Arrekta Protocol Specification

Version: 1.3 (pre-mainnet draft, 2026-10-28).

v1.3 adds the SHA256 policy hashlock (§4.2, for cross-chain swaps), finality proofs (§9.9, not consensus) and the provisional FN-DSA-512 scheme, regtest only (§3.1, §8). Pre-mainnet, so both are part of the launch rules, not a fork.
v1.2 adds merged mining (AuxPoW), a post-quantum chain-state commitment with snapshots, signed checkpoints, tail emission, fee bumping policy and P2P protocol 3.
v1.1 added policy locks, relative locks, transaction expiry, reserved lock kinds, version-bits deployments and committed compact block filters. Status: Normative. arrekta_core is the reference implementation, and core/vectors/ holds test vectors every implementation must reproduce. If this document and the reference code disagree, that is a bug to fix in one of them; neither silently wins.

Key words MUST, MUST NOT and MAY follow RFC 2119.

Sections

§	Section
1	Conventions
2	Hashing
3	Cryptography
4	Locks and witnesses
5	Transactions
6	Contextual transaction validation (`check_tx_inputs`)
7	Native assets
8	Crypto-agility: scheme schedules
9	Blocks
10	Proof of work and difficulty
11	Monetary policy and parameters
12	P2P protocol
13	Mempool policy (not consensus)
14	Node REST API
15	Versioning
16	Partially signed transactions (PST, wallet standard, not consensus)

See also the generated error code reference and the network parameters table.