The distributed ledger technology first introduced as a baseline technology for Bitcoin is disrupting many fields with its features of immutability and traceability. Applying blockchain in different fields is not one size fits for all solution. The various domains came up with different drawbacks of blockchain. To resolve these problems changes in block structures and consensus mechanisms of blockchain are proposed and used for different use cases or domains. We have proposed a consensus mechanism to reduce latency and increase the throughput of transactions processed by the blockchain network. The evaluation of the newly proposed consensus mechanism is done using queuing theory, mathematical models or simulations. Beyond this, we have used the Hyperledger platform to implement our proposed consensus mechanism Proof of Scope. The performance of implementations of Raft and PoW-Ethash consensus mechanisms from Hyperledger are evaluated with the proposed consensus mechanism. The varying load was applied to the network to measure transaction throughput. It is found that the latency is lower and throughput is better of the proposed consensus mechanism than that of Raft and PoW-Ethash for the same network conditions.
Sai Sleghana Bala, Bhavya Prasad, Anjali Maruti Jadhav, Kumud Wasnik
This paper discusses how blockchain (Ethereum) can be used to as a solution to improve or mitigate communication and storage issues of healthcare information. Smart hospital functionality of drug tracing has been achieved using the non-replicable feature offered by non-fungible tokens (NFTs) generated by ERC721. Every manufacturer along with the medicines allotted to the distributer are treated as unique entities which cannot be replicated. All entity details are recorded in SQL databases. Registration of a patient with the insurance claim system, assigns a unique ID using Secure Hash Algorithm 256 (SHA256) improving security.
The problem of Byzantine Fault Tolerance (BFT) has received a lot of attention in the last 30 years. Due to the popularity of Proof of Stake (PoS) blockchains in recent years, several BFT protocols have been deployed in the large scale of Internet environment. We analyze several popular BFT protocols such as Capser FFG/CBC-FBC for Ethereum 2.0 and GRANDPA for Polkadot. Our analysis shows that the security models for these BFT protocols are slightly different from the models commonly accepted in the academic literature. For example, we show that, if the adversary has a full control of the message delivery order in the underlying network, then none of the BFT protocols for Ethereum blockchain 2.0 and Polkadot blockchain could achieve liveness even in a synchronized network. Though it is not clear whether a practical adversary could actually control and re-order the underlying message delivery system (at Internet scale) to mount these attacks, it raises an interesting question on security model gaps between academic BFT protocols and deployed BFT protocols in the Internet scale. With these analysis, this article proposes a Casper CBC-FBC style binary BFT protocol and shows its security in the traditional academic security model with complete asynchronous networks. For partial synchronous networks, we propose a multi-value BFT protocol BDLS based on the seminal DLS protocol and show that it is one of the most efficient practical BFT protocols at large scale networks in the traditional academic BFT security model. The implementation of BDLS is available at https://github.com/yonggewang/bdls . Finally, we propose a multi-value BFT protocol XP for complete asynchronous networks and show its security in the traditional academic BFT security model.
Francesco D’Amato, Joachim Neu, Ertem Nusret Tas, David Tse
The LMD GHOST consensus protocol is a critical component of proof-of-stake Ethereum. In its current form, this protocol is brittle, as evidenced by recent attacks and patching attempts. We propose Goldfish, a new protocol that satisfies key properties required of a drop-in replacement for LMD GHOST: Goldfish is secure in the sleepy model, assuming a majority of the validators follows the protocol. Goldfish is reorg resilient so that honestly produced blocks are guaranteed inclusion in the ledger, and it supports fast confirmation with expected confirmation latency independent of the desired security level. Subsampling validators can improve the communication efficiency of Goldfish, and Goldfish is composable with finality/accountability gadgets. Crucially, Goldfish is structurally similar to LMD GHOST, providing a credible path to adoption in Ethereum. Attacks on LMD GHOST exploit lack of coordination among honest validators, typically provided by a locking mechanism in classical BFT protocols. However, locking requires votes from a quorum of all participants and is not compatible with fluctuating participation. Goldfish is powered by a novel coordination mechanism to synchronize the honest validators' actions. Experiments with our prototype implementation of Goldfish suggest practicality.
Byzantine Fault-Tolerant (BFT) protocols are classical algorithms that offer a faster and more energy-efficient consensus mechanism compared to Proof-of-Work (PoW), which is typically used by cryptocurrencies such as Bitcoin. Synchronous BFT systems are hard to implement and vulnerable to attacks that aim to disrupt the synchrony of the system. Practical BFT (PBFT), which is a partially synchronous protocol, is a high-performance consensus algorithm that provides strong safety in the presence of a bounded number of faulty participants. Hotstuff is one such partially synchronous BFT State Machine Replication (SMR) protocol that aims to address the aforementioned issues. PBFT is becoming a popular choice for blockchain consensus, especially in permissioned systems (e.g. Ripple, Stellar, etc). However, it is not well understood how Hotstuff, and PBFT consensus in general, behave under varying conditions that are commonly found in blockchain networks. In this paper, we present a theoretical model for the Hotstuff consensus mechanism which accurately predicts blockchain-related metrics such as the transaction throughput and expected confirmation time using important networking parameters such as the number of replicas, link latency, and packet loss. Furthermore, we validate our model through extensive simulations carried out using OMNeT++. Our results show that Hotstuff performance degrades drastically when the number of replicas increases. We observe that with a maximum number of tolerable faulty nodes, when the number of validators is increased to 127, throughput tends to zero. As well, packet loss ratio and transaction processing time are two other factors that significantly affect the performance of Hotstuff.
Tatjana Davidović, Milan Todorovic, Dušan Ramljak, Tatjana Jakšić Krüger · 7 authors
We propose Combinatorial Optimization based Consensus Protocol (COCP) that considers efficient use of energy in Blockchain (BC) consensus protocol based on Proof-of-Useful-Work (PoUW) concept. Instead of classical cryptographic puzle, it involves dealing with hard real-life combinatorial optimization (CO) problems submitted by BC participants called customers. Two sources of rewards are provided for miners, one related to adding a new block and the other for solving an instance of CO problem. The main issues that arise when combining BC and CO, are security and consistency of maintaining the whole system. We discuss how to resolve them and what are the benefits of the proposed COCP for all BC participants. Our proposed doubly-rewarding scheme and efficiency in energy exploration are illustrated on a small example from the Ethereum BC network.
Blockchain has found many applications, apart from Bitcoin, in different fields and it has the potential to be very useful in the satellite communications and space industries. Decentralized and secure protocols for processing and manipulating space transactions of satellite swarms in the form of Space Digital Tokens (SDT) can be built using blockchain technology. Tokenizing space transactions using SDTs will open the door to different new blockchain-based solutions for the advancement of constellation-based satellite communications in the space industry. Developing blockchain solutions using smart contracts could be used in securely authenticating various P2P satellite communications and transactions within/between satellite swarms. To manage and secure these transactions, using the proposed SDT concept, this paper suggested a blockchain-based protocol called Proof of Space Transactions (PoST). This protocol was adopted to manage and authenticate the transactions of satellite constellations in a P2P connection. The PoST protocol was prototyped using the Ethereum blockchain and experimented with to evaluate its performance using four metrics: read latency, read throughput, transaction latency, and transaction throughput. The simulation results clarified the efficiency of the proposed PoST protocol in processing and verifying satellite transactions in a short time according to read and transaction latency results. Moreover, the security results showed that the proposed PoST protocol is secure and efficient in verifying satellite transactions according to true positive rate (TPR), true negative rate (TNR), and accuracy metrics. These findings may shape a real attempt to develop a new generation of Blockchain-based satellite constellation systems.
The properties of decentralization, security, and immutability have made the blockchain technology beneficial for various Internet of Things (IoT) applications. Consensus algorithms enable the peers in IoT-based networks to reach a common agreement on the current state of the network stored in a distributed ledger. The consensus protocols such as Proof of Work (PoW) and Proof of Stake (PoS) face centrality failure problem in terms of high concentration of computational power and the amount of tokens respectively. Thus, the scope exists to enhance the existing consensus protocols and address the centralization problem maintaining low complexity and resource consumption. We propose a novel consensus protocol based on Proof of Work (PoW) and Proof of Stake (PoS). We name our proposed consensus protocol as Proof of SCore (PoSC). PoSC provides fairness in decentralized network by calculating the combination score from all the nodes. This combination score relates to the stake and reputation score. This score helps the IoT nodes to maintain trust and ensure security. We have also performed the experimental and logical interpretation of PoSC. We compare the performance of PoSC with the existing consensus protocols including PoW, PoS, Byzantine Fault Tolerance, Raft, and Paxos. Our proposed PoSC protocol is efficient in terms of reduced memory consumption by 35%, reduced time consumption by 30%, and energy consumption reduction by 25% as compared to the mentioned existing protocols on average. Moreover, PoSC avoids centrality failure suffered by PoW and PoS. Thus, PoSC is suitable for resource constrained applications of IoTs.
While it is possible to exchange tokens whose smart contracts are on the same blockchain, cross-exchanging bitcoins for a Bitcoin wrapped token is still cumbersome. In particular, current methods of exchange are still custodial and perform privacy-threatening controls on the users in order to operate. To solve this problem we present BxTB: cross-chain exchanges of bitcoins for any Bitcoin wrapped tokens. BxTB lets users achieve that by bypassing the mint-and-burn paradigm of current wrapped tokens and cross-exchanging already minted tokens in a P2P way. Instead of relaying on HTLCs and the overhead of communication and slowness due to time-locks, we leverage Stateless SPVs, i.e. proof-of-inclusion of transactions in the Bitcoin chain validated through a smart contract deployed on the other blockchain. Furthermore, since this primitive has not been introduced in the academic literature yet, we formally introduce it and we prove its security.
Distributed systems play a central role in modern computing, providing scalability, reliability, and fault tolerance. However, ensuring data availability in such systems remains a critical challenge, particularly in the face of attacks like data corruption, denial-of-service, and data loss. Cryptographic techniques can play a pivotal role in securing the availability of data by ensuring both data integrity and access control. This paper explores various cryptographic mechanisms, including hash functions, digital signatures, and distributed ledger technologies like blockchain, to enhance the reliability and availability of data in distributed systems. The study also discusses challenges in implementing these techniques in large-scale distributed environments and suggests strategies for future improvements
Farhad Keramat, Jorge Peña Queralta, Tomi Westerlund
With the increasing ubiquity of autonomous robotic solutions, the interest in their connectivity and in the cooperation within multi-robot systems is rising. Two aspects that are a matter of current research are robot security and secure multi-robot collaboration robust to byzantine agents. Blockchain and other distributed ledger technologies (DLTs) have been proposed to address the challenges in both domains. Nonetheless, some key challenges include scalability and deployment within real-world networks. This paper presents an approach to integrating IOTA and ROS 2 for more scalable DLT-based robotic systems while allowing for network partition tolerance after deployment. This is, to the best of our knowledge, the first implementation of IOTA smart contracts for robotic systems, and the first integrated design with ROS 2. This is in comparison to the vast majority of the literature which relies on Ethereum. We present a general IOTA+ROS 2 architecture leading to partition-tolerant decision-making processes that also inherit byzantine tolerance properties from the embedded blockchain structures. We demonstrate the effectiveness of the proposed framework for a cooperative mapping application in a system with intermittent network connectivity. We show both superior performance with respect to Ethereum in the presence of network partitions, and a low impact in terms of computational resource utilization. These results open the path for wider integration of blockchain solutions in distributed robotic systems with less stringent connectivity and computational requirements.
Various techniques are used to develop the Blockchain Technology. It is a technology which is designed in such a way that it is impossible to hack the system or hammer out the data stored in it It is one of the leading technologies in the current scenario. The goal of blockchain is to allow digital information to be recorded and distributed, but not edited. In this way, a blockchain is as the basis for absolute registry, or transactional records that cannot be changed, deleted, or otherwise disposed. Different domains are being adapting the blockchain technology which brings up the peer-to-peer connections and the cost of the middlemen is reduced. The technology uses authentication to secure the data and make it impossible to break than any legacy system [2].
Ambre Toulemonde, Loic Besson, Louis Goubin, Jacques Patarin
The blockchain is a new technology that attracts several actors since 2009, and in particular in the financial domain with the emergence of cryptocurrencies such as the well-known Bitcoin. In a blockchain, seen also as a distributed ledger or a chain of blocks, the participants use a consensus protocol to add new data into the ledger. For example, in the Bitcoin Proof-of-Work consensus protocol, the participants have to unnecessarily invest a huge amount of energy to add a new block of transactions, and therefore to also win the coin associated to this block. Several consensus protocols have been proposed to overcome this waste and resource intensive process. In this paper, we present a new consensus protocol for blockchain technologies called Useful Work (UW). Our UW protocol is based on the Proof-of-Stake and Proof-of-Work mechanisms where the computing work is dedicated to useful problems. The participants get a chance to win coins after performing honest and useful work for a submitted problem. We present a high-level description of our UW protocol that is configurable and propose some variants of the protocol. We discuss also some new and well-known issues that our protocol prevents.
In blockchain, the consensus algorithm is a core component that governs the trust among the participants in the blockchain activities. However, the exiting consensus algorithms suffer from performance bottleneck such as low throughput, high delay, unstable performance, sustainability issues and vulnerability to targeted attacks. In this paper, we propose a new consortium blockchain consensus algorithm, referred to as Weighted Byzantine Fault Tolerance (WBFT) consensus algorithm that improves system throughput and consensus delay. We introduce a dynamic weighting mechanism for consensus nodes, which enhances the security of blockchain system by weakening the influence of malicious nodes and reduces the probability of malicious behavior. We validate the performance of WBFT experimentally and compare it against Practical Byzantine Fault Tolerance (PBFT) and Reputation-Based Byzantine Fault-Tolerance (RBFT) based approaches. The results show that WBFT substantially outperforms PBFT and RBFT in terms of system throughput, consensus delay and security.
In the race toward next-generation systems of systems, the adoption of edge and cloud computing is escalating to deliver the underpinning end-to-end services. To safeguard the increasing attack landscape, remote attestation lets a verifier reason about the state of an untrusted remote prover. However, for most schemes, verifiability is only established under the omniscient and trusted verifier assumption, where a verifier knows the prover’s trusted states, and the prover must reveal evidence about its current state. This assumption severely challenges upscaling, inherently limits eligible verifiers, and naturally prohibits adoption in public-facing security-critical networks. To meet current zero trust paradigms, we propose a general ZEro-Knowledge pRoof of cOnformance (ZEKRO) scheme, which considers mutually distrusting participants and enables a prover to convince an untrusted verifier about its state’s correctness in zero-knowledge, i.e., without revealing anything about its state.
Limited scalability and transaction costs are, among others, some of the critical issues that hamper a wider adoption of distributed ledger technologies (DLT). That is particularly true for the Ethereum blockchain, which, so far, has been the ecosystem with the highest adoption rate. Quite a few solutions, especially on the Ethereum side of things, have been attempted in the last few years. Most of them adopt the approach to offload transactions from the blockchain mainnet, a.k.a. Level 1 (L1), to a separate network. Such systems are collectively known as Level 2 (L2) systems. While mitigating the scalability issue, the adoption of L2 introduces additional drawbacks: users have to trust that the L2 system has correctly performed transactions or, conversely, high computational power is required to prove transactions correctness. In addition, significant technical knowledge is needed to set up and manage such an L2 system. To tackle such limitations, we propose 1DLT: a novel system that enables rapid and trustless deployment of an Ethereum Virtual Machine based blockchain that overcomes those drawbacks.
Norine Coenen, Bernd Finkbeiner, Jana Hofmann, Julia Tillman
Smart contracts are small but highly security-critical programs that implement wallets, token systems, auctions, crowd funding systems, elections, and other multi-party transactions on the blockchain. A broad range of methods has been developed to ensure that a smart contract is functionally correct. However, smart contracts often additionally need to satisfy certain hyperproperties, such as symmetry, determinism, or an information flow policy. In this paper, we show how a synthesis method for smart contracts can ensure that the contract satisfies its desired hyperproperties. We build on top of a recently developed synthesis approach from specifications in the temporal logic TSL. We present HyperTSL, an extension of TSL for the specification of hyperproperties of infinite-state software. As a preprocessing step, we show how to detect if a hyperproperty has an equivalent formulation as a (simpler) trace property. Finally, we describe how to refine a synthesized contract to adhere to its HyperTSL specification.
James Lembke, Srivatsan Ravi, Pierre-Louis Roman, Patrick Eugster
Software-defined wide area networking (SD-WAN) enables dynamic network policy control over a large distributed network via network updates . To be practical, network updates must be consistent (i.e., free of transient errors caused by updates to multiple switches), secure (i.e., only be executed when sent from valid controllers), and reliable (i.e., function despite the presence of faulty or malicious members in the control plane), while imposing only minimal overhead on controllers and switches. We present SERENE: a protocol for se cure and re liable ne twork updates for SD-WAN environments. In short: Consistency is provided through the combination of an update scheduler and a distributed transactional protocol. Security is preserved by authenticating network events and updates, the latter with an adaptive threshold cryptographic scheme. Reliability is provided by replicating the control plane and making it resilient to a dynamic adversary by using a distributed ledger as a controller failure detector. We ensure practicality by providing a mechanism for scalability through the definition of independent network domains and exploiting the parallelism of network updates both within and across domains. We formally define SERENE’s protocol and prove its safety with regards to event-linearizability. Extensive experiments show that SERENE imposes minimal switch burden and scales to large networks running multiple network applications all requiring concurrent network updates, imposing at worst a 16% overhead on short-lived flow completion and negligible overhead on anticipated normal workloads.
Recently emerging Decentralized Finance (DeFi) transforms traditional financial products into trustless and transparent protocols. However, these protocols often require real-time external price information, and in this respect an entity named oracle is proposed-a third party reporting the prices from real-world sources to the blockchain. Unfortunately, current oracle designs lack transparency, compatibility and accountability (e.g., report deviations and operational failures/anomalies). Further-more, they merely include economic rewards without fine-grained financial penalties. To address these problems, we present BANC, the first transparent incentive protocol that aims at accountability and compatibility for DeFi price oracles. BANC requires oracles to transparently declare a manifest such that their obligations can be provably examined by authorized punishers. With a fair dispute-resolution protocol, BANC enables compliant oracles to invoke self-justifications, which can be resolved by a watchtower consortium securely and efficiently. BANC is designed to enhance operational accountability of DeFi oracles, and can be compatible with most DeFi platforms at low cost. We fully implement BANC to evaluate its efficiency.
Hari Kishore Chaparala, Sai Vineeth Doddala, Ahmad Showail, Abhishek Singh · 6 authors
The Non-fungible token (NFT) market has been booming with some reports estimating the surge in the market value to over 80 Billion USD in 2025. With this surge, comes the challenge of scaling NFT transactions and providing low latency responses to end-users. Exclusive layer-1 blockchains like Bitcoin and Ethereum which focus more on security and traceability are not suitable for high throughput NFT transactions of low value due to high gas fees. Layer-2 solutions can scale but have a trade-off of losing some strong decentralization and security guarantees offered by the Mainnet. In this paper, we propose LiftChain, a multi-stage NFT transaction protocol that can scale for high volume NFT transactions and at the same time inherit the security guarantees from Mainnet. LiftChain differs from existing NFT transaction protocols in that it allows multiple NFT transactions in the off-chain before becoming consistent with the on-chain. LiftChain also uses batching for gas fee savings and better bandwidth utilization. Our evaluations show that LiftChain provides comparable performance to baseline off-chain and with batching we see more than a 5-fold improvement in gas fee savings.
In a Proof of Stake (PoS) blockchain, all nodes need to be able to recognize approximately synchronized clocks. A PoS blockchain relies on external clocks, and each node synchronizes its local clock according to an external clock using Network Time Protocol (NTP) or a similar protocol. However, this external dependence is undesirable because it reduces the autonomy, sustainability and trustless nature of the blockchain. This paper presents a clock synchronization protocol for slot-based PoS blockchains. The proposed protocol estimates the block propagation time to ensure that the synchronization is closer to that of a real-world clock. In addition, the proposed method considers the clock drift and clock adjustment frequency to achieve more accurate synchronization. Simulation experiments show that the proposed method can synchronize with a time that is closer to that of a real-world clock and with higher accuracy than existing methods.
To guarantee delivery of their intended functionalities in the presence of unresponsive parties, current smart-contracts cut users off from being able to commit their responses after a fixed period of time has elapsed. However, current blockchains have limited transaction processing capacities, so a fixed amount of time will not always be sufficient to receive every critical transaction (C-TX). This paper presents a mechanism for adaptive cutoffs (ACs) which ensures that users retain the opportunity to commit C-TXs despite blockchain congestion, and enables early cutoffs when the number of required C-TXs is low. A non-interactive argument system for setting adaptive cutoffs under the current Ethereum Virtual Machine is described. Additionally, disputable cutoffs (DCs) are presented, which are a more efficient approach used in parallel to ACs based on a bisection-based dispute. Furthermore, it’s empirically demonstrated that an AC/DC-enabled smart-contract can receive a larger number of C-TXs than its non-adaptive counterparts when user responsiveness is slowed due to denial of service or congestion.
Due to its minimal energy requirement the PoS consensus protocol has become an attractive alternative to PoW in modern cryptocurrencies. In this protocol the chance of being selected as a block proposer in each round is proportional to the current stake of any node. Thus, nodes with higher stakes will achieve more block rewards, resulting in the so-called rich-getting-richer problem. In this paper, we introduce a new block reward mechanism called the FRD (Fair Reward Distribution) mechanism, in which for each block produced, in addition to a major reward given to the block proposer, a small reward is given to all other nodes. We prove that this reward mechanism makes the PoS protocol fairer in terms of concentration of wealth by developing on the Bagchi-Pal urn model.