generated: '2026-07-20'
method: derived
source: https://github.com/21dotco/two1-python/blob/master/two1/server/rest_client.py
status: historical
notes: >-
  Earn.com / 21.co published no OpenAPI. This profile is derived from the
  first-party two1 client library's REST client, which is the only surviving
  authoritative description of how the api.21.co API was authenticated. The API
  is no longer reachable (api.21.co is NXDOMAIN as of 2026-07-20).
summary:
  types: [http, custom-signature]
  api_key_in: []
  oauth2_flows: []
  oauth2: false
  openid_connect: false
schemes:
- name: two1-wallet-signature
  type: custom-signature
  in: header
  header: Authorization
  format: '21 <iso8601-timestamp> <username> <signature>'
  description: >-
    Primary scheme. The client signs the concatenation of the request URL, an
    ISO-8601 timestamp, and the JSON request body with the user's bitcoin
    wallet key, then sends the signature in the Authorization header alongside
    the timestamp and username. Effectively a bitcoin-keypair-based HTTP
    message signature.
  signed_material: url + timestamp + body
  sources: [two1/server/rest_client.py]
- name: basic
  type: http
  scheme: basic
  description: >-
    HTTP Basic (username/password, base64) used only for the initial login
    exchange (POST /users/{username}/) before wallet-signature auth takes over.
  sources: [two1/server/rest_client.py]
additional_headers:
- name: User-Agent
  value: 21/<two1-version>
- name: From
  value: <wallet-public-key>@<device-id>
  description: Binds the request to the caller's wallet public key and device UUID.