Protocol Overview

ZNS is a name service running entirely inside the memo field of standard Orchard shielded transactions on Zcash.

State is a pure function

State is a pure function of (chain, UIVK, admin_pubkey). Any operator with those three inputs produces the same database, byte-for-byte. The indexer is not a trusted oracle; it is a deterministic reducer over an append-only log of memos. For the reader-facing trust explanation, see Trust model.

Components

Memo protocol

Every write operation is a UTF-8 string in the 512-byte Orchard memo field, beginning with the literal prefix ZNS:. Seven actions: CLAIM, UPDATE, LIST, DELIST, BUY, RELEASE, SETPRICE. Each has a fixed grammar parsed by splitn on the colon byte 0x3A, and each carries a canonical Ed25519 signature pre-image as its final field. See Memo Format and Signature Scheme.

Indexer

A Rust service (zcashme/ZNS) that streams blocks from lightwalletd, trial-decrypts Orchard outputs against the registry’s UIVK, parses ZNS: memos, verifies signatures against admin_pubkey, applies admission rules (nonce monotonicity, claim cost, name format, pricing bootstrap), writes rows to SQLite, and exposes the registry over JSON-RPC 2.0 on port 3000. The scan loop is sequential and single-threaded; determinism is the design goal. See Running an Indexer.

ZVS

A separate Rust service for OTP-based address-ownership verification. The client sends a shielded transaction carrying a session memo to the ZVS address; ZVS replies with a 6-digit HMAC-SHA256 code in a shielded memo. ZVS sees no plaintext beyond the session token, never touches the registry, and cannot affect any registration. See OTP Protocol.

Clients

The web app, the SDKs (TypeScript here , Rust/Dart/Kotlin/Swift/Python/Go ports under zcashme/ZNS/sdk), and wallet integrations all consume the same JSON-RPC surface. A correctly-implemented client verifies the signature returned with every registration against a hardcoded admin_pubkey, and ideally runs its own indexer against a hardcoded UIVK.