Researchers Unveil Sieve-MMR: A Deterministic, Low-Latency Permissionless Blockchain Protocol

Global: Researchers Unveil Sieve-MMR: A Deterministic, Low-Latency Permissionless Blockchain Protocol

Researchers have introduced Sieve-MMR, a fully‑permissionless blockchain protocol that promises deterministic security and constant expected latency without relying on external consensus mechanisms. The work appears in an arXiv preprint posted in December 2025 and targets the global blockchain community seeking more robust consensus solutions.

Background on Permissionless Blockchains

Permissionless blockchains allow any node to join or leave at will, typically employing proof‑of‑work (PoW) or proof‑of‑stake (PoS) to achieve consensus. Both families have known weaknesses: PoS can suffer long‑range attacks that rewrite history at minimal cost, while PoW remains vulnerable to adversaries with sufficient computational power.

Introducing Sieve-MMR

Sieve-MMR adapts the deterministic, low‑latency MMR protocol—originally designed for PoS—to a PoW environment. By combining MMR’s constant‑expected‑latency guarantees with PoW’s resistance to long‑range attacks, the new protocol claims to deliver deterministic security without external social consensus.

Mitigating Time‑Travel Attacks

The authors identify a novel threat they term “time‑travel attacks,” where an adversary reuses PoW generated far in the past to inflate perceived mining power in the present. To counter this, they propose a time‑travel‑resilient broadcast (TTRB) primitive that limits the influence of stale PoW on current consensus.

Technical Innovation: The Sieve Algorithm

Sieve, the core algorithm, implements TTRB using a black‑box, deterministic PoW primitive. This design ensures that broadcast messages cannot be manipulated by replayed work, preserving the integrity of the messaging layer that underpins MMR’s consensus process.

Potential Impact on Blockchain Security

If validated in practice, Sieve-MMR could offer a new class of permissionless blockchains that avoid the trade‑offs inherent in current PoW and PoS designs. Deterministic security and predictable latency may make the protocol attractive for applications where transaction finality and resistance to historical tampering are critical.

Future Research Directions

The paper suggests further empirical evaluation on testnets and exploration of scalability under diverse network conditions. Additional analysis is needed to assess how the protocol behaves against coordinated attacks that combine computational and network‑level strategies.

This report is based on information from arXiv, licensed under Academic Preprint / Open Access. Based on the abstract of the research paper. Full text available via ArXiv.