Patent Number 6816969
Issue Date 2004 11 09
Inventor(s) Miyazaki, Kunihiko
Sasaki, Ryoichi
Takaragi, Kazuo
Susaki, Seiichi
Mishima, Hisanori
Matsuki, Takeshi
Takeuchi, Kunihito
Iwamura, Mitsuru
Matsumoto, Tsutomu
State/Country JPX
Title: Digital signature generating method and digital signature verifying method
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. Exmp. Claim 1 Ex Claim text A method for sequentially generating digital signatures using n devices, each of said devices equipped with signature generator, said method comprising the steps of: generating a history data j when generating a j-th digital signature (j.gtoreq.1); storing, in m devices (1.ltoreq.m.ltoreq.n) out of said n devices involved in an i-th digital signature generating operation, said history data j; and generating an i-th digital signature i using at least one of the L (1.ltoreq.L