Digital signing method

• US 7,770,009 B2
• Filed: 12/04/2007
• Issued: 08/03/2010
• Est. Priority Date: 10/22/1999
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sakai, Mizuhiro, Susaki, Seiichi, Sasaki, Ryoichi, Moritsu, Toshiyuki, Matsumoto, Tsutomu, Iwamura, Mitsuru, Miyazaki, Kunihiko, Takaragi, Kazuo
• Primary Examiner(s): Hoffman; Brandon S
• Application Number:
  US11/999,373
• Publication Number:
  US 20080098232A1
• Time in Patent Office: 973 Days
• Field of Search: None
• US Class Current: 713/170
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 9/321 involving a third party or a trusted authority
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04L 9/3297 involving time stamps, e.g. generation of time stamps

Abstract

According to the invention, techniques for authenticating that a digitally signed document is genuine. Specific embodiments according to the present invention can determine whether a digital signature was generated by a digital signature generator, or if the digital signature was generated by a third party posing as the digital signature generator. Specific embodiments can provide independent verification of digital signer identity based upon prior signed messages, time/date stamps, and the like. Techniques according to the present invention can be embodied in methods, apparatus, computer software and systems.

Claims

1. A digital signing method, comprising:

providing a log list comprising previously generated digital signatures;

computing a computed hash value of inputted data including a message to be signed or a hash value thereof, the inputted data further including only a most recently generated digital signature obtained from the log list or a hash value thereof;

encoding the computed hash value of the inputted data to produce encoded data of a predetermined format that is suitable for encryption processing for generating a digital signature;

applying a secret key to the encoded data to generate a digital signature;

distributing a signature-attached message including the generated digital signature, the message to be signed, and the most recently generated digital signature obtained from the log list or the hash value thereof; and

registering the generated digital signature as log data with the log list.

2. The method of claim 1 wherein said log data further comprises a distribution destination associated therewith.

3. The method of claim 1 further comprising registering the log data with said log list only when the data from a previously signed message is included in the latest log data that is registered with said log list.

4. A computer-readable storage medium having stored thereon computer-executable program to conduct digital signing using a computer, said computer-executable program causing said computer to:

provide a log list comprising previously generated digital signatures;

compute a computed hash value of inputted data including a message to be signed or a hash value thereof, the inputted data further including only a most recently generated digital signature obtained from the log list or a hash value thereof;

encode the computed hash value of the inputted data to produce encoded data of a predetermined format that is suitable for encryption processing for generating a digital signature;

apply a secret key to the encoded data to produce a generated digital signature;

register as log data the generated digital signature in the log list; and

distribute a signature-attached data including the generated digital signature, the message to be signed, and the most recently generated digital signature obtained from the log list or the hash value thereof.

5. The computer-readable storage medium of claim 4, wherein said log data further comprises a distribution destination associated therewith.

6. The computer-readable storage medium of claim 4, wherein said computer-executable program further causes said computer to register the log data with said log list only when the data from a previously signed message is included in the latest log data that is registered with said log list.

7. A computer-executable program that executes a digital signing method using a computer, said digital signing method comprising:

providing a log list comprising previously generated digital signatures;

computing a computed hash value of inputted data including a message to be signed or a hash value thereof, the inputted data further including only a most recently generated digital signature obtained from the log list or a hash value thereof;

encoding the computed hash value of the inputted data to produce encoded data of a predetermined format that is suitable for encryption processing for generating a digital signature;

applying a secret key to the encoded data to produce a generated digital signature;

registering as log data the generated digital signature in the log list; and

distributing a signature-attached data including the generated digital signature, the message to be signed, and the most recently generated digital signature obtained from the log list or the hash value thereof.

8. The computer-executable program of claim 7, wherein said log data further comprises a distribution destination associated therewith.

9. The computer-executable program of claim 7, wherein said digital signing method further comprises registering the log data with said log list only when the data from a previously signed message is included in the latest log data that is registered with said log list.