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1. Low-Latency Dynamically Available Total Order Broadcast

   Yandamuri, Sravya; Shrestha, Nibesh; Zanolini, Luca; Nayak, Kartik (March 2026, Financial Cryptography 2026)

   This work addresses the problem of Byzantine Fault-Tolerant (BFT) Total-Order Broadcast (TOB) in a dynamically available setting, where parties can transition between online and offline states without knowing the number of active parties. Dynamically available protocols are known to not be secure if parties commit at the speed of the network. In line with this result, existing dynamically available protocols rely on a synchronous network assumption, which means their latency remains tied to the pessimistic network delay Δ , even when the actual network delay is 𝛿 << Δ . This raises the question of whether a dynamically available BFT TOB protocol can maintain safety and liveness under synchrony while committing blocks with latency closer to the actual network delay. We answer this question affirmatively by designing the first dynamically available BFT TOB protocol that can commit blocks at the rate of 1 block per 𝑂 ( Δ 𝑖𝑑𝑒𝑎𝑙 ) time in expectation, where Δ 𝑖𝑑𝑒𝑎𝑙 < 2 𝛿 . 

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2. Constant Latency in Sleepy Consensus

   https://doi.org/10.1145/3548606.3559347  

   Momose, Atsuki; Ren, Ling (November 2022, Proceedings of the 2022 ACM SIGSAC Conference on Computer and Communications Security)

   Dynamic participation support is an important feature of Bitcoin's longest-chain protocol and its variants. But these protocols suffer from long latency as a fundamental trade-off. Specifically, the latency depends at least on the following two factors: 1) the desired security level of the protocol, and 2) the actual participation level of the network. Classic BFT protocols, on the other hand, can achieve constant latency but cannot make progress under dynamic participation. In this work, we present a protocol that simultaneously supports dynamic participation and achieves constant latency. Our core technique is to extend the classic BFT approach from static quorum size to dynamic quorum size, i.e., according to the current participation level, while preserving important properties of static quorum. We also present a recovery mechanism for rejoining nodes that is efficient in terms of both communication and storage. Our experimental evaluation shows our protocol has much lower latency than a longest-chain protocol, especially when there is a sudden decrease of participation. 

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3. The Hermes BFT for Blockchains

   https://doi.org/10.1109/TDSC.2021.3114310  

   Jalalzai, Mohammad Mussadiq; Feng, Chen; Busch, Costas; Richard III, Golden; Niu, Jianyu (October 2021, IEEE Transactions on Dependable and Secure Computing)

   The performance of partially synchronous BFT-based consensus protocols is highly dependent on the primary node. All participant nodes in the network are blocked until they receive a proposal from the primary node to begin the consensus process. Therefore, an honest but slack node (with limited bandwidth) can adversely affect the performance when selected as primary. Hermes decreases protocol dependency on the primary node and minimizes transmission delay induced by the slack primary while keeping low message complexity and latency with high scalability. Hermes achieves these performance improvements by relaxing strong BFT agreement (safety) guarantees only for a specific type of Byzantine faults (also called equivocated faults). Interestingly, we show that in Hermes equivocating by a Byzantine primary is expensive and ineffective. Therefore, the safety of Hermes is comparable to the general BFT consensus. We deployed and tested Hermes on 190 Amazon EC2 instances. In these tests, Hermes's performance was comparable to the state-of-the-art BFT protocol for blockchains (when the network size is large) in the absence of slack nodes. Whereas, in the presence of slack nodes, Hermes outperforms the state-of-the-art BFT protocol significantly in terms of throughput and latency. 

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4. Fluid MPC: Secure Multiparty Computation with Dynamic Participants

   https://doi.org/10.1007/978-3-030-84245-1_4  

   Choudhuri, A.R. (August 2021, Advances in Cryptology, CRYPTO 2021)

   Malkin, T. (Ed.)

   Existing approaches to secure multiparty computation (MPC) require all participants to commit to the entire duration of the protocol. As interest in MPC continues to grow, it is inevitable that there will be a desire to use it to evaluate increasingly complex functionalities, resulting in computations spanning several hours or days. Such scenarios call for a dynamic participation model for MPC where participants have the flexibility to go offline as needed and (re)join when they have available computational resources. Such a model would also democratize access to privacy-preserving computation by facilitating an “MPC-as-a-service” paradigm—the deployment of MPC in volunteer-operated networks (such as blockchains, where dynamism is inherent) that perform computation on behalf of clients. In this work, we initiate the study of fluid MPC, where parties can dynamically join and leave the computation. The minimum commitment required from each participant is referred to as fluidity, measured in the number of rounds of communication that it must stay online. Our contributions are threefold: We provide a formal treatment of fluid MPC, exploring various possible modeling choices. We construct information-theoretic fluid MPC protocols in the honest-majority setting. Our protocols achieve maximal fluidity, meaning that a party can exit the computation after receiving and sending messages in one round. We implement our protocol and test it in multiple network settings. 

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5. HotStuff-1: Linear Consensus with One-Phase Speculation

   https://doi.org/10.1145/3725308  

   Kang, Dakai; Gupta, Suyash; Malkhi, Dahlia; Sadoghi, Mohammad (June 2025, Proceedings of the ACM on Management of Data)

   This paper introduces HotStuff-1, a BFT consensus protocol that improves the latency of HotStuff-1 by two network hops while maintaining linear communication complexity against faults. Furthermore, HotStuff-1 incorporates an incentive-compatible leader rotation design that motivates leaders to propose transactions promptly. HotStuff-1 achieves a reduction of two network hops byspeculativelysending clients early finality confirmations, after one phase of the protocol. Introducing speculation into streamlined protocols is challenging because, unlike stable-leader protocols, these protocols cannot stop the consensus and recover from failures. Thus, we identifyprefix speculation dilemmain the context of streamlined protocols; HotStuff-1 is the first streamlined protocol to resolve it. HotStuff-1 embodies an additional mechanism,slotting, that thwarts delays caused by (1) rationally-incentivized leaders and (2) malicious leaders inclined to sabotage others' progress. The slotting mechanism allows leaders to dynamically drive as many decisions as allowed by network transmission delays before view timers expire, thus mitigating both threats. 

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