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Yoshiki SAMESHIMA Hideaki SAISHO Kazuko OYANAGI Tsutomu MATSUMOTO
The authors present a multiparty signature generation (MSG) scheme of the Digital Signature Algorithm (FIPS 186-1). The scheme is based on a simple idea, however, it is much more convenient in usability in the real world than existing MSGs. The scheme has the following properties: (1) valid signatures are generated with odd n split private keys, (2) broadcast messages between the key holders are hidden from them, so that the n key holders do not need to process signature generation simultaneously, (3) even if up to t (= ) split keys are stolen, the adversary can get no information on the private key, (4) the scheme is as secure as the original signature algorithm against chosen message attack, and (5) the scheme is efficient in the sense that an implementation on smart card has demonstrated practical performance for interactive use with human user.