DA-05 · LESSON 04

Nostr transport

KEY DEFINITIONS

Terms used in this lesson

Nostr: A signed-event messaging protocol; Ducat can use relays to distribute oracle material without making those relays Bitcoin validators.
Identifier: Identifier: a value used to distinguish one request, object, or participant from another.
Oracle: A system that reports outside information, such as a market price, for use by a protocol.
Validator: Software or a participant that independently checks state transitions under a system's rules. The exact role depends on the protocol being discussed.
NIP-33: A Nostr specification for parameterized replaceable events identified by author, kind, and a d tag.
NIP-01: The basic Nostr protocol specification that defines signed event fields, event identifiers, and signature verification.
SHA-256: A cryptographic hash function used throughout Bitcoin to produce fixed-size 256-bit digests.
UTF-8: A standard variable-length byte encoding for Unicode text.
JSON: JavaScript Object Notation: a text format that represents structured fields such as arrays, strings, numbers, and objects.
BIP340: The Bitcoin Improvement Proposal specifying Schnorr signatures for the secp256k1 curve.
Schnorr signature: Bitcoin’s Taproot signature scheme, whose algebra supports compact verification and advanced multi-party signing.

Replaceable signed events distribute current snapshots, threshold contracts, and breach material; relays transport data but are not the trust anchor.

65 min Difficulty 4/5 Not started

VISUAL MODEL

See the whole mechanism before going step by step

Use the diagrams to orient yourself. Then the guided explanation below teaches every part in depth.

4 explanatory views

CONCEPT-SPECIFIC MAP · ducat vaultA Ducat action moves one Bitcoin-anchored vault state to a successorSelect any state to inspect its exact role.

RELATIONSHIP MAPInputs, rule, and outputs

01
PREDECESSORCurrent vault outpoint
The current Bitcoin output anchors collateral and identifies the state being spent.
02
REQUESTNostr transport
The Nostr transport workflow proposes one exact action and successor state.
03
POLICYProfile, oracle, signatures
Applicable policy, price evidence, authorization, and transaction shape are checked.
04
BITCOIN SPENDScript-valid transaction
Bitcoin miners and nodes can include only a transaction that satisfies Bitcoin rules.
05
SUCCESSORNew outpoint and state
Ducat validators reconstruct debt, collateral, token, and account changes from the confirmed transaction.

Rule shown: Bitcoin checks the spend; Ducat components independently reconstruct and validate the additional protocol state.

STAGE 1 OF 5PREDECESSOR: Current vault outpoint

The current Bitcoin output anchors collateral and identifies the state being spent.

Governing relationship: Bitcoin checks the spend; Ducat components independently reconstruct and validate the additional protocol state. Complete path: 1. PREDECESSOR, Current vault outpoint. The current Bitcoin output anchors collateral and identifies the state being spent. 2. REQUEST, Nostr transport. The Nostr transport workflow proposes one exact action and successor state. 3. POLICY, Profile, oracle, signatures. Applicable policy, price evidence, authorization, and transaction shape are checked. 4. BITCOIN SPEND, Script-valid transaction. Bitcoin miners and nodes can include only a transaction that satisfies Bitcoin rules. 5. SUCCESSOR, New outpoint and state. Ducat validators reconstruct debt, collateral, token, and account changes from the confirmed transaction.

1. State transitionWhat exists, what changes, and what results

BEFORE

A kind 30000 event represents the 1.60 ladder entry at quote timestamp 1,700,000,000. Its d tag is 1700000000-1.60, its h tag is the commitment hash, and its expires tag is 1…

MECHANISM

The oracle key signs fields and tags so clients can verify authorship and detect mutation.

AFTER

The event ID authenticates an exact serialization. A relay can withhold or replay an event, but it cannot alter a signed field without invalidating the ID and signature.

Text equivalent: Starting from A kind 30000 event represents the 1.60 ladder entry at quote timestamp 1,700,000,000. Its d tag is 1700000000-1.60, its h tag is the commitment hash, and its expires tag is 1700001800. The mechanism begins when The oracle key signs fields and tags so clients can verify authorship and detect mutation. The resulting lesson is The event ID authenticates an exact serialization. A relay can withhold or replay an event, but it cannot alter a signed field without invalidating the ID and signature.

2. Mechanism pathSelect a stage to inspect its job

STAGE 1 OF 4

Sign event content

The oracle key signs fields and tags so clients can verify authorship and detect mutation.

Complete path: 1. Sign event content: The oracle key signs fields and tags so clients can verify authorship and detect mutation. 2. Publish by event kind: The captured workflow uses kind 10001 for pending snapshots, kind 30000 for threshold contracts, and kind 10000 for the current snapshot. 3. Use replaceable identity: NIP-33 identifiers let a newer event replace the same logical record without making relay order authoritative. 4. Verify after retrieval: Clients check signature, network, key, tags, timestamp, freshness, commitment, and content rather than trusting the relay connection.

3. Rule and failure boundaryWhat accepts the result and where it can stop

ACCEPTED PATH

The worked case executes the named inputs and checks in the displayed order. Clients check signature, network, key, tags, timestamp, freshness, commitment, and content rather than trusting the relay connection.

CHANGED CONDITION

A missing, malformed, stale, unauthorized, or inconsistent required input stops at its first named boundary. Relays transport signed records. Clients authenticate content and apply snapshot and freshness rules independently.

Important distinction: The first relay response decides the current oracle truth. Relays transport signed records. Clients authenticate content and apply snapshot and freshness rules independently.

Text equivalent: The accepted path is enforced by The worked case executes the named inputs and checks in the displayed order. Clients check signature, network, key, tags, timestamp, freshness, commitment, and content rather than trusting the relay connection. If the required condition changes, A missing, malformed, stale, unauthorized, or inconsistent required input stops at its first named boundary. Relays transport signed records. Clients authenticate content and apply snapshot and freshness rules independently.

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Learn the idea

Nostr is a signed-event messaging protocol. Ducat uses relays to transport oracle snapshots, threshold contracts, and breach material. A relay stores and forwards events but does not become the oracle or a Bitcoin validator.

GUIDED EXPLANATION1/4 ideas inspected

Sign event content

The oracle key signs fields and tags so clients can verify authorship and detect mutation.

The worked example follows the explanation

Inspect every idea above to open it.

Important distinction“The first relay response decides the current oracle truth.”

Relays transport signed records. Clients authenticate content and apply snapshot and freshness rules independently.

FINISH LEARNING FIRST

The questions unlock after every required learning activity

Inspect every guided idea, open the worked example, rebuild its mechanism, and complete the deterministic lesson tool. Your progress is saved automatically.