A method for controlling a verification processing apparatus as claimed in claim 13, wherein, in the obtaining step, the data to be signed is obtained even when data to be signed corresponding to one of the plurality of identifiers cannot be obtained but data to be signed corresponding to other identifiers can be obtained.

16. A method for controlling a verification processing apparatus as claimed in claims 13, further comprising:

an operation step of applying an operation to the first signed digital document; and

a fifth generation step of generating a second signed digital document based on the first signed digital document which has undergone the operation,

wherein, in the fifth generation step, when a digital document is reconstructed in the operation step by selecting any of the data to be signed included in the first signed digital document, the second signed digital document is generated based on the signature information and the data to be signed selected by the operation for the reconstructed digital document.

17. A computer program stored in computer readable storage medium, which when loaded into a computer and executed performs a method according to claim 9.