Patent ID: 11888977
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Digital communication (Electrical engineering)
Classification: CPC H  G | IPC H

Claim 1:
2. The share converting device according to claim 1, wherein
v is an integer greater than or equal to 1, ceil is a ceiling function, a member yd can be divided into m(d) sub-members (yd)0, . . . , (yi)m(d)-1, m′(d) is ceil(m(d)/v), and (y′d)j is ((yd)vj, (yd)vj+1, . . . , (yd)v(j+1)−1) ∈Fv belonging to a set Fv,
the share SSi, which is accepted by the first input unit, further contains N−1 arbitrary values rd∈Fv, where d∈{0, . . . , N−1} and d≠i, which belong to the set Fv and a checksum ci−1 mod N∈Fv, and
the share converting device includes processing circuitry configured to:
obtain a share [cd]i of a checksum cd=Σ0≤j<m′(d)−1{(y′d)jrdj+1}+(y′d)m′(d)−1rdm′(d)+1∈Fv in accordance with Shamir's secret sharing scheme by secure computation using the arbitrary values rd and the shares [yd]j,
output the share [cd]i to another share converting device Ad+1 mod N,
accept a share [ci−1 mod N]d, and
verify whether the checksum ci−1 mod N and the share [ci−1 mod N]d have a right relationship.