Digital signature generating method and digital signature verifying method

(54) DIGITAL SIGNATURE GENERATING METHOD AND DIGITAL SIGNATURE VERIFYING METHOD

(75) Inventors: Kunihiko Miyazaki, Yokohama (JP);

Ryoichi Sasaki, Fujisawa (JP); Kazuo
Takaragi, Ebina (JP); Seiichi Susaki,
Yokohama (JP); Hisanori Mishima,
Yokohama (JP); Takeshi Matsuki,
Musashino (JP); Kunihito Takeuchi,
Yokosuka (JP); Mitsuru Iwamura,
Tokyo (JP); Tsutomu Matsumoto,
Yokohama (JP)

(73) Assignee: Hitachi, Ltd., Tokyo (JP)

( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 711 days.

(21) Appl. No.: 09/797,260

(22) Filed: Feb. 28, 2001

(65) Prior Publication Data

US 2002/0108044 Al Aug. 8, 2002 (30) Foreign Application Priority Data

Dec. 7, 2000 (JP) 2000-377990

(51) Int. CI.7 G06F 17/00

(52) U.S. CI 713/180; 713/178; 713/176

(58) Field of Search 713/168-181,

713/150-154

(56) References Cited

U.S. PATENT DOCUMENTS

5,136,646 A 8/1992 Haber et al.
5,956,404 A 9/1999 Schneier et al.

6,738,902 Bl * 5/2004 Ruppert et al 713/162

6,738,912 B2 * 5/2004 Buttiker 713/201

6,748,529 B2 * 6/2004 Smith 713/153

FOREIGN PATENT DOCUMENTS

JP 3278721 B 2/2002

OTHER PUBLICATIONS

Campbell, Supporting digital signatures in mobile environments, Enabling Technologies: Infrastructures for Collaborative Enterprises, 2003, Twelfth IEEE International Workshops on, Jun. 9-11, 2003, pp. 238-242.* Yen et al., Fast algorithms for LUC digital signature computation, Computers and Digital Techniques, IEE Proceedings, vol. 142, Issue 2, Mar. 1995, pp. 165-169.* Wong et al., Digital signatures for flows and multicasts, Networking, IEEE/ACM Transactions on, vol. 7, Issue 4, Aug. 1999, pp. 502-513.*

* cited by examiner

Primary Examiner—David Jung

(74) Attorney, Agent, or Firm—Townsend and Townsend and Crew LLP

(57) ABSTRACT

In a signature generating method where not necessarily all of a plurality of signature generating devices work together each time to generate signatures, the present invention seeks to correctly and securely reflect data relating to previous signatures.

When generating signatures, the data used for the next signature is sent beforehand to the other signature generating devices. Also, when generating signatures, at least one of the devices is used consecutively, thus allowing history data to be shared during signature generation.

13 Claims, 10 Drawing Sheets