Abstract

Biometric signal consisting of irrelevant or non-distinctive features can contain useful correlational properties that privacy-preserving verification schemes can exploit. While an efficient protocol for iris verification using noise has been presented, it is not applicable to other widely used modalities, i.e., face and fingerprint, since the methods of noise extraction and comparison are different. In this work, we design a verification protocol for secure dot product computation and also propose noise extraction mechanisms for face and fingerprint modalities. We evaluate the performance of the protocol on CFP, LFW, CelebA, FVC 2004 DB1A, DB2A, DB3A, and SOCOFing datasets. While the protocol exhibits a slight degradation in accuracy, it provides information-theoretic security with a practical computational complexity.

Abstract

Biometric noise is often discarded in many biometric template protection systems. However, the noise ratio be- tween two templates encodes specific correlational proper- ties that template protection schemes can exploit. Biometric authentication usually occurs between mutually distrusting parties, which calls for privacy-preserving techniques. In this paper, we propose a novel biometric authentication pro- tocol, SIAN(Secure Iris Authentication using Noise), adapt- ing secure two-party computation and incorporating un- certainty constraints from biometric noise for security. We evaluate it on three iris datasets: MMU v1, Ubiris v1, and IITD v1, and observe a low EER degradation. The pro- posed protocol has information-theoretic security and low computational complexity, making it suitable for practical real-time applications.

Abstract

Threshold signature schemes allow any qualified subset of participants (t-out-of-n) to combine its shares and generate a signature that can be verified using a single threshold public key. While there are several existing threshold signature schemes, most are either n-out-of-n and/or require consistent availability of the exact same set of participants through several rounds. This can result in signer availability becoming a bottleneck in the signing process. Our threshold signature scheme removes this dependence by introducing truly threshold asynchronous signatures, i.e., once the message to be signed has been revealed, the signers simply sign and broadcast their signature. Our scheme also uses misbehaviour detection to impose accountability for invalid signing. We prove that our scheme is safe against known distributed attacks and is EUF−CMA secure in the Random Oracle Model for up to t−1 malicious participants.

Abstract

Blockchains lie at the heart of Bitcoin and other cryptocurrencies that have shown great promise to revolutionize finance and commerce. Although they are gaining increasing popularity, they face technical challenges when it comes to scaling to support greater demand while maintaining their desirable security properties. In an exciting line of recent work, many researchers have proposed various scalable blockchain protocols that demonstrate the potential to solve these challenges. However, many of these protocols come with the assumptions of honest majority and symmetric network access which may not accurately reflect the real world where the participants may be self-interested or rational. Secondly, these works show that their protocol works in an ideal environment where each party has equal access to the network whereas different parties have varying latencies and network speeds. These assumptions may render the protocols susceptible to security threats in the real world, as highlighted by the literature focused on exploring gametheoretic attacks on these protocols. We propose a scalable blockchain protocol, Interlude, which comes with the typical security guarantees while focusing on game-theoretic soundness and network fairness. The novelty of Interlude is that it has a relatively simple design consisting of a sequence of parallel blocks containing disjoint transaction sets that can be mined quickly followed by a series block that is slow to mine and gives the honest parties in the network time to synchronize. Thus, between the chaos of parallel blocks, our blockchain protocol masquerades an interlude moment of harmony in series blocks that synchronize the network.

Abstract

In Quantum secret sharing we can share both quantum and classical secrets with a quantum resource. In this article we study the problem of revocation of quantum secret shared by the dealer with two shareholders in a three party scenario. In the existing secret sharing protocols there are no means by which the dealer can retrieve back the secret once he/she finds all the share holders to be dishonest. Our protocol makes a significant advancement in solving this problem by designing strategy in bringing back the secret in the worst possible situation when all the shareholders/receivers are dishonest1. In our proposed strategy the dealer also possesses a quantum share of the secret which empowers the dealer to bring back the secret even after sharing is done. However the protocol along with the revocation process also ensures the normal reconstruction at the share holder’s location when they are honest. This advantage comes with the expense of extra one qubit on dealer’s side and consequently we require a four qubit resource to start with for 1-dealer and 2-share holder’s scenario. Here in this article we not only give the description of our protocol but also give an example where our protocol is working with the help of a four qubit entangled state. We also explicitly found out the range of parameter for the input state for which the protocol will be successful.

Abstract

An extensive research of MPC protocols in different adversarial settings over the past few years has led to various improvements in this domain. Goyal et al.[14] in their paper addressed the issue of an efficient MPC protocol in active adversarial setting by removing the dependency on multiplication depth Dm in the arithmetic circuit. This development was followed by Hirt et al.[16] which proposed an efficient MPC protocol tolerating mixed adversary with communication complexity of O ((ci+ cm+ co) nκ+ ciBA (κ)+ Dm (n3κ+ nBA (κ))) bits, where Dm is the multiplicative depth of the circuit and κ is the size of an element in the field. Additionally, Hirt et al.[16], proposed an open problem to construct a protocol for the mixed adversarial setting, independent of the multiplicative depth Dm, with linear communication complexity. In this paper, we resolve this problem in the affirmative by providing an efficient MPC protocol in the mixed adversarial setting independent of the multiplicative depth of the circuit.

Abstract

In a distributed network, we consider two special nodes called the sender S and the receiver R that are connected by n node-disjoint (except for S and R) bi-directional wires. Out of these n wires, the adversary can control at most t wires (of its choice) in Byzantine fashion. In this setting, our goal is to design a message transmission protocol Π that assures the following two conditions hold: (1) by the end of the protocol Π, R gets the correct message m transmitted by S without any error (perfect reliability), and (2) the adversary learns no information aboutm, whatsoever, in information theoretic sense (perfect secrecy). Protocols that satisfy these two conditions are known as the Perfectly Secure Message Transmission (PSMT) protocols.

Abstract

As the “Internet communications infrastructure” develops to encircle smart devices, it is very much essential for designing suitable methods for secure communications with these smart devices, in the future Internet of Things (IoT) applications context. Due to wireless communication among the IoT smart devices and the gateway node (GWN), several security threats may arise in the IoT environment, including replay,man-in-the-middle, impersonation, malicious devices deployment,and physical devices capture attacks. In this article, to mitigate such security threats, we design a new certificate-based device access control scheme in IoT environment which is not only secure against mentioned attacks, but it also preserves anonymity property. A detailed security analysis using the widely accepted real-or-random (ROR) model-based formal security analysis, informal security analysis, and also formal security verification based on the broadly accepted automated validation of Internet security protocols and applications (AVISPAs) tool has been performed on the proposed scheme to show that it is secure against various known attacks. In addition, a comprehensive comparative analysis among the proposed scheme and other relevant schemes shows that a better trade off among the security and functionality attributes, communication, and computational costs is achieved for the proposed scheme as compared to other schemes.

Abstract

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 – then 2tb + 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 t f 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 t f 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.

Abstract

In a network of n nodes (modelled as a digraph), the goal of a perfectly secret message transmission (PSMT) protocol is to replicate sender’s message m at the receiver’s end without revealing any information about m to a computationally unbounded adversary that eavesdrops on any t nodes. The adversary may be mobile too – that is, it may eavesdrop on a different set of t nodes in different rounds. We prove a necessary and sufficient condition on the synchronous network for the existence of r-round PSMT protocols, for any given r > 0; further, we show that round-optimality is achieved without trading-off the communication complexity; specifically, our protocols have an overall communication complexity of O(n) elements of a finite field to perfectly transmit one field element. Apart from optimality/scalability, two interesting implications of our results are: (a) adversarial mobility does not affect its tolerability: PSMT tolerating a static tadversary is possible if and only if PSMT tolerating mobile t-adversary is possible; and (b) mobility does not affect the round optimality: the fastest PSMT protocol tolerating a static t-adversary is not faster than the one tolerating a mobile t-adversary.