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ID Tokens

Overview

ID Tokens are an OAuth2 extension introduced by OpenID Connect and Dex’s primary feature. ID Tokens are JSON Web Tokens (JWTs) signed by Dex and returned as part of the OAuth2 response that attest to the end user’s identity. An example JWT might look like:

eyJhbGciOiJSUzI1NiIsImtpZCI6IjlkNDQ3NDFmNzczYjkzOGNmNjVkZDMyNjY4NWI4NjE4MGMzMjRkOTkifQ.eyJpc3MiOiJodHRwOi8vMTI3LjAuMC4xOjU1NTYvZGV4Iiwic3ViIjoiQ2djeU16UXlOelE1RWdabmFYUm9kV0kiLCJhdWQiOiJleGFtcGxlLWFwcCIsImV4cCI6MTQ5Mjg4MjA0MiwiaWF0IjoxNDkyNzk1NjQyLCJhdF9oYXNoIjoiYmk5NmdPWFpTaHZsV1l0YWw5RXFpdyIsImVtYWlsIjoiZXJpYy5jaGlhbmdAY29yZW9zLmNvbSIsImVtYWlsX3ZlcmlmaWVkIjp0cnVlLCJncm91cHMiOlsiYWRtaW5zIiwiZGV2ZWxvcGVycyJdLCJuYW1lIjoiRXJpYyBDaGlhbmcifQ.OhROPq_0eP-zsQRjg87KZ4wGkjiQGnTi5QuG877AdJDb3R2ZCOk2Vkf5SdP8cPyb3VMqL32G4hLDayniiv8f1_ZXAde0sKrayfQ10XAXFgZl_P1yilkLdknxn6nbhDRVllpWcB12ki9vmAxklAr0B1C4kr5nI3-BZLrFcUR5sQbxwJj4oW1OuG6jJCNGHXGNTBTNEaM28eD-9nhfBeuBTzzO7BKwPsojjj4C9ogU4JQhGvm_l4yfVi0boSx8c0FX3JsiB0yLa1ZdJVWVl9m90XmbWRSD85pNDQHcWZP9hR6CMgbvGkZsgjG32qeRwUL_eNkNowSBNWLrGNPoON1gMg

ID Tokens contains standard claims assert which client app logged the user in, when the token expires, and the identity of the user.

{
  "iss": "http://127.0.0.1:5556/dex",
  "sub": "CgcyMzQyNzQ5EgZnaXRodWI",
  "aud": "example-app",
  "exp": 1492882042,
  "iat": 1492795642,
  "at_hash": "bi96gOXZShvlWYtal9Eqiw",
  "email": "jane.doe@coreos.com",
  "email_verified": true,
  "groups": [
    "admins",
    "developers"
  ],
  "name": "Jane Doe"
}

Because these tokens are signed by Dex and contain standard-based claims other services can consume them as service-to-service credentials. Systems that can already consume OpenID Connect ID Tokens issued by Dex include:

For details on how to request or validate an ID Token, see Writing apps that use Dex.”

Refresh tokens

Refresh tokens are credentials used to obtain access tokens. Refresh tokens are issued to the client by the authorization server and are used to obtain a new id token when the current id token becomes invalid or expires. Issuing a refresh token is optional and is provided by passing offline_access scope to Dex server.

NOTE: Some connectors do not support offline_access scope. You can find out which connectors support refresh tokens by looking into the connectors list .

Example of a server response with refresh token:

{
 "access_token": "eyJhbGciOiJSUzI1N...",
 "token_type": "Bearer",
 "refresh_token": "lxzzsvasxho5exvwkfa5zhefl",
 "expires_in": 3600,
 "id_token": "eyJhbGciO..."
}

NOTE: For every refresh of an id token, Dex issues a new refresh token. This security measure is called refresh token rotation and prevents someone stealing it. The idea is described in detail in the corresponding RFC .

Expiration and rotation settings

Dex has a section in the config file where you can specify expiration and rotation settings for id tokens and refresh tokens. NOTE: All duration options should be set in the format: number + time unit (s, m, h), e.g., 10m.

  • expire - section for various expiration settings, including token settings:
    • idTokens - the lifetime of id_token. It is preferable to use short-lived id tokens.
    • refreshTokens - section for various refresh token settings:
      • validForIfNotUsed - invalidate a refresh token if it is not used for a specified amount of time.
      • absoluteLifetime - a stricter variant of the previous option, absolute lifetime of a refresh token. It forces users to reauthenticate and obtain a new refresh token.
      • disableRotation - completely disables every-request rotation. The user will also have to specify one of the previous refresh token options to keep refresh tokens secure when toggling this.
      • reuseInterval - allows getting the same refresh token from refresh endpoint within a specified interval, but only if the user’s request contains the previous refresh token.

NOTE: disableRotation and reuseInterval options help effectively deal with network lags, concurrent requests, and so on in tradeoff for security. Use them with caution.