arXiv subjects

Ben Marsh

Publications and source records attributed to Ben Marsh.

3 recordsLinked to original sources

arXiv2026

Domain Specific Post Quantum Signatures for Blockchains

Blockchains need more than post quantum single signer signatures. They need consensus profiled authentication objects with canonical bytes, priced invalid input rejection, stable transaction identifiers, hybrid downgrade resistance, public aggregation, merge semantics, accountable signer evidence, forward secure committee rotation, and light client consequences. We argue for domain specific post quantum signatures for blockchain roles, analogously to how hash function engineering produced domain specific primitives for hash table DoS and arithmetized proof systems. We formalize transaction authorization and quorum certificate requirements, instantiate them on Bitcoin, Ethereum, and a Sei Giga style high throughput BFT stress profile, and evaluate ML-DSA, SLH-DSA, Falcon/FN-DSA, HAWK, MAYO, SNOVA, UOV/QR-UOV, FAEST, SQIsign, LaBRADOR Falcon, Squirrel, Chipmunk, and DKKW/LeanSig. The conclusion is blunt. NIST single signer signatures are necessary components, although none of the current schemes is a drop in replacement for the signature layer of modern public blockchains. The missing object is a consensus ready post quantum signature profile, not another generic size table.

cs.CR↗

arXiv2026

You've Got a BUD in Me: Authenticated Reads from Per-Block Write Logs

Blockchains usually pay for authenticated reads by maintaining a structure that spans the entire state. We show how validators can support historical membership and exclusion proofs by authenticating each block's writes instead. A Block Update Digest (BUD) commits a write log whose predecessor pointers link successive modifications of each key. A SuperBUD summarizes last writes over a window; an exponential hierarchy turns long unchanged intervals into short proofs. The digest count is logarithmic in the gap within the hierarchy's range, with one additional digest per top-level window beyond it. We prove soundness against adversarial provers and up to f Byzantine validators, and completeness for queries anchored by a post-deployment modification, assuming archive, attestation, and committee evidence is available. Across a 50x increase in state size, the measured base-BUD path rises by 1.24x, compared with 3.1x and 69.5x for in-memory and cache-bounded disk-backed Merkle Patricia tries. On the synthetic trace, two-digest read-layer payloads stay below 800 bytes, and warm hash-path verification takes at most 146 microseconds at p99.

cs.CR↗

arXiv2026

Hermes: Low Tail-Latency Via Prefix Consensus

Leader-based BFT protocols finalize through their leaders: a view whose leader is crashed or slow finalizes nothing, and the timeout that ends it admits no good setting. A conservative timeout turns every crashed leader into a long stall; an aggressive one voids the views of leaders that are merely slow. Either way the expired view is wasted, and this trade-off, not the good case, governs tail latency. Hermes makes expired views finalize. Hermes is a two-round rotating-leader protocol for $n=5f+1$ processes under partial synchrony built on prefix consensus: votes carry values ordered by a prefix relation, and quorums require comparability rather than equality. Every process broadcasts a justified proposal at view start and casts a single vote, for the leader's proposal upon delivery or for a fallback proposal at the timeout; there are no nullify votes. A timely honest leader finalizes its full proposal in $2δ$. Otherwise, any $n-f$ votes, which need not match, finalize the heaviest common prefix. We instantiate Hermes as a finality gadget over an available chain and over Autobahn-style multi-lane dissemination, where parent-relative delta tipcuts with explicit skips keep independent proposals comparable and sender-indexed erasure-coded amplification keeps complexity at $O(n^2\hat{m}+λn^3)$ bits and $O(n^2)$ messages per view, where $\hat{m}$ is the number of concurrent dissemination lanes in Autobahn and $λ$ the security parameter.

cs.DC↗