- 日時 : 2017.6.1(木)
- 場所 : E3-9F ミーティング室
- 講演者 : Yvo Desmedt
《Title》Parity Check based Redistribution of Secret Shares
《Abstract》Redistribution of shares need to happen when the adversary has hacked the computer of, e.g., two participants. Other motivations include longevity, a new administration, etc. In 2002, Wong-Wang-Wing presented a verifiable redistributing secret shares protocol, where the new parties must have been honest. They used Feldman's Verifiable Secret Sharing scheme, which assumed that the discrete logarithm is hard. In 2013, Nojoumian and Stinson presented information-theoretically (unconditionally) secure schemes under assumption that at most t out of 4t+1 parties are actively corrupt, where only the threshold (but not the number of parties) can be changed. We present an unconditionally secure solution assuming that at most t out of 3t+1 parties are actively corrupt. Our protocol uses properties of the parity-check matrix of the Generalized Reed-Solomon code. Moreover, we introduce a new open problem in the area of Reed-Solomon decoding.