A primary building block in designing adaptively secure protocols is a non-committing encryption or NCE that implements secure communication channels in the presence of adaptive corruptions. Current NCE constructions require a number of public key operations that grows linearly with the length of the message. Furthermore, general two-party protocols require a number of NCE calls that is linear in the circuit size (or otherwise the protocol is not round efficient). As a result the number of public key operations is inflated and depends on the circuit size as well.
In this paper we study the two-party setting in which at most one of the parties is adaptively corrupted, which we believe is the right security notion in the two-party setting. We study the feasibility of (1) NCE with constant number of public key operations for any message space. (2) Oblivious transfer with constant number of public key operations for any sender's input space, and (3) constant round secure computation protocols with a number of NCE calls, and an overall number of public key operations, that are independent of the circuit size. Our study demonstrates that such primitives indeed exist in the presence of single corruptions, while this is not the case for fully adaptive security (where both parties may get corrupted).Category / Keywords: cryptographic protocols / Secure Two-Party Computation, Adaptive Security, Non-Committing Encryption, Oblivious Transfer Date: received 13 Sep 2013 Contact author: arpitapatra10 at gmail com Available format(s): PDF | BibTeX Citation Version: 20130914:224451 (All versions of this report) Discussion forum: Show discussion | Start new discussion