31. Glossary

BFT (Byzantine Fault Tolerance) — the property that a protocol remains correct even if up to f participants behave arbitrarily; Quantos committees tolerate f = ⌊(n-1)/3⌋.

Bullshark — a DAG-based BFT consensus protocol under partial synchrony; source of Quantos's fast-path commit rule.

Checkpoint — a finality anchor produced by the super-committee every checkpoint_interval vertices, providing deterministic, irreversible finality.

Committee — A configurable, stake-weighted validator subset used for consensus and finality accounting. Size and topology are network parameters.

Compute Unit (CU) — the resource-accounting unit metered by STACC; replaces gas. Quotas are stake-proportional; CU is not charged as a fee.

Cross-shard transaction — A transaction touching accounts assigned to more than one shard. The repository contains coordination paths; atomicity and proof guarantees require validation of the deployed configuration.

DAG (Directed Acyclic Graph) — The vertex and parent-reference structure used by Quantos for propagation and ordering. It complements checkpoint finality rather than eliminating all linear state commitments.

Domain separation — prepending a context tag before hashing/signing so a signature in one context cannot be replayed in another.

Finality (deterministic) — The checkpoint-based finality path implemented by Quantos. Latency depends on checkpoint interval, validator participation and network conditions; no universal one-second guarantee is established.

GST (Global Stabilization Time) — in the partial-synchrony model, the unknown time after which message delays are bounded; liveness holds after GST, safety always.

HotStuff / HotStuff-2 — linear-message-complexity, rotating-leader BFT; basis of Quantos's pipelined committee consensus.

L0 Finality Hub — The cross-chain checkpoint and relay subsystem with chain-specific adapters and trust assumptions. Supported adapters are not automatically trustless light clients.

ML-DSA-65 — NIST FIPS 204 lattice signature scheme used by Quantos for transaction and checkpoint/finality signatures.

ML-KEM-768 — NIST FIPS 203 key-encapsulation mechanism, represented by the repository's Kyber-compatible KEM path for PQ key establishment.

Rescue-Prime + STARK VRF — The hash-based verifiable-randomness design described by the official repository for committee selection and rotation.

MVCC (Multi-Version Concurrency Control) — snapshot-isolation technique enabling lock-free parallel execution with commit-time conflict detection.

Narwhal — a DAG-based mempool with structured data availability; basis of Quantos's transaction dissemination.

PBS (Proposer-Builder Separation) — separating block building from proposing via a sealed-bid builder market to democratize MEV.

PQC (Post-Quantum Cryptography) — Cryptography intended to resist known quantum attacks. Quantos currently uses different PQC-compatible primitives by subsystem.

PQC-Guard — a quantum-resistant smart account deployable on external chains, releasing funds via M-of-N WOTS attestations from Quantos validators.

QN4 / QN8 / QN12 — native fungible / non-fungible / multi-token standards (ERC-20 / 721 / 1155 equivalents).

QTS — The intended native staking and resource-accounting asset. Supply and mainnet monetary policy are not finalized by the current repository.

Quorum Certificate (QC) — an aggregate of committee votes representing >2/3 stake, certifying a vertex or checkpoint.

Re-sharding — safe migration of accounts between shards, with draining, freezing, 2-phase commit, and bounded rollback.

Slashing — Configurable evidence-based penalty and possible jailing for provable validator misbehaviour. Final percentages and destinations are network parameters, not universal constants.

STACC (Stake-Timed Access and Compute Credit) — Quantos's resource-accounting subsystem for quotas, compute-unit limits, admission and scheduling. “Zero gas” does not mean zero validator cost.

STARK — A transparent proof system used by the L0 batch aggregation module and the Rescue-Prime + STARK VRF path.

State rent — A configurable collector for persistent storage with exemption, grace-period and expiration logic. Its economic denomination and distribution are not finalized.

Vertex — a unit of the DAG bundling transactions and referencing 2–8 parents.

VRF — Quantos's Rescue-Prime + STARK hash-based randomness path for stake-weighted committee selection and rotation; proof soundness and distributed behavior remain subject to implementation and adversarial validation.

WOTS (Winternitz One-Time Signature) — a hash-based one-time signature verified with keccak256; the on-chain verification primitive for PQC-Guard.