Signing method and apparatus using the same

• US 6,072,874 A
• Filed: 12/30/1996
• Issued: 06/06/2000
• Est. Priority Date: 01/26/1996
• Status: Expired due to Term

• Current Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Original Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Inventors: Kobayashi, Kenichi, Aratani, Toru, Shin, Kil-Ho
• Primary Examiner(s): Hayes, Gail O.
• Assistant Examiner(s): SONG, HOSUK
• Application Number:
  US08/777,047
• Time in Patent Office: 1,254 Days
• Field of Search: 380/4, 380/23, 380/25, 380/231, 380/232, 380/229, 380/278
• US Class Current: 380/231
• CPC Class Codes: H04L 9/3247 involving digital signatures

Abstract

The present invention provides a signing apparatus used for signing by a user on usage information of a source provided in a format made available by the use of key information. The apparatus includes a unit for generating the usage information which is to be signed, a unit for performing a first computation by utilizing the key information which has been encrypted and the usage information, a unit for performing a second computation by utilizing a user'"'"'s private key and a result of the first computation. The apparatus further includes a unit for performing a third computation by utilizing a result of the second computation, and thereby generating the key information which has been decrypted and a result of the computation performed on the usage information by utilizing the user'"'"'s private key. The apparatus further includes a unit for making the source available by utilizing the decrypted key information.

Claims

1. A signing apparatus used for signing by a user on usage information of a source provided in a format made to be available by the use of key information, comprising:

means for generating said usage information which is to be signed;

means for performing a first computation by utilizing said key information which has been encrypted and said usage information;

means for performing a second computation by utilizing a private key of said user and a result of said first computation;

means for performing a third computation by utilizing a result of said second computation, and thereby generating said key information which has been decrypted and a result of said computation performed on said usage information by utilizing said private key of said user; and

means for making said source available by utilizing said decrypted key information, wherein said means for performing the first computation assumes the product of two large prime numbers to be a modulus, the two large prime numbers not being known to said user and, using said modulus, generates a first diagonal matrix having said encrypted key information and said usage information as components, and produces a second matrix from said first matrix, said second matrix being a different representation of said first matrix using an arbitrary basis.

3. The signing apparatus according to claim 1, further comprising:

means for storing said result of said third computation performed on said usage information by utilizing said private key of said user.

5. The signing apparatus according to claim 1, wherein a plurality of key information is provided for a single source, and a content of said usage information paired with key information is a fact that said key information decrypted immediately before is used, and the use of said source is closed when said user refuses to sign said usage information.

11. The signing apparatus according to claim 1, further comprising:

means for storing said private key of said user.

12. The signing apparatus according to claim 11, further comprising:

a guarding device for guarding inside information from external access.

2. A signing apparatus used for signing by a user on usage information of a source provided in a format made to be available by the use of key information, comprising:

a guarding device for guarding inside information from external access;

means for generating said usage information which is to be signed;

means disposed in said guarding device for performing a first computation by utilizing said key information which has been encrypted and said usage information;

means for performing a second computation by utilizing a private key of said user and a result of said first computation;

means disposed in said guarding device for performing a third computation by utilizing a result of said second computation, and thereby generating said key information which has been decrypted and a result of said computation performed on said usage information by utilizing said private key of said user; and

means disposed in said guarding device for making said source available by utilizing said decrypted key information, wherein said means for performing the first computation assumes the product of two large prime numbers to be a modulus, the two large prime numbers not being known to said user and, using said modulus, generates a first diagonal matrix having said encrypted key information and said usage information as components, and produces a second matrix from said first matrix, said second matrix being a different representation of said first matrix using an arbitrary basis.

4. The signing apparatus according to claim 2, further comprising:

means disposed in said guarding device for decrypting information which has been encrypted by a key unavailable for said user, wherein said encrypted key information is further encrypted by said key unavailable for the user and provided to said means for decrypting, and said first computation is performed on said key information decrypted by said means for decrypting.

6. An information processing apparatus having a source providing system and a source using system, comprising:

means disposed in said source providing system for protecting and outputting a source;

means disposed in said source providing system for encrypting and outputting key information which cancels said protection;

a guarding device disposed in said source using system for guarding inside information for external access;

means disposed in said source using system for generating usage information which is to be signed;

means disposed in said guarding device for performing a first computation by utilizing said encrypted key information and said usage information;

means disposed in said source using system for performing a second computation utilizing a private key of a user and a result of said first computation; and

means disposed in said guarding device for performing a third computation by utilizing a result of said second computation, and thereby generating said key information which has been encrypted and a result of said computation performed on said usage information by utilizing said private key of said user; and

means disposed in said guarding device for making said source available by utilizing said key information, wherein said means for performing the first computation assumes the product of two large prime numbers to be a modulus, the two large prime numbers not being known to said user and, using said modulus, generates a first diagonal matrix having said encrypted key information and said usage information as components, and produces a second matrix from said first matrix, said second matrix being a different representation of said first matrix using an arbitrary basis.

7. A signing method used for signing by a user on usage information of a source provided in a format made to be available b the use of key information, comprising the steps of:

generating said usage information which is to be signed;

performing a first computation by utilizing said key information which is encrypted and said usage information;

performing a second computation by utilizing a result of said first computation and a private key of said user;

performing a third computation by utilizing a result of said second computation, and thereby generating said key information which has been decrypted and a result of said computation on said usage information by utilizing said private key of said user; and

making said source available by utilizing said key information, wherein performing the first computation includes assuming the product of two large prime numbers to be a modulus, the two large prime numbers not being known to said user and, using said modulus, generating a first diagonal matrix having said encrypted key information and said usage information as components, and producing a second matrix from said first matrix, said second matrix being a different representation of said first matrix using an arbitrary basis.

8. A computer program product for use with a computer, said computer program product comprising:

a computer usable medium having computer readable program code means embodied in said medium for causing said computer to execute signature by a user on usage information of a source provided in a format made to be available by the use of key information, said computer program product having;

computer readable program code means for causing said computer to generate usage information which is to be signed;

computer readable program code means for causing said computer to perform a first computation by utilizing said key information which is encrypted and said usage information;

computer readable program code means for causing said computer to perform a second computation by utilizing a result of said first computation and a private key of said user;

computer readable program code means for causing said computer to perform a third computation by utilizing a result of said second computation, and thereby to generate a result of said computation performed on said key information which has been decrypted and said usage information by utilizing said private key of said user; and

computer readable program code means for making said source available by utilizing said key information, wherein said computer readable program code means for causing the computer to perform the first computation assumes the product of two large prime numbers to be a modulus, the two large prime numbers not being known to said user and, using said modulus, generates a first diagonal matrix having said encrypted key information and said usage information as components, and produces a second matrix from said first matrix, said second matrix being a different representation of said first matrix using an arbitrary basis.

9. A signature verification apparatus used for signing by a user on usage information of a source provided in a format made to be available by the use of key information, comprising:

means for generating said usage information which is to be signed;

means for performing a first computation by utilizing said key information which is encrypted and said usage information which is to be signed;

means for performing a third computation by utilizing a result of a second computation for decrypting key information and signing performed on a result of said first computation by utilizing a private key of said user, and thereby generating said key information which is decrypted and a result of said computation performed on said usage information by utilizing said private key of said user; and

means for making said source available by utilizing said decrypted key information, wherein said means for performing the first computation assumes the product of two large prime numbers to be a modulus, the two large prime numbers not being known to said user and, using said modulus, generates a first diagonal matrix having said encrypted key information and said usage information as components, and produces a second matrix from said first matrix, said second matrix being a different representation of said first matrix using an arbitrary basis.

10. The signature verification apparatus according to claim 9, further comprising:

a guarding device for guarding inside information from external access.

13. A signing apparatus used for signing by a user on usage information which shows using a source provided in a format made to be available by the use of key information, comprising:

means for inputting said key information encrypted by a key which makes a pair with a private key of said user;

means for storing said private key of said user;

means for generating usage information which is to be signed;

means for concatenating said encrypted key information, inputted by said means for inputting said key information, and said usage information generated by said means for generating usage information;

signing means for executing decryption of said encrypted key information of said concatenated information by utilizing said private key of said user stored in said means for storing, and for signing said usage information generated by said means for generating said usage information of said concatenated information by utilizing said private key of said user stored in said means for storing;

means for separating said information processed by said signing means into said decrypted key information and said usage information which has been signed; and

means for making said source available by utilizing said decrypted key information separated by said means for separating, wherein said means for concatenating assumes the product of two large prime numbers to be a modulus, the two large prime numbers not being known to said user and, using said modulus, generates a first diagonal matrix having said encrypted key information and said usage information as components, and produces a second matrix from said first matrix, said second matrix being a different representation of said first matrix using an arbitrary basis.