Non-committing encryption achieved only semantic security,in contrast,applications often require security against chosen ciphertext attacks.A main ingredient in the previous adaptive universally composable(UC)oblivious transfer protocols are non-committing encryptions.the previous proposals are not UC secure against adaptive adversaries in the so-called non-erase model.A new UC secure oblivious transfer protocols were proposed and schemes utilize two primitives of the verifiably smooth projective hashing and deniable encryption as constructed by.the double trapdoor decryption mechanism based on trapdoor commitment.Our construction is based on the decisional composite residuosity in common reference string (CRS) model.We constructed a two-message(1-round) string oblivious transfer protocol,which improves computational efficient that supports message spaces of size exponential and save O(n)-1 rounds communications efficient than bit-OT protocols.
A new oblivious transfer protocol was proposed within the framework of universally composable security(UC-DT).The protocol based on the verifiably smooth projective hashing(VSPH) is against adaptive adversaries in a common reference string(CRS) model.The UC-OT protocol improves computational efficiency with non-committing encryptions(NCE)which is based on decisional compounding residuosity,achieves UC-OT,and it saves O(n)-1 rounds in communication efficiency than bit-OT protocols.Compared with Canetti’s scheme in non-erase model,the message reduced once.Compared with Fischlin’s scheme,the message transfers were reduced twice,and the scheme does not rely on the auxiliary party,therefore it is more practical.
In a seminal work, Ishai et al. (FOCS-2006) studied the viability of designing unconditionally secure protocols for key agreement and secure multi-party computation (MPC) using an anonymous bulletin board (ABB) as a building block. While their results establish the feasibility of key agreement and honest-majority MPC in the ABB model, the optimality of protocols with respect to their round and communication complexity is not studied. This paper enriches this study of unconditional security in the ABB model in multiple ways. •We present a key agreement protocol with a novel combinatorial insight to offer a 200% throughput over the (FOCS-2006) study; i.e., using the same number of messages, we can (almost) double the bit-length of the agreed key. We also prove the near optimality of our approach. •We offer unconditionally secure protocols for the (random) string oblivious transfer functionalities. We present a 1-round chosen message random string oblivious transfer and show how to extend it to a non-interactive (random) string oblivious transfer protocol and a 2-round chosen message string oblivious transfer. •We prove a 1-round communication lower bound for BEC under certain conditions. Central to our technical contributions is the abstraction of a distributional variant of the random ABB functionality. Investigating the concrete efficiency of founding MPC from this primitive leads to fascinating new mathematical challenges in well-established MPC models, which will be of broader interest to the community.