Secure Message Transmission Protocol Research Articles

Perfectly Secure Message Transmission Against Rational Adversaries

Secure Message Transmission (SMT) is a two-party cryptographic protocol by which the sender can securely and reliably transmit messages to the receiver using multiple channels. An adversary can corrupt a subset of the channels and commit eavesdropping and tampering attacks over the channels. In this work, we introduce a game-theoretic security model for SMT in which adversaries have some preferences for protocol execution. We define rational “timid” adversaries who prefer to violate security requirements but do not prefer the tampering to be detected. First, we consider the basic setting where a single adversary attacks the protocol. We construct perfect SMT protocols against any rational adversary corrupting all but one of the channels. Since minority corruption is required in the traditional setting, our results demonstrate a way of circumventing the cryptographic impossibility results by a game-theoretic approach. Next, we study the setting in which all the channels can be corrupted by multiple adversaries who do not cooperate. Since we cannot hope for any security if a single adversary corrupts all the channels or multiple adversaries cooperate maliciously, the scenario can arise from a game-theoretic model. We also study the scenario in which both malicious and rational adversaries exist.

On minimal connectivity requirements for secure message transmission in directed networks

In a synchronous distributed network of n nodes, the goal of a Secure Message Transmission (SMT) protocol is to securely deliver the sender's message at the receiver's end in the presence of a computationally unbounded adversary that can partially control the network by corrupting some of its nodes (except the sender and the receiver). In a network modelled as a directed graph, to achieve unconditional security tolerating tb Byzantine faults, it is known that: (1) if all the paths are one-way connected from the sender to the receiver – called as forward channels – then2tb+1 vertex-disjoint forward channels are necessary and sufficient (2) for 1≤u≤tb, if there exist 2tb+1−u vertex-disjoint forward channels then u vertex-disjoint paths from the receiver to the sender – known as feedback channels – are necessary and sufficient. Moreover, similar characterization exists for tolerating mixed faults – up to tf fail-stop faults in addition to tp passive faults.We notice that these results characterized the networks by studying the required number of extra vertex-disjoint feedback channels, conditioned on the existence of a certain number of forward channels. In this work, we give a generic characterization without attaching any such if condition. Specifically, we answer the following questions. In a given directed graph, that is abstracted as a collection of strong paths from S to R and R to S, under what conditions is SMT (im)possible tolerating: (1) up to tp passive faults?, (2) mixed faults – up to tf fail-stop faults in addition to tp passive faults?, and (3) up to tb Byzantine faults? Also, for each of these three problems, we explicitly show that there are networks in which SMT protocols exist whereas the existing results do not characterize such networks.

A Model for Adversarial Wiretap Channels

In the wiretap model of secure communication, Alice is connected to Bob over a noisy channel that is eavesdropped by Eve. The goal is to provide (asymptotic) reliability and perfect secrecy assuming that the Eve has unlimited computational power. The model has attracted considerable attention in recent years because it provides a natural model for passive eavesdropping in wireless communication. We consider a wiretap model with active adversaries, and define adversarial wiretap (AWTP) channels using a $(\rho _{r} , \rho _{w})$ wiretap adversary who can read a fraction $\rho _{r}$ , and modify a fraction $\rho _{w}$ of a sent codeword. The code components that are read and/or modified can be chosen adaptively, and the subsets of read and modified components could be different. AWTP codes provide secrecy and reliability for communication over AWTP channels. We define the security and reliability of AWTP channels and use these definitions to evaluate the security and reliability of codes for these channels. This paper has two main contributions. First, we prove an upper bound on the rate of AWTP codes for $(\rho _{r} , \rho _{w})$ -AWTP channels. Second, we give an explicit construction of a perfectly secure AWTP code family with efficient decoding that achieves the bound and, hence, obtain the secrecy capacity of AWTP channels for large alphabets. AWTP model is a natural extension of Wyner’s wiretap models, and somewhat surprisingly, it is also closely related to a seemingly unrelated cryptographic primitive, secure message transmission (SMT). This relation results in a new (and the only known) bound on the transmission rate of 1-round $(\epsilon , \delta )$ -SMT protocols. We discuss our results, give their relations to other works, and propose directions for future work.

Network Connection and Perfectly Secure Message Transmission on Wireless Mobile Networks

In this paper we proposed perfectly secure message transmission for reliable and secure communications in order to ensure that an adversary cannot obtain information (in the information theoretic sense) about messages. There are numerous studies about the interplay of network connectivity and perfectly secure message transmission under a Byzantine adversary capable of corrupting up to t players. It is known that perfectly secure communication among any pair of players is possible if and only if the underlying synchronous wired network is (2t+1)-connected. But existing studies deal with traditional wired networks and neglect perfectly secure message transmission on mobile networks. Therefore, we proposed a perfectly secure message transmission protocol and analyzed the interplay of mobile network connectivity and perfectly secure message transmission. We considered that network connection takes priority over other factors for perfectly secure message transmission, and we showed that the number of paths needed to ensure mobile network connection is   n K n N log = in an undirected graph with n nodes. And, we proved that the connectivity (2T+1) on mobile networks with n nodes, where   n K t T log = , must be higher than the connectivity (2t+1) of wired networks.

Unconditionally reliable and secure message transmission in undirected synchronous networks: possibility, feasibility and optimality

We study the interplay of network connectivity and the issues related to the 'possibility', 'feasibility' and 'optimality' for unconditionally reliable message transmission (URMT) and unconditionally secure message transmission (USMT) in an undirected synchronous network, under the influence of an adaptive mixed adversary having unbounded computing power, who can corrupt some of the nodes in the network in Byzantine, omission, fail-stop and passive fashion respectively. We consider two types of adversary, namely threshold and non-threshold. One of the important conclusions we arrive at from our study is that allowing a negligible error probability significantly helps in the 'possibility', 'feasibility' and 'optimality' of both reliable and secure message transmission protocols. To design our protocols, we propose several new techniques which are of independent interest.

Perfectly Reliable Message Transmission

We consider the problem of reliable message transmission between two synchronous players connected by n wires, some t < n 2 of which may be faulty. We show how to get reliability “for free”—reliable transmission of b bits involves a total communication of only O ( b ) bits, when b is large enough. We also construct an efficient Perfectly Secure Message Transmission Protocol.