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TokenX is our implementation of OAuth 2.0 Token Exchange.

For each hop in a request chain, a token is exchanged for a new token. The new token is scoped to a single target application and contains the original end-user identity.

There are primarily two distinct cases where one must use TokenX:

  1. You have a user facing app using ID-porten that should perform calls to another app on behalf of a user.
  2. You have an app receiving tokens issued from TokenX and need to call another app while still propagating the original user context.



See the NAIS manifest.

Getting Started

    enabled: true
        - application: app-2
        - application: app-3
          namespace: team-a
        - application: app-4
          namespace: team-b
          cluster: prod-gcp

Access Policies

In order for other applications to acquire a token targeting your application, you must explicitly specify inbound access policies that authorizes these other applications.

Thus, the access policies defines authorization on the application layer, and is enforced by Tokendings on token exchange operations.

For example:

    enabled: true
        - application: app-1
        - application: app-2
          namespace: team-a
        - application: app-3
          namespace: team-b
          cluster: prod-gcp

The above configuration authorizes the following applications:

  • application app-1 running in the same namespace and same cluster as your application
  • application app-2 running in the namespace team-a in the same cluster
  • application app-3 running in the namespace team-b in the cluster prod-gcp


Runtime Variables & Credentials

Your application will automatically be injected with both environment variables and files at runtime. You can use whichever is most convenient for your application.

The files are available at the following path: /var/run/secrets/

Variables for Exchanging Tokens

These variables are used for client authentication and exchanging tokens:

Name Description
TOKEN_X_CLIENT_ID Client ID that uniquely identifies the application in TokenX.
TOKEN_X_PRIVATE_JWK Private JWK containing an RSA key belonging to client.
TOKEN_X_TOKEN_ENDPOINT token_endpoint from the metadata discovery document.

Variables for Validating Tokens

These variables are used for token validation:

Name Description
TOKEN_X_CLIENT_ID Client ID that uniquely identifies the application in TokenX.
TOKEN_X_WELL_KNOWN_URL The URL for Tokendings' metadata discovery document.
TOKEN_X_ISSUER issuer from the metadata discovery document.
TOKEN_X_JWKS_URI jwks_uri from the metadata discovery document.

Client Authentication

Your application must authenticate itself with Tokendings when attempting to perform token exchanges. To do so, you must create a client assertion.

Create a JWT that is signed by your application using the private key contained within TOKEN_X_PRIVATE_JWK.

The assertion must contain the following claims:

Claim Example Value Description
sub dev-gcp:aura:app-a The subject of the token. Must be set to your application's own client_id, i.e. TOKEN_X_CLIENT_ID.
iss dev-gcp:aura:app-a The issuer of the token. Must be set to your application's own client_id, i.e. TOKEN_X_CLIENT_ID.
aud The audience of the token. Must be set to Tokendings' token_endpoint, i.e. TOKEN_X_TOKEN_ENDPOINT.
jti 83c580a6-b479-426d-876b-267aa9848e2f The JWT ID of the token. Used to uniquely identify a token. Set this to a UUID or similar.
nbf 1597783152 nbf stands for not before. It identifies the time (seconds after Epoch) before which the JWT MUST NOT be accepted for processing.
iat 1597783152 iat stands for issued at. It identifies the time (seconds after Epoch) in which the JWT was issued (or created).
exp 1597783272 exp is the expiration time (seconds after Epoch) of the token. This must not be more than 120 seconds after nbf and iat. That is, the maximum lifetime of the token must be no greater than 120 seconds.

Additionally, the headers of the assertion must contain the following parameters:

Parameter Value Description
kid 93ad09a5-70bc-4858-bd26-5ff4a0c5f73f The key identifier of the key used to sign the assertion. This identifier is available in the JWK found in TOKEN_X_PRIVATE_JWK.
typ JWT Represents the type of this JWT. Set this to JWT.
alg RS256 Represents the cryptographic algorithm used to secure the JWT. Set this to RS256.

The assertion should be unique and only used once. That is, every request to Tokendings should contain a unique client assertion:

  • Set the JWT ID (jti) claim to a unique value, such as an UUID.
  • Set the JWT expiry (exp) claim so that the lifetime of the token is reasonably low:
    • The maximum lifetime allowed is 120 seconds.
    • A lifetime between 10-30 seconds should be fine for most situations.

Example Client Assertion Values


  "kid": "93ad09a5-70bc-4858-bd26-5ff4a0c5f73f",
  "typ": "JWT",
  "alg": "RS256"


  "sub": "prod-gcp:namespace-gcp:gcp-app",
  "aud": "",
  "nbf": 1592508050,
  "iss": "prod-gcp:namespace-gcp:gcp-app",
  "exp": 1592508171,
  "iat": 1592508050,
  "jti": "fd9717d3-6889-4b22-89b8-2626332abf14"

Exchanging a token

To acquire a properly scoped token for a given target application, you must exchange an existing subject token (i.e. a token that contains a subject, in this case a citizen end-user).

Tokendings will then issue an access_token in JWT format, based on the parameters set in the token request. The token can then be used as a Bearer token in the Authorization header when calling your target API on behalf of the aforementioned subject.


  • You have a subject token in the form of an access_token issued by one of the following providers:
  • You have a client assertion that authenticates your application.

Exchange Request

The following denotes the required parameters needed to perform an exchange request.

Parameter Value Comment
grant_type urn:ietf:params:oauth:grant-type:token-exchange The identifier of the OAuth 2.0 grant to use, in this case the OAuth 2.0 Token Exchange grant. This grants allows applications to exchange one token for a new one containing much of the same information while still being correctly "scoped" in terms of OAuth.
client_assertion_type urn:ietf:params:oauth:client-assertion-type:jwt-bearer Identifies the type of assertion the client/application will use to authenticate itself to Tokendings, in this case a JWT.
client_assertion A serialized JWT identifying the calling app The client assertion; a JWT signed by the calling client/application used to identify said client/application.
subject_token_type urn:ietf:params:oauth:token-type:jwt Identifies the type of token that will be exchanged with a new one, in this case a JWT
subject_token A serialized JWT, the token that should be exchanged The actual token (JWT) containing the signed-in user. Should be an access_token.
audience The identifier of the app you wish to use the token for Identifies the intended audience for the resulting token, i.e. the target app you request a token for. This value shall be the client_id of the target app using the naming scheme <cluster>:<namespace>:<appname> e.g. prod-fss:namespace1:app1

Send the request to the token_endpoint, i.e. TOKEN_X_TOKEN_ENDPOINT.

POST /token HTTP/1.1
Content-Type: application/x-www-form-urlencoded


Exchange Response

Tokendings will respond with a JSON object

  "access_token" : "eyJraWQiOi..............",
  "issued_token_type" : "urn:ietf:params:oauth:token-type:access_token",
  "token_type" : "Bearer",
  "expires_in" : 899

The expires_in field denotes the lifetime of the token in seconds.

Cache and reuse the token until it expires to minimize network latency impact.

A safe cache key is key = sha256($subject_token + $audience).

Exchange Error Response

If the exchange request is invalid, Tokendings will respond with a structured error, as specified in RFC 8693, Section 2.2.2:

    "error_description" : "token exchange audience <some-audience> is invalid",
    "error" : "invalid_request"

Token Validation

If your app is a resource server / API and receives a token from another application, it is your responsibility to validate the token intended for your application.

Configure your app with the OAuth 2.0 Authorization Server Metadata found at the well-known endpoint, TOKEN_X_WELL_KNOWN_URL. Alternatively, use the resolved values from said endpoint for convenience:

Signature Verification

  • The token should be signed with the RS256 algorithm (defined in JWT header). Tokens not matching this algorithm should be rejected.
  • Verify that the signature is correct.
  • The issuer's signing keys can be retrieved from the JWK Set (JWKS) at the jwks_uri, i.e. TOKEN_X_JWKS_URI.
  • The kid attribute in the token header is thus a reference to a key contained within the JWK Set.
  • The token signature should be verified against the public key in the matching JWK.


The following claims are by default provided in the issued token and should explicitly be validated:

  • iss (issuer): The issuer of the token must match exactly with the Tokendings issuer URI (TOKEN_X_ISSUER).
  • aud (audience): The intended audience for the token, must match your application's client_id (TOKEN_X_CLIENT_ID).
  • exp (expiration time): Expiration time, i.e. tokens received after this date must be rejected.
  • nbf (not before time): The token cannot be used before this time, i.e. if the token is issued in the "future" (outside "reasonable" clock skew) it must be rejected.
  • iat (issued at time): The time at which the token has been issued. Must be before exp.
  • sub (subject): If applicable, used in user centric access control. This represents a unique identifier for the user.

Other non-standard claims (with some exceptions, see the claim mappings section) in the token are copied verbatim from the original token issued by idp (the original issuer of the subject token). For example, the claim used for the personal identifier (personidentifikator) for tokens issued by ID-porten is pid.

Claim Mappings

Some claims are mapped to a different value for legacy/compatibility reasons, depending on the original issuer (idp).

The table below shows the claim mappings:

Claim Original Value Mapped Value
acr idporten-loa-substantial Level3
acr idporten-loa-high Level4

This currently only affects tokens from ID-porten, i.e. idp= or idp=

The mappings will be removed at some point in the future. If you're using the acr claim in any way, check for both the original and mapped values.

Example Token (exchanged from ID-porten)

The following example shows the claims of a token issued by Tokendings, where the exchanged subject token is issued by ID-porten:

  "at_hash": "x6lQGCdbMX62p1VHeDsFBA",
  "sub": "HmjqfL7....",
  "amr": [
  "iss": "",
  "pid": "12345678910",
  "locale": "nb",
  "client_id": "prod-gcp:team-a:app-a",
  "sid": "DASgLATSjYTp__ylaVbskHy66zWiplQrGDAYahvwk1k",
  "aud": "prod-fss:team-b:app-b",
  "acr": "Level4",
  "nbf": 1597783152,
  "idp": "",
  "auth_time": 1611926877,
  "exp": 1597783452,
  "iat": 1597783152,
  "jti": "97f580a6-b479-426d-876b-267aa9848e2e"

Local Development

See also the development overview page.

Token Generator

In many cases, you want to locally develop and test against a secured API in the development environments. To do so, you need a token to access said API.

Use to generate tokens in the development environments.


  1. The API application must be configured with TokenX enabled.
  2. Pre-authorize the token generator service by adding it to the API application's access policy:
            - application: tokenx-token-generator
              namespace: aura
              cluster: dev-gcp

Getting a token

  1. Visit<audience> in your browser.
    • Replace <audience> with the intended audience of the token, in this case the API application.
    • The audience value must be on the form of <cluster>:<namespace>:<application>
    • For example: dev-gcp:aura:my-app
  2. You will be redirected to log in at ID-porten (if not already logged in).
  3. After logging in, you should be redirected back to the token generator and presented with a JSON response containing an access_token.
  4. Use the access_token as a Bearer token for calls to your API application.
  5. Success!