Beyond Single Proposers: A New Approach to Blockchain Transaction Dissemination

Author: Denis Avetisyan

Sedna introduces a novel protocol leveraging verifiable rateless coding to efficiently and securely distribute transactions across multiple concurrent proposer blockchains.

For a system designed to withstand censorship-with parameters including $n=256$, a censorship rate of $c_{e}/n=0.125$, and a failure probability of $\delta=10^{-9}$-replication factors utilizing Sedna’s multi-dimensional scaling and rateless techniques demonstrate comparable resilience to naive replication, suggesting alternative approaches needn't sacrifice protection against data loss or manipulation. — For a system designed to withstand censorship-with parameters including $n=256$, a censorship rate of $c_{e}/n=0.125$, and a failure probability of $\delta=10^{-9}$-replication factors utilizing Sedna’s multi-dimensional scaling and rateless techniques demonstrate comparable resilience to naive replication, suggesting alternative approaches needn’t sacrifice protection against data loss or manipulation.

This paper details Sedna, a system designed to optimize bandwidth, enhance censorship resistance, and mitigate Miner Extractable Value (MEV) in multi-proposer blockchain environments.

Modern blockchains increasingly adopt multi-proposer consensus to improve scalability and censorship resistance, yet efficiently disseminating transactions to these proposers remains a critical challenge. This paper introduces Sedna: Sharding transactions in multiple concurrent proposer blockchains, a user-facing protocol leveraging verifiable rateless coding to replace naive transaction replication. Sedna optimizes bandwidth, enhances censorship resistance, and minimizes pre-inclusion information leakage-significantly reducing opportunities for malicious miner extraction of value (MEV). By approaching information-theoretic bandwidth limits, can Sedna unlock a new era of efficient and private transaction dissemination in decentralized systems?

The Erosion of Efficiency: Traditional Blockchain Dissemination

Contemporary blockchain networks frequently employ a transaction dissemination strategy known as Naive Replication, wherein each node broadcasts received transactions to all peers. While conceptually straightforward, this approach presents significant challenges as network size increases. The sheer volume of redundant broadcasts rapidly consumes bandwidth and imposes substantial computational burdens on each node, hindering scalability. More critically, this reliance on broad, often centralized, dissemination pathways introduces vulnerabilities to censorship; malicious actors or compromised entities can effectively block transactions by preventing their propagation across the network. This undermines the foundational promise of blockchain technology – a tamper-proof and censorship-resistant system for value transfer – necessitating the exploration of more efficient and robust dissemination protocols.

Traditional blockchain transaction broadcasting relies on replicating transaction data across the network, a process that places substantial demands on bandwidth and computational power. Each full node must download, verify, and relay every transaction, leading to rapidly escalating costs as network activity increases. This resource intensity not only limits the number of transactions the network can process-constraining throughput and creating potential bottlenecks-but also presents a barrier to entry for potential nodes, hindering decentralization. The escalating costs associated with maintaining a full node can effectively exclude individuals and smaller organizations, concentrating network control in the hands of entities with greater resources. Consequently, improving dissemination efficiency is crucial for fostering a truly scalable and accessible blockchain ecosystem, demanding innovative approaches that minimize resource consumption without compromising security or reliability.

The inherent structure of traditional transaction broadcasting creates vulnerabilities to censorship, directly challenging blockchain’s decentralized ethos. When transaction dissemination relies on a limited number of nodes or pathways – even if not overtly controlled by a single entity – these points become potential targets for malicious actors. These actors can selectively block or delay transactions, effectively censoring specific users or types of activity without necessarily requiring full network control. This disruption isn’t necessarily about preventing transactions entirely, but about manipulating their order or visibility, potentially causing financial harm or suppressing dissenting viewpoints. Consequently, the promise of a censorship-resistant system is compromised if dissemination isn’t sufficiently robust and distributed, highlighting the critical need for alternative broadcasting mechanisms that prioritize resilience and openness.

Despite encoding overhead, rateless coding outperforms naive replication in end-to-end latency across validator set sizes from 16 to 8192 due to significant bandwidth savings from reduced data transmission.

Sedna: A Paradigm Shift in Transactional Resilience

Sedna employs Rateless Coding as a core mechanism to overcome limitations inherent in traditional, full-transaction replication. This technique decomposes each transaction into multiple, independent coded symbols. Unlike replication which requires the complete transaction data to be present for verification, Rateless Coding allows for successful reconstruction of the original transaction with a significantly smaller subset of these symbols. Each symbol is independently verifiable, enhancing data integrity. The number of symbols generated exceeds the amount necessary for reconstruction, providing redundancy and resilience against data loss or network interruptions. This approach substantially reduces the data volume required for dissemination compared to full replication, improving network efficiency and lowering bandwidth costs.

Sedna’s architecture improves both privacy and network resilience by fragmenting transaction data into coded symbols before dissemination. Instead of replicating entire transactions across the network, Sedna employs rateless coding to generate these symbols, allowing reconstruction of the original transaction from any sufficient subset. These symbols are then distributed through a network referred to as ‘Lanes,’ creating multiple redundant paths for data delivery. This approach mitigates the impact of network disruptions, as data loss in one or more Lanes does not necessarily prevent successful transaction reconstruction. Furthermore, distributing data as coded symbols, rather than complete transactions, inherently enhances privacy by obscuring the original data content across multiple network nodes.

Sedna utilizes ‘Bundles’ as the primary unit of data transmission, effectively packaging multiple coded symbols – fragments of a transaction – into a single message. These Bundles are then addressed to specific ‘Lanes’ within the network, enabling targeted delivery and reducing broadcast overhead. The composition of each Bundle is dynamically determined based on network conditions and Lane availability, optimizing for efficient delivery and minimizing redundant transmissions. This bundling approach also reduces per-symbol metadata, further decreasing the overall network load compared to traditional, whole-transaction replication methods. By aggregating symbols, Sedna streamlines data propagation and enhances the scalability of the dissemination process.

The Sedna system incorporates a ‘Committed Payload’ to guarantee data integrity and prevent malicious alteration of transaction content. This payload functions as a cryptographically signed commitment to the transaction data before it is divided into coded symbols. Specifically, the payload contains a hash of the original transaction data, which is then verified by receivers upon reconstruction. This verification process ensures that any tampering with the coded symbols during transmission will be detectable, as the reconstructed data will not match the committed hash. Consequently, the Committed Payload provides a robust mechanism against malicious actors attempting to modify transaction details or introduce fraudulent information into the network.

Increasing the number of symbols improves rateless success probability but necessitates larger bundle sizes to maintain the same level of reliability, as demonstrated with parameters n=256, cₑ/n=0.125, δ=10⁻⁹, and S=32768 bytes.

Validating Resilience: Performance and Network Characteristics

Sedna utilizes rateless coding as an alternative to fixed-rate erasure coding schemes, such as Reed-Solomon (MDS) coding, to improve network performance in fluctuating conditions. Fixed-rate codes require a pre-defined number of fragments to be transmitted, regardless of network quality, potentially leading to wasted bandwidth or retransmissions. Rateless codes, however, dynamically adjust the redundancy introduced, allowing the receiver to reconstruct the original data with any sufficient subset of fragments. This adaptability directly maximizes ‘Network Goodput’ – the ratio of successfully delivered data to the total bandwidth utilized – as the system can continue operating efficiently even with packet loss or varying link capacities, unlike fixed-rate systems which may experience performance degradation or require costly retransmissions to maintain data integrity.

Sedna enhances censorship resistance by partitioning transaction data across multiple independent Lanes. This data distribution necessitates the collusion of a significant proportion of malicious proposers – those responsible for ordering transactions within a Lane – to successfully censor a transaction. Because each Lane operates independently, compromising a subset of proposers is insufficient to block transactions present on other Lanes. This approach contrasts with systems where a single entity or small group controls transaction ordering, and ensures that even if some Lanes experience malicious activity, transactions still have a high probability of being included and finalized across the network.

Sedna achieves high bandwidth efficiency by approaching the Information-Theoretic Lower Bound, a fundamental limit on data transmission rates. Traditional erasure coding methods often introduce significant overhead; however, Sedna’s rateless coding implementation minimizes this. Specifically, Sedna’s bandwidth overhead is mathematically defined as $ (1+ε)/(1-ce/n) $, where ε represents a small positive value controlling the probability of decoding failure, ‘c’ denotes the coding rate, and ‘n’ is the number of redundant data blocks. This formula demonstrates that as ‘n’ increases, the overhead approaches a theoretical minimum, resulting in demonstrably superior bandwidth utilization compared to fixed-rate methods like Maximum Distance Separable (MDS) coding, particularly in dynamic network conditions.

Sedna employs a Multi-Chain Proof-of-Stake (MCP) consensus mechanism to address scalability limitations inherent in single-leader consensus systems. Traditional architectures often experience bottlenecks as transaction volume increases, impacting finality times. MCP operates by sharding the consensus process across multiple leader nodes, each responsible for a subset of transactions. This parallel processing significantly reduces the burden on any single node, thereby increasing throughput and lowering latency. Furthermore, the use of cryptographic proofs allows for rapid verification of transactions processed by different leaders, achieving faster finality compared to systems reliant on sequential confirmation. The design ensures that finality is not dependent on the performance of a single entity, enhancing both speed and reliability.

Rateless coding overhead scales with censorship ratio, requiring increased redundancy for higher tolerance, but consistently decreases as payload size increases.

The Expanding Horizon: Implications and Future Trajectories

Sedna’s architecture is fundamentally designed to minimize the time between transaction submission and confirmation, directly fostering a low-latency environment for blockchain interactions. By streamlining the process of transaction propagation and inclusion, the system markedly reduces delays experienced by users, leading to demonstrably improved responsiveness in decentralized applications. This swift inclusion isn’t merely about speed; it unlocks possibilities for applications demanding real-time performance, such as decentralized exchanges and on-chain gaming, where even fractional delays can significantly impact usability and functionality. The efficient design enables a more fluid and engaging user experience, pushing the boundaries of what’s possible within blockchain technology and broadening its appeal to a wider audience seeking immediate and reliable interactions.

The architecture of Sedna actively mitigates opportunities for Miner Extractable Value (MEV) exploitation, fostering a more democratic blockchain landscape. By employing verifiable symbols and optimizing transaction dissemination, the system limits the ability of malicious actors to reorder, censor, or insert transactions for personal profit. This reduction in the “MEV surface” – the scope for profitable manipulation – levels the playing field, ensuring that transaction inclusion isn’t dictated by who can pay the highest fee for prioritization. Consequently, users experience a more predictable and equitable environment, where transactions are processed based on legitimate network demand rather than strategic front-running or other forms of manipulation, thereby promoting trust and wider participation within the blockchain ecosystem.

Sedna’s architecture facilitates transaction dissemination at significantly reduced costs, addressing a key barrier to wider blockchain adoption. Traditional models often involve prohibitively expensive fees for prioritizing transaction inclusion, effectively limiting participation to those with substantial resources. By optimizing the process of symbol verification and broadcast, Sedna lowers these economic hurdles, enabling a more inclusive financial ecosystem. This reasonable pricing structure not only makes blockchain technology accessible to a broader user base, including smaller applications and individual users, but also encourages greater innovation and participation in decentralized systems, ultimately fostering a more democratic and equitable digital landscape.

Sedna’s architecture intentionally minimizes the amount of information revealed about pending transactions before they are formally included in a block, significantly bolstering user privacy. Traditional blockchain systems often broadcast details of transactions to the network before finalization, creating opportunities for front-running and other privacy-invasive activities. Sedna circumvents this by employing a system where transaction data remains largely concealed until consensus is reached, limiting the ability of external observers to infer details about senders, receivers, or amounts. This reduction in pre-inclusion information leakage isn’t simply about obscuring data; it fundamentally alters the economic incentives that drive surveillance on the blockchain, fostering a more private and secure environment for all users and applications built upon the network.

The Sedna protocol, as detailed in the paper, attempts to build resilience into a system inherently susceptible to disruption. It acknowledges the inevitable propagation of errors – or, in this context, data loss and censorship attempts – within a network. This echoes a fundamental principle of decaying systems: perfect preservation is an illusion. Sedna’s use of verifiable rateless coding isn’t about eliminating these vulnerabilities, but distributing the risk, ensuring functionality persists even with partial failure. As Carl Friedrich Gauss observed, “Errors are inevitable, but they are also the seeds of progress.” The protocol doesn’t promise a flawless dissemination of transactions, but a graceful degradation of service under duress, a characteristic of systems designed to endure rather than avoid the passage of time. The minimization of pre-inclusion information leakage and MEV opportunities isn’t about stopping exploitation entirely, but delaying and distributing it – acknowledging that stability is often just a postponement of inevitable challenges.

What Lies Ahead?

Sedna addresses transaction dissemination with a pragmatism born of necessity – a recognition that bandwidth is finite, and information, once released, decays into exploitable pre-inclusion data. The protocol’s reliance on verifiable rateless coding is a step toward graceful degradation; a system accepting that complete information delivery is an ideal, not a guarantee. However, the inherent complexity of rateless codes introduces latency, and the optimization of coding parameters remains a moving target, susceptible to evolving network conditions and adversarial behavior. Future work must rigorously examine the trade-offs between redundancy, latency, and computational cost-a constant negotiation with the medium of time.

The mitigation of Miner Extractable Value (MEV) through information obfuscation is a temporary reprieve, not a permanent solution. Adversaries adapt. The pursuit of “until-decode privacy” is, in effect, a race to increase the cost of information recovery. Further research should explore dynamic coding schemes, adapting to real-time MEV pressures, and investigate the potential for integrating zero-knowledge proofs to further obscure transaction details. It’s a constant cycle of concealment and revelation-a system maturing through attempted breaches.

Ultimately, Sedna, and protocols like it, are not solving the problem of blockchain vulnerabilities; they are shifting the attack surface. The true measure of success will not be in eliminating MEV or censorship entirely, but in increasing the cost and complexity of these attacks to the point where they become economically unsustainable. Time, as always, will reveal the limitations of even the most elegant designs.

Original article: https://arxiv.org/pdf/2512.17045.pdf

Contact the author: https://www.linkedin.com/in/avetisyan/

The Erosion of Efficiency: Traditional Blockchain Dissemination

Sedna: A Paradigm Shift in Transactional Resilience

Validating Resilience: Performance and Network Characteristics

The Expanding Horizon: Implications and Future Trajectories

What Lies Ahead?

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