@midnight-ntwrk/midnight-did-contract

Compact smart-contract implementation for Midnight DID ledger state.

Responsibilities

• Store DID state on-ledger (methods, relations, services, aliases, metadata)
• Enforce on-chain invariants and authorization checks
• Expose circuits for DID lifecycle operations

Architecture

graph TD
  API[API]
  Contract[did.compact circuits]
  Ledger[(On-chain DID state)]

  API --> Contract
  Contract --> Ledger

Circuit Flow (example: set verification method)

sequenceDiagram
  participant Caller
  participant Circuit as setVerificationMethod
  participant Ledger

  Caller->>Circuit: VerificationMethod input + MapMutation + controller signature
  Circuit->>Circuit: verify controller signature over contract id + version + operation + args
  Circuit->>Circuit: key type/curve constraints
  Circuit->>Circuit: duplicate/non-existence checks
  Circuit->>Ledger: insert/update state
  Circuit->>Ledger: increment version + operationCount

On-ledger State Lifecycle

stateDiagram-v2
  [*] --> Active
  Active --> Active : add/update/remove methods, relations, services, aliases
  Active --> Deactivated : deactivate()
  Deactivated --> [*]

Build & Test

• Compile compact artifacts only: pnpm --filter ./packages/contract contract
• Build prepared package outputs: pnpm --filter ./packages/contract build:prepared
• Tests: pnpm --filter ./packages/contract test -- --pool=threads
• Coverage: pnpm --filter ./packages/contract coverage

Notes

• Contract-level checks focus on enforceable on-chain invariants.
• Some full DID conformance checks are intentionally handled at SDK/domain layers.
• Controller public keys can be derived locally with deriveControllerPublicKey(secretKey) as Jubjub points. Controller-gated circuits verify wallet-local signatures over a domain-separated digest containing the DID contract id, current version, operation name, and operation arguments.
• Set/update circuits use explicit MapMutation and SetMutation enums so the exported circuit surface stays small without boolean intent flags.
• Jubjub signing helpers and reusable Schnorr transcript logic live in @midnight-ntwrk/midnight-did-jubjub-schnorr.
• The DID contract exposes one ledger-bound SchnorrJubjub verification circuit. It accepts a verification method id, looks up the native JubjubPoint stored in schnorrJubjubVerificationMethods, and verifies against that ledger key rather than a caller-supplied public key.
• Circuit k, rows, and managed artifact byte sizes are documented in docs-site/compact/index.md.