2 research outputs found
An Improved Lower Bound on Oblivious Transfer Capacity via Interactive Erasure Emulation
We revisit the oblivious transfer (OT) capacities of noisy channels against
the passive adversary, which have been identified only for a limited class of
channels. In the literature, the general construction of oblivious transfer has
been known only for generalized erasure channels (GECs); for other channels, we
first convert a given channel to a GEC via alphabet extension and erasure
emulation, and then apply the general construction for GEC. In this paper, we
derive an improved lower bound on the OT capacity of the binary symmetric
channel (BSC) and binary symmetric erasure channel (BSEC) by proposing a new
protocol; by using interactive communication between the sender and the
receiver, our protocol emulates erasure events recursively in multiple rounds.
We also discuss a potential necessity of multiple rounds interactive
communication to attain the OT capacity.Comment: 6 pages, 2 figure
Complexity of Multi-Party Computation Functionalities
The central objects of secure multiparty computation are the “multiparty functions ” (or functionalities) that it seeks to securely realize. In this chapter we survey a set of results that constitute a Cryptographic Complexity Theory. This theory classifies and compares multiparty functions according to their secure computability and reducibility to each other. The basic questions studied, under various notions of security and reducibility, include: • Which functionalities are securely realizable (or are “trivial ” – i.e., can be reduced to any functionality)? • Which functionalities are “complete ” – i.e., those to which any functionality can be reduced? • More generally, which functionalities are reducible to which? Outside of triviality and completeness, this question is relatively less explored. Reductions yield relative measures of complexity among various functionalities. In the informationtheoretic setting, absolute complexity measures have also been considered. In particular, we discuss results regarding which functions have t-private protocols (in which security is required against a passive adversary corrupting t out of n players) and how this set changes as t increases from 1 to n. We treat separately the results on two-party functionalities, for which the cryptographic complexity i