In this paper, we investigate the security of lightweight block ciphers, focusing on those that utilize the ADD-Rotate-XOR (ARX) and AND-Rotate-XOR (AND-RX) design paradigms. More specifically, we examine their resilience against boomerang-style attacks. First, we propose an automated search strategy that leverages the boomerang connectivity table (BCT) for AND operations ($\wedge BCT$) to conduct a complete search for boomerang and rectangle distinguishers for AND-RX ciphers. The proposed...

Offline payments present an opportunity for central bank digital currency to address the lack of digital financial inclusion plaguing existing digital payment solutions. However, the design of secure offline payments is a complex undertaking; for example, the lack of connectivity during the payments renders double spending attacks trivial. While the identification of double spenders and penal sanctions may curb attacks by individuals, they may not be sufficient against concerted efforts by...

Topology-hiding broadcast (THB) enables parties communicating over an incomplete network to broadcast messages while hiding the network topology from within a given class of graphs. Although broadcast is a privacy-free task, it is known that THB for certain graph classes necessitates computational assumptions, even against "honest but curious" adversaries, and even given a single corrupted party. Recent works have tried to understand when THB can be obtained with information-theoretic (IT)...

In this short note we examine one of the impossible boomerang distinguishers of Skinny-128-384 provided by Zhang, Wang and Tang at ToSC 2024 Issue 2 and disprove it. The issue arises from the use of the Double Boomerang Connectivity Table (DBCT) as a tool to establish that a boomerang switch over 2 rounds has probability zero, whereas the DBCT only covers specific cases of difference propagation, missing a large set of events that might make the connection possible. We study in...

The impossible boomerang attack (IBA) is a combination of the impossible differential attack and boomerang attack, which has demonstrated remarkable power in the security evaluation of AES and other block ciphers. However, this method has not received sufficient attention in the field of symmetric cipher analysis. The only existing search method for impossible boomerang distinguishers (IBD), the core of IBAs, is the $\mathcal{UB}\text{-method}$, but it is considered rather rudimentary given...

We study the problem of implementing unconditionally secure reliable and private communication (and hence secure computation) in dynamic incomplete networks. Our model assumes that the network is always $k$-connected, for some $k$, but the concrete connection graph is adversarially chosen in each round of interaction. We show that, with $n$ players and $t$ malicious corruptions, perfectly secure communication is possible if and only if $k > 2t$. This disproves a conjecture from earlier...

Differential-linear cryptanalysis was introduced by Langford and Hellman in 1994 and has been extensively studied since then. In 2019, Bar-On et al. presented the Differential-Linear Connectivity Table (DLCT), which connects the differential part and the linear part, thus an attacked cipher is divided to 3 subciphers: the differential part, the DLCT part, and the linear part. In this paper, we firstly present an accurate mathematical formula which establishes a relation between...

Understanding the fault tolerance of Byzantine Agreement protocols is an important question in distributed computing. While the setting of Byzantine faults has been thoroughly explored in the literature, the (arguably more realistic) omission fault setting is far less studied. In this paper, we revisit the recent work of Loss and Stern who gave the first protocol in the mixed fault model tolerating $t$ Byzantine faults, $s$ send faults, and $r$ receive faults, when $2t+r+s<n$ and omission...

Machine learning (ML) as a service has emerged as a rapidly expanding field across various industries like healthcare, finance, marketing, retail and e-commerce, Industry 4.0, etc where a huge amount of data is gen- erated. To handle this amount of data, huge computational power is required for which cloud computing used to be the first choice. However, there are several challenges in cloud computing like limitations of bandwidth, network connectivity, higher latency, etc. To address...

In symmetric cryptography, vectorial Boolean functions over finite fields F2n derive strong S-boxes. To this end, the S-box should satisfy a list of tests to resist existing attacks, such as the differential, linear, boomerang, and variants. Several tables are employed to measure an S- box’s resistance, such as the difference distribution table (DDT) and the boomerang connectivity table (BCT). Following the boomerang attacks recently revisited in terms of the boomerang switch effect, with a...

Evolving secret-sharing schemes, defined by Komargodski, Naor, and Yogev [TCC 2016B, IEEE Trans. on Info. Theory 2018], are secret-sharing schemes in which there is no a-priory bound on the number of parties. In such schemes, parties arrive one by one; when a party arrives, the dealer gives it a share and cannot update this share in later stages. The requirement is that some predefined sets (called authorized sets) should be able to reconstruct the secret, while other sets should learn no...

The security level of a cipher is a key parameter. While general-purpose quantum computers significantly threaten modern symmetric ciphers, other quantum approaches like quantum annealing have been less concerning. However, this paper argues that a quantum annealer specifically designed to attack Grain 128 and Grain 128a ciphers could soon be technologically feasible. Such an annealer would require 5,751 (6,751) qubits and 77,496 (94,708) couplers, with a qubit connectivity of 225 (249)....

Recent constructions of (tweakable) block ciphers with an embedded cryptographic backdoor relied on the existence of probability-one differentials or perfect (non-)linear approximations over a reduced-round version of the primitive. In this work, we study how the existence of probability-one differentials or perfect linear approximations over two rounds of a substitution-permutation network can be avoided by design. More precisely, we develop criteria on the s-box and the linear layer that...

Distributed integrated circuit (IC) supply chain has resulted in a myriad of security vulnerabilities including that of hardware Trojan (HT). An HT can perform malicious modifications on an IC design with potentially disastrous consequences, such as leaking secret information in cryptographic applications or altering operation instructions in processors. Due to the emergence of outsourced fabrication, an untrusted foundry is considered the most potent adversary in introducing an HT. This can...

In Addition-Rotation-Xor (ARX) ciphers, the large domain size obstructs the application of the boomerang connectivity table. In this paper, we explore the problem of computing this table for a modular addition and the automatic search of boomerang characteristics for ARX ciphers. We provide dynamic programming algorithms to efficiently compute this table and its variants. These algorithms are the most efficient up to now. For the boomerang connectivity table, the execution time is $4^2(n −...

On the Internet of Connected Vehicles, a vehicle has to communicate bi-directionally with several devices for establishing a shared network for inter-vehicle and intra-vehicle connectivity. These connection protocols are commonly structured to connect all the individual components with an implicit degree of trust, which is supposed to protect the whole system from unauthorized users. Technologies like Automotive Ethernet tend to increase security by reducing the implicit trust within the...

The double boomerang connectivity table (DBCT) is a new table proposed recently to capture the behavior of two consecutive S-boxes in boomerang attacks. In this paper, we observe an interesting property of DBCT of S-box that the ladder switch and the S-box switch happen in most cases for two continuous S-boxes, and for some S-boxes only S-box switch and ladder switch are possible. This property implies an additional criterion for S-boxes to resist the boomerang attacks and provides as well a...

Secure message transmission (SMT) constitutes a fundamental network-layer building block for distributed protocols over incomplete networks. More specifically, a sender $\mathbf{S}$ and a receiver $\mathbf{R}$ are connected via $\ell$ disjoint paths, of which at most $t$ paths are controlled by the adversary. Perfectly-secure SMT protocols in synchronous and asynchronous networks are resilient up to $\ell/2$ and $\ell/3$ corruptions respectively. In this work, we ask whether it is...

The 5G mobile communication network provides seamless communications between users and service providers and promises to achieve several stringent requirements, such as seamless mobility and massive connectivity. Although 5G can offer numerous benefits, security and privacy issues still need to be addressed. For example, the inclusion of small cell networks (SCN) into 5G brings the network closer to the connected users, providing a better quality of services (QoS), resulting in a significant...

The Keccak sponge function family, designed by Bertoni et al. in 2007, was selected by the U.S. National Institute of Standards and Technology (NIST) in 2012 as the next generation of Secure Hash Algorithm (SHA-3). Due to its theoretical and practical importance, cryptanalysis against SHA-3 has attracted an increasing attention. To the best of our knowledge, the most powerful collision attack on SHA-3 up till now is the linearisation technique proposed by Jian Guo et al. However, that...

In a ring-signature-based anonymous cryptocurrency, signers of a transaction are hidden among a set of potential signers, called a ring, whose size is much smaller than the number of all users. The ring-membership relations specified by the sets of transactions thus induce bipartite transaction graphs, whose distribution is in turn induced by the ring sampler underlying the cryptocurrency. Since efficient graph analysis could be performed on transaction graphs to potentially deanonymise...

WARP is an energy-efficient lightweight block cipher that is currently the smallest 128-bit block cipher in terms of hardware. It was proposed by Banik et al. in SAC 2020 as a lightweight replacement for AES-128 without changing the mode of operation. This paper proposes key-recovery attacks on WARP based on differential cryptanalysis in single and related-key settings. We searched for differential trails for up to 20 rounds of WARP, with the first 19 having optimal differential...

Use of game theory and mechanism design in cloud security is a well-studied topic. When applicable, it has the advantages of being efficient and simple compared to cryptography alone. Most analyses consider two-party settings, or multi-party settings where coalitions are not allowed. However, many cloud security problems that we face are in the multi-party setting and the involved parties can almost freely collaborate with each other. To formalize the study of disincentivizing coalitions...

A secret sharing scheme enables the dealer to share a secret among $n$ parties. A classic secret sharing scheme takes the number $n$ of parties and the secret as the input. If $n$ is not known in advance, the classic secret sharing scheme may fail. Komargodski, Naor, and Yogev \cite[TCC 2016]{KNY16} first proposed the evolving secret sharing scheme that only takes the secret as the input. In the work \cite[TCC 2016]{KNY16}, \cite[TCC 2017]{KC17} and \cite[Eurocrypt 2020]{BO20}, evolving...

Recently, Bar-On et al. introduced at Eurocrypt’19 a new tool, called the differential-linear connectivity table (DLCT), which allows for taking into account the dependency between the two subciphers E_0 and E_1 involved in differential-linear attacks. This paper presents a theoretical characterization of the DLCT, which corresponds to an autocorrelation table (ACT) of a vectorial Boolean function. We further provide some new theoretical results on ACTs of vectorial Boolean functions.

The proliferation of the Internet of Things (IoT) technology has made ubiquitous computing a reality by broadening Internet connectivity across diverse application domains, thus bridging billions of devices and human beings as well for information collection, data processing, and decision-making. In recent years, IoT technology and its applications in various industrial sectors have grown exponentially. Most existing industrial IoT (IIoT) implementations, however, are still relying on a...

Machine learning aided cryptanalysis is an interesting but challenging research topic. At CRYPTO'19, Gohr proposed a Neural Distinguisher (ND) based on a plaintext difference. The ND takes a ciphertext pair as input and outputs its class (a real or random ciphertext pair). At EUROCRYPTO'20, Benamira et al proposed a deeper analysis of how two specific NDs against Speck32/64 work. However, there are still three research gaps that researchers are eager to fill in. (1) what features related to...

During the last years, many Physical Zero-knowledge Proof(ZKP) protocols for Nikoli’s puzzles have been designed. In this paper, we propose two ZKP protocols for the two Nikoli’s puzzles called Nurikabe and Hitori. These two puzzles have some similarities, since in their rules at least one condition requires that some cells are connected to each other, horizontally or vertically. The novelty in this paper is to propose two techniques that allow us to prove such connectivity without...

Topology-hiding broadcast (THB) enables parties communicating over an incomplete network to broadcast messages while hiding the topology from within a given class of graphs. THB is a central tool underlying general topology-hiding secure computation (THC) (Moran et al. TCC’15). Although broadcast is a privacy-free task, it was recently shown that THB for certain graph classes necessitates computational assumptions, even in the semi-honest setting, and even given a single corrupted party. In...

The differential-linear attack, combining the power of the two most effective techniques for symmetric-key cryptanalysis, was proposed by Langford and Hellman at CRYPTO 1994. From the exact formula for evaluating the bias of a differential-linear distinguisher (JoC 2017), to the differential-linear connectivity table (DLCT) technique for dealing with the dependencies in the switch between the differential and linear parts (EUROCRYPT 2019), and to the improvements in the context of...

We investigate special structures due to automorphisms in isogeny graphs of principally polarized abelian varieties, and abelian surfaces in particular. We give theoretical and experimental results on the spectral and statistical properties of (2, 2)-isogeny graphs of superspecial abelian surfaces, including stationary distributions for random walks, bounds on eigenvalues and diameters, and a proof of the connectivity of the Jacobian subgraph of the (2, 2)-isogeny graph. Our results improve...

A graph signature scheme is a digital signature scheme that allows a recipient to obtain a signature on a graph and subsequently prove properties thereof in zero-knowledge proofs of knowledge. While known to be expressive enough to encode statements from NP languages, one main use of graph signatures is in topology certification and confidentiality-preserving security assurance. In this paper, we present an efficient and provably secure graph signature scheme in the standard model with tight...

The boomerang and rectangle attacks are adaptions of differential cryptanalysis that regard the target cipher $E$ as a composition of two sub-ciphers, i.e., $E = E_{1}\circ E_{0}$, to construct a distinguisher for $E$ with probability $p^{2}q^{2}$ by concatenating two short differential trails for $E_{0}$ and $E_{1}$ with probability $p$ and $q$ respectively. According to the previous research, the dependency between these two differential characteristics has a great impact on the...

The connectivity is increasing in the world with the increased usage of IoT (Internet of Things) devices. To this end, amount of data that needs to be stored and retrieved securely has increased tremendously, but the IoT devices have a small amount of memory and computation capacity. Consequently, a storage area with a large amount of secured storage space is needed. Software-defined Networking (SDN) is an emerging network technology which implements a new paradigm of insecure applications...

The golden collision problem asks us to find a single, special collision among the outputs of a pseudorandom function. This generalizes meet-in-the-middle problems, and is thus applicable in many contexts, such as cryptanalysis of the NIST post-quantum candidate SIKE. The main quantum algorithms for this problem are memory-intensive, and the costs of quantum memory may be very high. The quantum circuit model implies a linear cost for random access, which annihilates the exponential...

End-user privacy in mobile telephony systems is nowadays of great interest because of the envisaged hyper-connectivity and the potential of the unprecedented services (virtual reality, machine-type communication, vehicle-to-everything, IoT, etc.) being offered by the new 5G system. This paper reviews the state of subscription privacy in 5G systems. As the work on 5G Release 15 -- the first full set of 5G standards -- has recently been completed, this seems to be an appropriate occasion for...

Given the inherent ad-hoc nature of popular communication platforms, out-of-band authenticated key-exchange protocols are becoming widely deployed: Key exchange protocols that enable users to detect man-in-the-middle attacks by manually authenticating one short value. In this work we put forward the notion of immediate key delivery for such protocols, requiring that even if some users participate in the protocol but do not complete it (e.g., due to losing data connectivity or to other common...

Given the links between nonlinearity properties and the related tables such as LAT, DDT, BCT and ACT that have appeared in the literature, the boomerang connectivity table BCT seems to be an outlier as it cannot be derived from the others using Walsh-Hadamard transform. In this paper, a brief unified summary of the existing links for general vectorial Boolean functions is given first and then a link between the autocorrelation and boomerang connectivity tables is established.

In order to study the resistance of a block cipher against boomerang attacks, a tool called the Boomerang Connectivity Table (BCT) for S-boxes was recently introduced. Very little is known today about the properties of this table especially for bijective S-boxes defined for $n$ variables with $n\equiv 0 \mod{4}$. In this work we study the boomerang uniformity of some popular constructions used for building large S-boxes, e.g. for 8 variables, from smaller ones. We show that the BCTs of all...

The boomerang attack, introduced by Wagner in 1999, is a cryptanalysis technique against block ciphers based on differential cryptanalysis. In particular it takes into consideration two differentials, one for the upper part of the cipher and one for the lower part, and it exploits the dependency of these two differentials. At Eurocrypt'18, Cid et al. introduced a new tool, called the Boomerang Connectivity Table (BCT) that permits to simplify this analysis. Next, Boura and Canteaut...

In Eurocrypt 2018, Cid et al. proposed a novel notion called the boomerang connectivity table, which formalised the switch property in the middle round of boomerang distinguishers in a unified approach. In this paper, we present a generic model of the boomerang connectivity table with automatic search technique for the first time, and search for (related-key) boomerang distinguishers directly by combining with the search of (related-key) differential characteristics. With the technique, we...

S-boxes are functions with an input so small that the simplest way to specify them is their lookup table (LUT). Unfortunately, some algorithm designers exploit this fact to avoid providing the algorithm used to generate said lookup table. In this paper, we provide tools for finding the hidden structure in an S-box or to identify it as the output of a complex generation process rather than a random sample. We introduce various "anomalies". These real numbers are such that a property with...

As of September 2019, Monero is the most capitalized privacy- preserving cryptocurrency, and is ranked tenth among all cryptocurren- cies. Monero’s on-chain data privacy guarantees, i.e., how mixins are selected in each transaction, have been extensively studied. However, de- spite Monero’s prominence, the network of peers running Monero clients has not been analyzed. Such analysis is of prime importance, since po- tential vulnerabilities in the peer-to-peer network may lead to attacks...

At Eurocrypt'18, Cid, Huang, Peyrin, Sasaki, and Song introduced a new tool called Boomerang Connectivity Table (BCT) for measuring the resistance of a block cipher against the boomerang attack which is an important cryptanalysis technique introduced by Wagner in 1999 against block ciphers. Next, Boura and Canteaut introduced an important parameter related to the BCT for cryptographic Sboxes called boomerang uniformity. The purpose of this paper is to present a brief state-of-the-art on the...

Differential cryptanalysis and linear cryptanalysis are the two best-known techniques for cryptanalysis of block ciphers. In 1994, Langford and Hellman introduced the differential-linear (DL) attack based on dividing the attacked cipher $E$ into two subciphers $E_0$ and $E_1$ and combining a differential characteristic for $E_0$ with a linear approximation for $E_1$ into an attack on the entire cipher $E$. The DL technique was used to mount the best known attacks against numerous ciphers,...

The importance of efficient MPC in today's world needs no retelling. An obvious barebones requirement to execute protocols for MPC is the ability of parties to communicate with each other. Traditionally, we solve this problem by assuming that every pair of parties in the network share a dedicated secure link that enables reliable message transmission. This assumption is clearly impractical as the number of nodes in the network grows, as it has today. In their seminal work, Dwork, Peleg,...

The boomerang attack is a variant of differential cryptanalysis which regards a block cipher $E$ as the composition of two sub-ciphers, i.e., $E=E_1\circ E_0$, and which constructs distinguishers for $E$ with probability $p^2q^2$ by combining differential trails for $E_0$ and $E_1$ with probability $p$ and $q$ respectively. However, the validity of this attack relies on the dependency between the two differential trails. Murphy has shown cases where probabilities calculated by $p^2q^2$ turn...

In EUROCRYPT 2018, Cid et al. introduced a new concept on the cryptographic property of S-boxes: Boomerang Connectivity Table (BCT for short) for evaluating the subtleties of boomerang-style attacks. Very recently, BCT and the boomerang uniformity, the maximum value in BCT, were further studied by Boura and Canteaut. Aiming at providing new insights, we show some new results about BCT and the boomerang uniformity of permutations in terms of theory and experiment in this paper. Firstly,...

In this paper, we describe Mobile CoWPI, a deployable, end-to-end secure mobile group messaging application with proofs of security. Mobile CoWPI allows dynamic groups of users to participate in, join, and leave private, authenticated conversations without requiring the participants to be simultaneously online or maintain reliable network connectivity. We identify the limitations of mobile messaging and how they affect conversational integrity and deniability. We define strong models of...

Increasingly connectivity becomes integrated in products and devices that previously operated in a stand-alone setting. This observation holds for many consumer ap- plications in the so-called "Internet of Things" (IoT) as well as for corresponding industry applications (IIoT), such as industrial process sensors. Often the only practicable means for authentication of human users is a password. The security of password-based authentication schemes frequently forms the weakest point of...

A boomerang attack is a cryptanalysis framework that regards a block cipher $E$ as the composition of two sub-ciphers $E_1\circ E_0$ and builds a particular characteristic for $E$ with probability $p^2q^2$ by combining differential characteristics for $E_0$ and $E_1$ with probability $p$ and $q$, respectively. Crucially the validity of this figure is under the assumption that the characteristics for $E_0$ and $E_1$ can be chosen independently. Indeed, Murphy has shown that independently...

Mix networks are a key technology to achieve network anonymity and private messaging, voting and database lookups. However, simple mix network designs are vulnerable to malicious mixes, which may drop or delay packets to facilitate traffic analysis attacks. Mix networks with provable robustness address this drawback through complex and expensive proofs of correct shuffling but come at a great cost and make limiting or unrealistic systems assumptions. We present Miranda, an efficient mix-net...

We present a certificate access management system to support the USDOT's proposed rule on Vehicle-to-Vehicle (V2V) communications, Federal Motor Vehicle Safety Standard (FMVSS) No.~150. Our proposal, which we call Binary Hash Tree based Certificate Access Management (BCAM) eliminates the need for vehicles to have bidirectional connectivity with the Security Credential Management System (SCMS) for certificate update. BCAM significantly improves the ability of the SCMS to manage large-scale...

Connectivity becomes increasingly important also for small embedded systems such as typically found in industrial control installations. More and more use-cases require secure remote user access increasingly incorporating handheld based human machine interfaces, using wireless links such as Bluetooth. Correspondingly secure operator authentication becomes of utmost importance. Unfortunately, often passwords with all their well-known pitfalls remain the only practical mechanism. We present an...

Within the next few years, billions of IoT devices will densely populate our cities. In this paper we describe a new type of threat in which adjacent IoT devices will infect each other with a worm that will spread explosively over large areas in a kind of nuclear chain reaction, provided that the density of compatible IoT devices exceeds a certain critical mass. In particular, we developed and verified such an infection using the popular Philips Hue smart lamps as a platform. The worm...

We are at the dawn of a hyper connectivity age otherwise known as the Internet of Things (IoT). It is widely accepted that to be able to reap all benefits from the IoT promise, device security will be of paramount importance. A key requirement for most security solutions is the ability to provide secure cryptographic key storage in a way that will easily scale in the IoT age. In this paper, we focus on providing such a solution based on Physical Unclonable Functions (PUFs). To this end,...

We consider secure two-party computation in the client-server model. In our scenario, two adversaries operate \emph{separately but simultaneously}, each of them corrupting one of the parties and a restricted subset of servers that they interact with. We model security in this setting via the local universal composability framework introduced by Canetti and Vald and show that information-theoretically secure two-party computation is possible if and only if there is always at least one server...

Key predistribution schemes for resource-constrained networks are methods for allocating symmetric keys to devices in such a way as to provide an efficient trade-off between key storage, connectivity and resilience. While there have been many suggested constructions for key predistribution schemes, a general understanding of the design principles on which to base such constructions is somewhat lacking. Indeed even the tools from which to develop such an understanding are currently limited,...

Digital signature schemes are a foundational cryptographic building block in certification and the projection of trust. Based on a signature scheme on committed graphs, we propose a toolkit of certification and proof methods to sign committed topology graphs and to prove properties of their certificates in zero-knowledge. This toolkit allows an issuer, such as an auditor, to sign the topology representation of an infrastructure. The prover, such as an infrastructure provider, can then...

Mission critical applications on homogenous mobile wireless sensor networks (HMWSNs) mandate new sets of security appliances to be friendly with existing resource constrained hardware platforms. To deliver a promising security, particularly in military deployments, mechanisms have to build upon an efficient key management that compensates HMWSNs constraints. Cluster-based key establishment is being the prime focus among the recent works in key establishment due to its significant improvement...

Technological advancements in cloud computing due to increased connectivity and exponentially proliferating data has resulted in migration towards cloud architecture. Cloud computing is technology where the users’ can use high end services in form of software that reside on different servers and access data from all over the world. Cloud storage enables users to access and store their data anywhere. It also ensures optimal usage of the available resources. There is no need for the user to...

Embedded computing devices (such as actuators, controllers and sensors of various sizes) increasingly permeate many aspects of modern life: from medical to automotive, from building and factory automation to weapons, from critical infrastructures to home entertainment. Despite their specialized nature as well as limited resources and connectivity, these devices are now becoming increasingly popular and attractive targets for various attacks, especially, remote malware infestations. There has...

In this paper there are considered several approaches for the increasing performance of software implementation of integer multiplication algorithm for the 32-bit & 64-bit platforms via parallelization. The main idea of algorithm parallelization consists in delayed carry mechanism using which authors have proposed earlier [11]. The delayed carry allows to get rid of connectivity in loop iterations for sums accumulation of products, which allows parallel execution of loops iterations in...

Tor is a widely used anonymity network providing low-latency communication capabilities. Around 400,000 users per day use Tor to route TCP traffic through a sequence of relays; three hops are selected from a pool of currently almost 3000 volunteer-operated Tor relays to comprise a route through the network for a limited time. In comparison to single-hop proxies, forwarding TCP streams through multiple relays increases the anonymity of the users significantly: each hop along the route only...

A commonly used metric for comparing the resilience of key predistribution schemes is $\fail_s$, which measures the proportion of network connections which are `broken' by an adversary which has compromised $s$ nodes. In `Random key predistribution schemes for sensor networks', Chan, Perrig and Song present a formula for measuring the resilience in a class of random key predistribution schemes called $q$-composite schemes. We present a correction to this formula for schemes where more than...

We consider secure multi-party computation (MPC) in a setting where the adversary can separately corrupt not only the parties (nodes) but also the communication channels (edges), and can furthermore choose selectively and adaptively which edges or nodes to corrupt. Note that if an adversary corrupts an edge, even if the two nodes that share that edge are honest, the adversary can control the link and thus deliver wrong messages to both players. We consider this question in the...

In this paper we give the minimal connectivity required in a synchronous directed network, which is under the influence of a computationally unbounded \emph{Byzantine} adversary that can corrupt a subset of nodes, so that Secure Message Transmission is possible between sender $S$ and receiver $R$. We also show that secure communication between a pair of nodes in a given synchronous directed network is possible in both directions if and only if reliable communication is possible between...

In this paper, we study the communication complexity of Reliable Message Transmission (RMT) and Secure Message Transmission (SMT) protocols in asynchronous settings. We consider two variants of the problem, namely perfect} (where no error is allowed in the protocol outcome) and statistical (where the protocol may output a wrong outcome with negligible probability). RMT and SMT protocols have been investigated rigorously in synchronous settings. But not too much attention has been paid to the...

Cichon, Golebiewski and Kutylowski (\cite{CGK}) proposed a technique for ``key redistribution'' in sensor networks. The idea is that long-term keys held by the sensor nodes are used to encrypt temporal keys that a base station then broadcasts to the network. The temporal keys are used as session keys by the nodes in the sensor network. It is argued that this provides increased connectivity and resilience as compared to a standard Eschenauer-Gligor key predistribution scheme, as well as...

We provide a design and implementation of self-protecting electronic medical records (EMRs) using attribute-based encryption. Our system allows healthcare organizations to export EMRs to storage locations outside of their trust boundary, including mobile devices, Regional Health Information Organizations (RHIOs), and cloud systems such as Google Health. In contrast to some previous approaches to this problem, our solution is designed to maintain EMR availability even when providers are...

For unconditionally reliable message transmission (URMT) in synchronous directed networks of n nodes, a subset of which may be Byzantine faulty, it is well-known that the minimum connectivity requirements for zero-error (perfect) protocols to exist is strictly higher than those where a negligible yet non-zero error probability is allowed (Monte Carlo protocols). In this work, we study the minimum connectivity requirements for the existence of (a) synchronous Las Vegas protocols, (b)...

In this paper, we suggest the idea of separately treating the connectivity and communication model of a Wireless Sensor Network(WSN). We then propose a novel connectivity model for a WSN using first order Reed-Muller Codes. While the model has a hierarchical structure, we have shown it works equally well for Distributed WSN. Though one can use any communication model, we prefer to use communication model suggested by Ruj and Roy [1] for all computations and results in our work. One might...

In the context of secure point-to-point message transmission in networks with minimal connectivity, previous studies showed that feedbacks from the receiver to the sender can be used to reduce the requirements of network connectivity. We observe that the way how feedbacks were used in previous work does not guarantee perfect privacy to the transmitted message, when the adversary performs a Guessing Attack. In this paper, we shall describe our new Guessing Attack to some existing protocols...

Recent emergence of RFID tags capable of performing public key operations motivates new RFID applications, including electronic travel documents, identification cards and payment instruments. In such settings, public key certificates form the cornerstone of the overall system security. In this paper, we argue that one of the prominent -and still woefully unaddressed- challenges is how to handle revocation checking of RFID reader certificates. This is an important issue considering that these...

We consider symmetric key predistribution in grid-based wireless sensor networks. Networks consisting of wireless sensor nodes arranged in a grid pattern have many useful applications, including environmental monitoring and agribusiness. The structured physical distribution of nodes in such networks facilitates efficient distribution of keys to the nodes prior to deployment. It has been shown that combinatorial objects known as distinct-difference configurations (DDCs) can be used to...

The aim of this paper is to demonstrate the feasibility of authenticated throughput-efficient routing in an unreliable and dynamically changing synchronous network in which the majority of malicious insiders try to destroy and alter messages or disrupt communication in any way. More specifically, in this paper we seek to answer the following question: Given a network in which the majority of nodes are controlled by a malicious adversary and whose topology is changing every round, is it...

Recent literature contains proposals for key predistribution schemes for sensor networks in which nodes are deployed in separate groups. In this paper we consider the implications of group deployment for the connectivity and resilience of a key predistribution scheme. After showing that there is a lack of flexibility in the parameters of a scheme due to Liu, Ning and Du, limiting its applicability in networks with small numbers of groups, we propose a more general scheme, based on the...

We consider the problem of probabilistic reliable communication (PRC) over synchronous networks modeled as directed graphs in the presence of a Byzantine adversary when players' knowledge of the network topology is not complete. We show that possibility of PRC is extremely sensitive to the changes in players' knowledge of the topology. This is in complete contrast with earlier known results on the possibility of perfectly reliable communication over undirected graphs where the case of each...

In this paper, we study the issues related to the possibility, feasibility and optimality for perfectly secure message transmission (PSMT) in an undirected synchronous network, under the influence of a mixed adversary having unbounded computing power, who can corrupt some of the nodes in the network in Byzantine, fail-stop and passive fashion respectively. Specifically, we answer the following questions: (a) Possibility: Given a network and a mixed adversary, what are the necessary and...

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...

We study the problem of Perfectly Reliable Message Transmission}(PRMT) and Perfectly Secure Message Transmission (PSMT) between two nodes S and R in an undirected synchronous network, a part of which is under the influence of an all powerful mobile Byzantine adversary. In ACISP 2007 Srinathan et. al. has proved that the connectivity requirement for PSMT protocols is same for both static and mobile adversary thus showing that mobility of the adversary has no effect on the possibility of PSMT...

Secure multi-party computation (MPC) is a central problem in cryptography. Unfortunately, it is well known that MPC is possible if and only if the underlying communication network has very large connectivity---specifically, $\Omega(t)$, where $t$ is the number of potential corruptions in the network. This impossibility result renders existing MPC results far less applicable in practice, since most deployed networks have in fact a very small degree. In this paper, we show how to circumvent...

Secure multiparty computation of a multivariate function is a central problem in cryptography. It is known that secure multiparty computation can be realized by a set of $n$ parties iff the connectivity of the underlying (authenticated) communication network is more than twice the number of corrupted parties. This impossibility result makes secure multiparty computation far less applicable in practice, as most deployed networks have a much lower degree than $O(n)$ and one would ideally like...

With respect to a special class of access structures based on connectivity of graphs, we start from a linear secret sharing scheme and turn it into a secret sharing scheme with perfect security and exponentially small error probability by randomizing the reconstruction algorithm through random walks on graphs. It reduces the polynomial work space to logarithmic. Then we build the corresponding statistical multiparty computation protocol by using the secret sharing scheme. The results of this...

In this paper, we contribute the construction of practical perfect multiparty computation protocols based on the connectivity of graphs.

Achieving secure communications in networks has been one of the most important problems in information technology. Dolev, Dwork, Waarts, and Yung have studied secure message transmission in one-way or two-way channels. They only consider the case when all channels are two-way or all channels are one-way. Goldreich, Goldwasser, and Linial, Franklin and Yung, Franklin and Wright, and Wang and Desmedt have studied secure communication and secure computation in multi-recipient...