International Association for Cryptologic Research (IACR)
Abstract
We propose cryptographic primitives for reading and assigning the
(shared) secret found at a secret index in a vector of secrets. The
problem can also be solved in constant round with existing general
techniques based on arithmetic circuits and the ``equality test\u27\u27
in [Damgard.et.al 05]. However the proposed technique requires to
exchange less bits. The proposed primitives require a number of rounds
that is independent of the size N of the vector, and only depends
(linearly) on the number t of computing servers. A previously known
primitive for reading a vector at a secret index works only for
2-party computations. Our primitives work for any number of computing
participants/servers.
The proposed techniques are secure against passive attackers, and zero
knowledge proofs are provided to show that exactly one index of the array is read/written. The techniques work both with multiparty computations based on secret sharing and with multiparty computations based on threshold homomorphic encryption