@canvas-js/interfaces

This package exports TypeScript types for Canvas messages and other interfaces.

Table of Contents

• Installation
• API
  • Signatures
  • Signers
  • Messages
  • Actions
  • Sessions
  • Session signers
  • Utility types
    • Awaitable

Installation

npm i @canvas-js/chain-interfaces

API

Signatures

import type { CID } from "multiformats"

export type Signature = {
  publicKey: string
  signature: Uint8Array
  cid: CID
}

Signers

import type { Signature } from "./Signature.js"

export interface Signer<T = any> {
  sign(value: T): Signature
}

Messages

export type Message<Payload = unknown> = {
  topic: string
  clock: number
  parents: string[]
  payload: Payload
}

Actions

export type Action = {
  type: "action"

  /** DID of the user that authorized the session (e.g. "did:pkh:eip155:1:0xb94d27...") */
  address: string

  name: string
  args: any

  context: {
    timestamp: number
    blockhash?: string
  }
}

Sessions

export type Session<AuthorizationData = any> = {
  type: "session"

  /** DID of the user that authorized the session (e.g. "did:pkh:eip155:1:0xb94d27...") */
  address: string

  /** did:key URI of the ephemeral session key used to sign subsequent actions */
  publicKey: string

  /** chain-specific session payload, e.g. a SIWE message & signature */
  authorizationData: AuthorizationData

  context: {
    blockhash?: string
    duration?: number
    timestamp: number
  }
}

Session signers

import type { Signer } from "./Signer.js"
import type { Message } from "./Message.js"
import type { Session } from "./Session.js"
import type { Action } from "./Action.js"
import type { Awaitable } from "./Awaitable.js"

export interface SessionSigner extends Signer<Action | Session> {
  match: (chain: string) => boolean

  /**
   * Produce an signed Session object, which authorizes `session.publicKey`
   * to represent the user `${session.chain}:${session.address}`.
   *
   * The signature is stored in `session.data`, and the entire Session
   * object is then signed using the session-key, and appended to our message log.
   */
  getSession: (topic: string, options?: { chain?: string; timestamp?: number }) => Awaitable<Session>

  /**
   * Verify that `session.data` authorizes `session.publicKey`
   * to take actions on behalf of the user `${session.chain}:${session.address}`
   */
  verifySession: (session: Session) => Awaitable<void>
}

Utility types

Awaitable

export type Awaitable<T> = T | Promise<T>