To enable the assignment of signature sequence capable of embodying the speed up of calculation and the simplification of a program by managing the public key at a signature certifier which does not depend on the combinations over the entire part of signers and the signature sequence.
The multiple digital signature system consists of n (n is an integer of ≥2) persons of the signers U1, U2,..., Un and the signature certifier V. The signers U1, U2,..., Un are provided with a signature forming device 10. The signature certifier V is provided with a signature certifying device 40. Messages are signed by n persons of the signers in the assigned signature sequence of U1*U2*...*Un, by which the multiple digital signatures are formed. The last signer Un transmits the multiple digital signatures to the signature certifier V. The signature certifier V certifies that the multiple digital signatures are the signatures formed by the signers U1, U2,..., Un to the messages and that the signature sequence is U1*U2*...*Un.
SENDA TAKAYUKI
SHIZUTANI HIROKI
NISHIZEKI TAKAO
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