Payment channel networks (PCNs) enhance the scalability of blockchains by allowing parties to conduct transactions off-chain, i.e, without broadcasting every transaction to all blockchain participants. To conduct transactions, a sender and a receiver can either establish a direct payment channel with a funding blockchain transaction or leverage existing channels in a multi-hop payment. The security of PCNs usually relies on the synchrony of the underlying blockchain, i.e., evidence of misbehavior needs to be published on the blockchain within a time limit. Alternative payment channel proposals that do not require blockchain synchrony rely on quorum certificates and use a committee to register the transactions of a channel. However, these proposals do not support multi-hop payments, a limitation we aim to overcome. In this paper, we demonstrate that it is in fact impossible to design a multi-hop payment protocol with both network asynchrony and faulty channels, i.e., channels that may not correctly follow the protocol. We then detail two committee-based multi-hop payment protocols that respectively assume synchronous communications and possibly faulty channels, or asynchronous communication and correct channels. The first protocol relies on possibly faulty committees instead of the blockchain to resolve channel disputes, and enforces privacy properties within a synchronous network. The second one relies on committees that contain at most f faulty members out of 3f+1 and successively delegate to each other the role of eventually completing a multi-hop payment. We show that both protocols satisfy the security requirements of a multi-hop payment and compare their communication complexity and latency.
In this paper, we present a simulation study of a Proof of Stake (PoS) consensus algorithm used in a public blockchain called Nxt. We first provide an overview of Nxt and its PoS consensus algorithm design, and introduce a concise mathematical analysis of the Nxt PoS algorithm. We then present an experimental study on the Nxt PoS behavior in a simulated environment and in a small network running Nxt private nodes. We show that the fractions of the blocks generated by forgers in the system are generally proportional to their weight in stakes provided that the weight is relatively small, which is consistent with the mathematical analysis. We consider two scenarios of double-spending attacks: (1) a single dominating forger with large stakes; and (2) a group of colluding forgers that collectively control large stakes. The simulation results show that the single-forger attack is more advantageous over using a pool of forgers in launching successful double-spending attacks. Finally, we propose a quota-based mechanism to limit the fraction of blocks that any forger could generate. We show that the mechanism is highly effective in mitigating the single-forger attack, but has limited success in preventing the double-spending attacks based on forging pools.
Servio Palacios, Aaron Ault, James V. Krogmeier, Bharat Bhargava · 5 authors
This paper introduces AGAPECert, an Auditable, Generalized, Automated, Privacy-Enabling, Certification framework capable of performing auditable computation on private data and reporting real-time aggregate certification status without disclosing underlying private data. AGAPECert utilizes a novel mix of trusted execution environments, blockchain technologies, and a real-time graph-based API standard to provide automated, oblivious, and auditable certification. Our technique allows a privacy-conscious data owner to run pre-approved Oblivious Smart Contract code in their own environment on their own private data to produce Private Automated Certifications. These certifications are verifiable, purely functional transformations of the available data, enabling a third party to trust that the private data must have the necessary properties to produce the resulting certification. Recently, a multitude of solutions for certification and traceability in supply chains have been proposed. These often suffer from significant privacy issues because they tend to take a" shared, replicated database" approach: every node in the network has access to a copy of all relevant data and contract code to guarantee the integrity and reach consensus, even in the presence of malicious nodes. In these contexts of certifications that require global coordination, AGAPECert can include a blockchain to guarantee ordering of events, while keeping a core privacy model where private data is not shared outside of the data owner's own platform. AGAPECert contributes an open-source certification framework that can be adopted in any regulated environment to keep sensitive data private while enabling a trusted automated workflow.
Nathalie Bertrand, Vincent Gramoli, Igor Konnov, Marijana Lazić · 6 authors
Today, the market capitalization of the seminal blockchain, Bitcoin, is about $803B which incentivizes malicious participants to find problematic executions that would allow them to steal financial assets. As the blockchain requires a distributed set of machines to agree on a unique block of transactions to be appended to the chain, attackers naturally try to exploit consensus vulnerabilities to double spend. As a result, formally verifying that a blockchain consensus protocol is safe and live is key to mitigate financial losses. Recent progress in mechanical proofs represent the first steps towards verifying blockchain consensus. The parameterized model checking of threshold automata (TAs) has recently proved instrumental in verifying fully asynchronous parts of consensus algorithms, like broadcast algorithms [4]. The aforementioned reduction technique cannot apply to partial synchrony: moving the message reception step to a later point in the execution might violate an assumed message delay.
Ertem Nusret Tas, David Tse, Fangyu Gai, Sreeram Kannan · 6 authors
Bitcoin is the most secure blockchain in the world, supported by the immense hash power of its Proof-of-Work miners. Proof-of-Stake chains are energy-efficient, have fast finality but face several security issues: susceptibility to non-slashable long-range safety attacks, low liveness resilience and difficulty to bootstrap from low token valuation. We show that these security issues are inherent in any PoS chain without an external trusted source, and propose a new protocol, Babylon, where an off-the-shelf PoS protocol checkpoints onto Bitcoin to resolve these issues. An impossibility result justifies the optimality of Babylon. A use case of Babylon is to reduce the stake withdrawal delay: our experimental results show that this delay can be reduced from weeks in existing PoS chains to less than 5 hours using Babylon, at a transaction cost of less than 10K USD per annum for posting the checkpoints onto Bitcoin.
Marco Benedetti, Francesco De Sclavis, Marco Favorito, Giuseppe Galano · 7 authors
Distributed Ledger Technologies (DLTs), when managed by a few trusted validators, require most but not all of the machinery available in public DLTs. In this work, we explore one possible way to profit from this state of affairs. We devise a combination of a modified Practical Byzantine Fault Tolerant (PBFT) protocol and a revised Flexible Round-Optimized Schnorr Threshold Signatures (FROST) scheme, and then we inject the resulting proof-of-authority consensus algorithm into Bitcoin (chosen for the reliability, openness, and liveliness it brings in), replacing its PoW machinery. The combined protocol may operate as a modern, safe foundation for digital payment systems and Central Bank Digital Currencies (CBDC).
This perspective highlights some recent progress on the research of Byzantine fault tolerant (BFT) consensus protocol in the era of blockchains, including both partially synchronous BFT and asynchronous BFT protocols, their fundamental building blocks, and their variants.
Blockchain is an innovative application of distributed storage, consensus algorithm, encryption algorithm, and other computer technologies. The consensus algorithm is the key to keep consistent among blockchain nodes. In most existing consensus algorithms, the leader node is responsible for proposing new block and communicating with other nodes. The leader node is easy to be the target of malicious attackers. With the increase of the number of nodes, the throughput and scalability of the blockchain system are also unsatisfactory. To address such issues, we propose the AnonymousFox consensus algorithm, which is suitable for the consortium blockchain and private blockchain. First, we design an anonymous leader node sorting algorithm, which hides the identity of the leader node through a variety of encryption algorithms. It periodically changes the ordered leader list to hide the target of malicious attackers. In addition, we design a consensus algorithm based on the anonymous identity of the leader node. Through one-to-many message communication, the amount of messages is greatly reduced. The complexity of the algorithm is$O(n)$. It solves the problem of ordered replication of state machines when the leader node is anonymous. We analyze the algorithm, it ensures safety and liveness when the fault nodes are less than one-third of the total. We evaluate the throughput, latency, scalability, resource consumption, exception processing, smart contract, and blockchain network through experiments. The throughput of the proposed algorithm is 49.3% higher than that of the practical Byzantine fault tolerance (PBFT) algorithm. The experimental results show that the proposed algorithm has high performance and scalability.
Iako je robustan i siguran, Proof of Work mehanizam konsenzusa suočava se s izazovima poput skalabilnosti, centralizacije, dostupnosti te negativnog utjecaja na okoliš. Samim time pojavila se potreba za alternativnim metodama konsenzusa. Proof of Stake i njegove varijacije nameću se kao rješenje. Konsenzusi obrađeni u radu su redom: Proof of Stake, Proof of Activity, Delegated Proof of Stake, Proof of Authority, Pure Proof of Stake te Proof of History. Svaki od navedenih pokušava, uz dodatne tehnologije razvijene oko mehanizma, riješiti probleme Proof of Work konsenzusa. Pojavom PoS konsenzusa i njegovih varijacija povećana je dostupnost za pojedinca da se uključi u rad mreže. Potrošnja energije je uvelike smanjena i generira se manje elektroničkog otpada. Skalabilnost se poboljšala u odnosu na PoW. Centraliziranost je jedan od izazova gdje bi se u budućnosti mogao vidjeti najveći napredak. U praktičnom dijelu rada, istraživanjem Solana blockchaina zaključili smo da je poprilično centraliziran.
Cong Yue, Tien Tuan Anh Dinh, Zhongle Xie, Meihui Zhang · 7 authors
Verifiable ledger databases protect data history against malicious tampering. Existing systems, such as blockchains and certificate transparency, are based on transparency logs --- a simple abstraction allowing users to verify that a log maintained by an untrusted server is append-only. They expose a simple key-value interface without transactions. Building a practical database from transparency logs, on the other hand, remains a challenge. In this paper, we explore the design space of verifiable ledger databases along three dimensions: abstraction, threat model, and performance. We survey existing systems and identify their two limitations, namely, the lack of transaction support and the inferior efficiency. We then present GlassDB, a distributed database system that addresses these limitations under a practical threat model. GlassDB inherits the verifiability of transparency logs, but supports transactions and offers high performance. It extends a ledgerlike key-value store with a data structure for efficient proofs, and adds a concurrency control mechanism for transactions. GlassDB batches independent operations from concurrent transactions when updating the core data structures. In addition, we design a new benchmark for evaluating verifiable ledger databases, by extending YCSB and TPC-C benchmarks. Using this benchmark, we compare GlassDB against four baselines: reimplemented versions of three verifiable databases, and a verifiable map backed by a transparency log. Experimental results demonstrate that GlassDB is an efficient, transactional, and verifiable ledger database system.
Jiang Xiao, Shijie Zhang, Zhiwei Zhang, Bo Li · 6 authors
A Directed Acyclic Graph (DAG)-based blockchain with its inherent parallel structure can potentially significantly improve the throughput performance over conventional blockchains. Such a performance improvement can be further enhanced through concurrent transaction processing. This, however, brings new challenges in concurrency control design in that there is an increased number of concurrent reads and writes to the same address in a DAG-based blockchain, which leads to a considerable rise of potential conflicts. Therefore, one critical problem is how to effectively and efficiently detect and order conflicting transactions. In this work, for the first time, we aim to improve system throughput and processing latency by exploring the address dependencies among different transactions. We propose NEZHA, an efficient concurrency control scheme for DAG-based blockchains. Specifically, NEZHA intelligently constructs an address-based conflict graph (ACG) while incorporating address dependencies as edges to capture all conflicting transactions. To generate a total order between transactions, we propose a hierarchical sorting (HS) algorithm to derive sorting ranks of addresses based on the ACG and sort transactions on each address. Extensive experiments demonstrate that, even under high data contention, NEZHA can increase the throughput over the conventional conflict graph scheme by up to 8 ×, while decreasing the transaction processing latency up to 10 ×.
Blockchain is a decentralized distributed ledger database. Consensus protocol is the core protocol of blockchain to solve Byzantine agreement problem. To let all blockchain nodes reach an agreement, the most commonly used Byzantine consensus protocol are Practical Byzantine Fault Tolerance (PBFT) protocols. PBFT requires that the number of malicious nodes$t$is less than$n/3$($n$is the total number of nodes), while quantum ones can raise the upper bound from$n/3$to$n/2$. However, there is a problem with quantum Byzantine consensus protocols, that is, the lack of malicious-degree evaluation. When the primary and reporting nodes are malicious, the number of agreements rounds and communication overhead will be significantly increased. Thus, a prevention mechanism for quantum consensus protocols is proposed in this paper, which includes two measures to prevent (or constrain) the malicious behaviors: (1) The trust-value calculation method to judge the honesty of nodes, which adjust the value according to nodes' behaviors using our trust-value evaluation formula; (2) The dual signature method to verify the legitimacy of reporting messages, which requires two nodes to agree and sign a message. The security analysis shows that our prevention mechanism can effectively prevent malicious nodes from being the primary node and substantially reduce the false messages from dishonest nodes.
Mainstream cryptocurrencies, based on proof of work or stake, require paying miners for the capital-intensive execution of a consensus protocol, and hence are unsuitable as a foundation for capital-free digital communities and for the bootstrap of a grassroots digital society. We aim to adapt and adjust the concepts, tools and technologies developed by the cryptocurrencies ecosystem, together with related networking technologies, into a foundation for a healthy grassroots digital economy and society. In this context we present the design and proof-of-concept implementation of a self-sovereign digital agent (ssDA), as an essential building block for a grassroots digital economy and society. The ssDA serves as a party, on behalf of its sovereign—a person—in digital social contracts, which are smart contracts among vetted participants, who are its sovereign in that they jointly execute the contract with an egalitarian consensus protocol. Digital social contracts may realize social networks, sharing economy applications, social governance of a digital community, and more. The ssDA is a software application that allows a person to partake in multiple digital social contracts simultaneously. Participation in a contract can be realized by initiating it or by being invited to it. Extra confidence in the integrity of the data is achieved by each person maintaining a blockchain containing all the person’s transactions in all contracts.
Haoqian Zhang, Louis-Henri Merino, Vero Estrada-Galiñanes, Bryan Ford
Front-running, the practice of benefiting from advanced knowledge of pending transactions, has proliferated in the cryptocurrency space with the emergence of decentralized finance. Front-running causes devastating losses to honest participants—estimated at $280M each month—and endangers the fairness of the ecosystem. We present Flash Freezing Flash Boys (F3B), an architecture to address front-running attacks by relying on a commit-and-reveal scheme where the contents of a transaction are encrypted and later revealed by a decentralized secret-management committee (SMC) when the transaction has been committed by the underlying consensus layer. To maintain legacy compatibility, we design F3B to be agnostic to the underlying consensus algorithm and compatible with existing smart contracts. A preliminary exploration of F3B shows that with a secret-management committee consisting of 8 and 128 members, F3B presents between 0.1 and 2.2 seconds of transaction-processing latency, respectively.
Sharding is a promising way to achieve blockchain scalability, increasing the throughput by partitioning nodes into multiple smaller groups, splitting the workload. However, when tackling the increasingly important smart contracts, existing blockchain sharding protocols do not scale well. They usually require complex multi-round cross-shard consensus protocols for contract execution and extensive cross-shard communication during state transmission, mainly because that each shard stores and executes an isolated, disjoint subset of contracts. In this paper, we present Jenga, a novel sharding-based approach for efficient smart contract processing. Its main idea is to break the isolation between shards by orchestrating the logic storage, state storage, and execution of smart contracts. In Jenga, all shards share the logic for all contracts. Therefore, multiple contracts involved in a smart contract transaction can be executed together by the same shard within one round. Moreover, different shards store distinct states (named state shards), several "orthogonal" execution channels are established based on the state shards, where each channel overlaps with all shards. Each node simultaneously belongs to a shard and an "orthogonal" channel, different channels execute different contracts. Therefore, via the overlapped nodes, the contract states can be directly broadcast between the state shards and the execution channels without additional cross-shard communication. We implement Jenga and evaluation results show that it provides outstanding performance gains in terms of throughput and transaction confirmation latency.
For any distributed system, consensus plays a pivotal role in holding together the whole system. This is true not just for any blockchain (BC) peer-to-peer (P2P) Network but also for Cloud Computing where the Leader Election Problem is solved by the use of various consensus algorithms. No “one” consensus algorithm is universal or perfect. Depending upon the type of BC employed and the use case of the BC, there may be a consensus algorithm that would help the system reach optimum functioning without compromising the integrity of the system. While proof of work (PoW) [ 2 ] became the first Consensus Mechanism to be used in BC, there have been many consensus algorithms to date. These are mechanisms which help the P2P network of a BC arrive at a decision. The decision taken most often is who is going to add the next block on the BC. This decision is crucial because if there exists a malicious entity in the network who gets in charge of the chain, then it would be detrimental to the overall functioning of the network. The chapter discusses the following consensus algorithms-PoW [ 2 ], proof of stake, delegated proof of stake, Byzantine fault tolerance (BFT), Crash Fault Tolerance, Hashgraph Consensus Algorithm, Proof of Elapsed Time, and Proof of Authority (PoA). The pros of the consensus algorithms and main drawbacks against implementation such as low throughput and excessive consumption of bandwidth have been discussed as well. A comparative analysis of the aforementioned algorithms with a major focus on use cases has been done to help understand how such mechanisms may be used for designing solutions which surpass the initial application of cryptocurrency and delve into real-world solutions in the fields including but not limited to the Internet of Things (IoT) and big data.
Margarita Capretto, Martín Ceresa, Antonio Fernández Anta, Antonio Russo · 5 authors
Blockchain technologies are facing a scalability challenge, which must be overcome to guarantee a wider adoption of the technology. This scalability issue is mostly caused by the use of consensus algorithms to guarantee the total order of the chain of blocks (and of the operations within each block). However, total order is often overkilling, since important advanced applications of smart-contracts do not require a total order of all the operations. Hence, if a more relaxed partial order (instead of a total order) is allowed under certain safety conditions, a much higher scalability can be achieved. In this paper, we propose a distributed concurrent data type, called Setchain, that allows implementing this partial order and increases significantly blockchain scalability. A Setchain implements a grow-only set object whose elements are not totally ordered, unlike conventional blockchain operations. When convenient, the Setchain allows forcing a synchronization barrier that assigns permanently an epoch number to a subset of the latest elements added. With the Setchain, operations in the same epoch are not ordered, while operations in different epochs are. We present different Byzantine-tolerant implementations of Setchain, prove their correctness and report on an empirical evaluation of a direct implementation. Our results show that Setchain is orders of magnitude faster than consensus-based ledgers to implement grow-only sets with epoch synchronization. Since the Setchain barriers can be synchronized with block consolidation, Setchain objects can be used as a sidechain to implement many smart contract solutions with much faster operations than on basic blockchains.
Luciano Freitas de Souza, Andrei Tonkikh, Adda-Akram Bendoukha, Sara Tucci-Piergiovanni · 7 authors
In a single secret leader election protocol (SSLE), one of the system participants is chosen and, unless it decides to reveal itself, no other participant can identify it. SSLE has a great potential in protecting blockchain consensus protocols against denial of service (DoS) attacks. However, all existing solutions either make strong synchrony assumptions or have expiring registration, meaning that they require elected processes to re-register themselves before they can be re-elected again. This, in turn, prohibits the use of these SSLE protocols to elect leaders in partially-synchronous consensus protocols as there may be long periods of network instability when no new blocks are decided and, thus, no new registrations (or re-registrations) are possible. In this paper, we propose Homomorphic Sortition -- the first asynchronous SSLE protocol with non-expiring registration, making it the first solution compatible with partially-synchronous leader-based consensus protocols. Homomorphic Sortition relies on Threshold Fully Homomorphic Encryption (ThFHE) and is tailored to proof-of-stake (PoS) blockchains, with several important optimizations with respect to prior proposals. In particular, unlike most existing SSLE protocols, it works with arbitrary stake distributions and does not require a user with multiple coins to be registered multiple times. Our protocol is highly parallelizable and can be run completely off-chain after setup. Some blockchains require a sequence of rounds to have non-repeating leaders. We define a generalization of SSLE, called Secret Leader Permutation (SLP) in which the application can choose how many non-repeating leaders should be output in a sequence of rounds and we show how Homomorphic Sortition also solves this problem.
Distributed Ledger Technology is a powerful tool to support direct collaboration between organisations, without requiring full trust into a centralised infrastructure. By defining a program logic and access policies with smart contracts, all interactions are verified in the distributed network and the history of the data is recorded on the ledger. Blockchain implementations targeting enterprise use cases also provide means for private transactions, where the content of the transaction is only readable by authorized participants. Direct access to the ledger requires a node with reliable connection to the network and sufficient computational resources, which usually cannot be fulfilled with lightweight Internet of Things devices and mobile applications. We present an advanced system for accessing an enterprise Blockchain through dedicated gateway nodes, while preserving the functionality of private transactions. A hybrid approach is used to allow computation- and storage restricted clients to send private transactions through a central gateway, and use Light Ethereum Subprotocol to verify the data integrity based on proofs from distributed nodes. To increase the client-side security level, we introduce a dedicated Hardware Security Module for key management and efficient execution of the cryptographic primitives. A proof-of-concept implementation, using the Quorum Blockchain client and an extension for the Tessera transaction manager, validates the feasibility of the approach and can be used for further research in this field.
Focusing on the business alliance scenario in blockchains, this paper proposes a new consensus mechanism named proof of rest (PoR) and strong smart contracts. The block structure and logic of PoR consensus are described. And a consortium blockchain system supporting strong smart contracts is designed. We modify the difficulty value algorithm based on proof of work (PoW) and add adjustable parameters. The longer a node rests after creating a block, the less difficult it is to create another new block, hence the term PoR. The penalty for slack nodes, the joining and quitting of nodes, and the adjustment of the expected block creation time can all be accomplished using the strong smart contracts, so the consortium blockchain can realize self-renewal.
In decentralized finance (DeFi), lenders can offer flash loans to borrowers, i.e., loans that are only valid within a blockchain transaction and must be repaid with fees by the end of that transaction. Unlike normal loans, flash loans allow borrowers to borrow large assets without upfront collaterals deposits. Malicious adversaries use flash loans to gather large assets to exploit vulnerable DeFi protocols. In this paper, we introduce a new framework for automated synthesis of adversarial transactions that exploit DeFi protocols using flash loans. To bypass the complexity of a DeFi protocol, we propose a new technique to approximate the DeFi protocol functional behaviors using numerical methods (polynomial linear regression and nearest-neighbor interpolation). We then construct an optimization query using the approximated functions of the DeFi protocol to find an adversarial attack constituted of a sequence of functions invocations with optimal parameters that gives the maximum profit. To improve the accuracy of the approximation, we propose a novel counterexample driven approximation refinement technique. We implement our framework in a tool named FlashSyn. We evaluate FlashSyn on 16 DeFi protocols that were victims to flash loan attacks and 2 DeFi protocols from Damn Vulnerable DeFi challenges. FlashSyn automatically synthesizes an adversarial attack for 16 of the 18 benchmarks. Among the 16 successful cases, FlashSyn identifies attack vectors yielding higher profits than those employed by historical hackers in 3 cases, and also discovers multiple distinct attack vectors in 10 cases, demonstrating its effectiveness in finding possible flash loan attacks.
Les preuves vérifiables de manière probabiliste (PCP, de l'anglais "probabilistically checkable proofs), les preuves interactives (IP, pour "interactive proofs") ou encore les preuves à divulgation nulle de connaissance ("zero-knowledge proofs") ont la particularité d'admettre une vérification probabilististe. Ces systèmes de preuves probabilistes interviennent dans les constructions de schémas de calcul vérifiable, des protocoles cryptographiques permettant de vérifier très rapidement qu'un long calcul a été correctement effectué. En 2016, un nouveau modèle de preuve a été introduit par Ben-Sasson, Chiesa et Spooner : celui des preuves interactives par oracle (IOP, pour "interactive oracle proofs"). Ce modèle généralise à la fois les PCPs et les IPs et a suscité beaucoup d'intérêt depuis son introduction. Le modèle IOP a mené à d'intéressants résultats théoriques sur les arguments non-interactifs succincts et transparents ainsi qu'à des déploiements industriels.Un problème récurrent dans les constructions de systèmes de preuves probabilistes est celui de tester efficacement la proximité à un code correcteur d'erreurs. Le but est de déterminer si un certain mot appartient à un code linéaire donné, ou bien s'il est éloigné de tout mot de ce code. Les tests de proximité à des codes polynomiaux peuvent être interprétés comme des tests de bas degré. Par exemple, un important sous-protocole utilisé dans de nombreuses constructions pratiques est un "IOP of Proximity" pour les codes de Reed-Solomon (Ben-Sasson et al., ICALP 2018).Dans cette thèse, nous proposons dans le modèle IOP des protocoles permettant de vérifier la proximité à des codes correcteur d'erreurs.En nous inspirant du test de proximité pour les codes de Reed-Solomon de Ben-Sasson et al., nous commençons par formuler un cadre abstrait et générique pour construire des "IOPs of Proximity" pour des codes linéaires et en analysons formellement les propriétés. Nous appliquons ensuite cette méthodologie à différentes familles de codes généralisant les codes de Reed-Solomon. Il s'agit d'une part de codes définis à partir d'évaluations de polynômes multivariés et, d'autre part, de codes de géométrie algrébrique définis sur des courbes. Nos protocoles permettent de tester la proximité à des codes présentant des propriétés attrayantes par rapport aux codes de Reed-Solomon (telles que des alphabets de petite taille), tout en ayant une efficacité similaire à la construction de Ben-Sasson et al.
Blockchain has been witnessed a growing application in mobile communication. The application field ranges from the Internet of Things (IoT), Vehicle to Everything (V2X), Mobile Edge Computing (MEC), etc. The conjunction with blockchain can significantly avoid data tempering and protect user privacy. Although blockchain guarantees the security of mobile communication, the operation cost is increasing. The consensus algorithm of blockchain drives multiple untrust parties to keep data consistency, and it generates a large number of communication overheads. In this letter, we focus on the Byzantine Fault Tolerance (BFT) type of consensus and conduct a performance model. By utilizing the deterministic network calculus method, we analyze the delay bound of the Practical Byzantine Fault Tolerance (PBFT) and HotStuff consensus algorithm. The result of the simulation provides a valuable guideline for delay-sensitive blockchain-based applications.