OpenID Connect Client-Initiated Backchannel Authentication (CIBA)

BankID with biometrics supports CIBA for certain use cases. Get in touch to discuss your use case and enable CIBA for your client.

All permissions needs to be registered upfront

When authenticating with CIBA the permission needs to be registered upfront. This is explained in the steps below.

Steps

• 1. Register a client with BankID OIDC
• 2. Get the BankID OpenID Connect Configuration
• 3. Get an access token from BankID OIDC
• 4. Get the BankID with biometrics OIDC configuration
• 5. Check if user is able to authenticate with CIBA
• 6. Register the permission upfront
• 7. Initiate backchannel request
• 8. Poll for the result
• 9. Validate the ID token
• 10. Get the signed permission (optional)

1. Register a client with BankID OIDC

If you don't have a client registered with BankID OIDC yet, you'll need to register one. Follow the instructions here to register your application and obtain the necessary client credentials (client_id and client_secret). You will need two clients, one for the test environment and one for the production environment.

Ensure that your client has the permissions/client and permissions/ciba scopes available.

For testing the CIBA flow in the test environment, you will need to register a test user and get access to the BankID preprod app. Detailed instructions on how to do this can be found in the testing document.

2. Get the BankID OpenID Connect Configuration

To ensure seamless integration with BankID OIDC and avoid hardcoding specific endpoints in you application, follow these steps to dynamically fetch the OpenID Connect configuration:

1. Determine the appropriate configuration URL based on the environment:

   Environment	Url
   Production	https://auth.bankid.no/auth/realms/prod/.well-known/openid-configuration
   Current (public test environment)	https://auth.current.bankid.no/auth/realms/current/.well-known/openid-configuration

2. Send an HTTP GET request to the respective configuration URL using your preferred programming language or API tool.

3. Capture the response which will contain a JSON document with the configuration. By dynamically fetching the OIDC configuration, your application remains flexible, allowing for future changes or updates to the endpoints without requiring modifications to your code.

Example response from Current (relevant fields only)

{
  ...
  "token_endpoint": "https://auth.current.bankid.no/auth/realms/current/protocol/openid-connect/token",
  ...
}

This is a sample response. The actual response may differ.

3. Get an access token from BankID OIDC

To obtain an access token from OIDC, follow these steps:

1. Retrieve the token endpoint URL token_endpoint dynamically from the OIDC configuration.

2. Call the token endpoint URL with your client credentials.

   You can find more detailed information about acquiring access tokens in the BankID OIDC documentation.

3. In the scope field, include the following: permissions/client, and permissions/ciba. This field specifies the scope of access granted to the token.

Here's an example of a valid request in the current environment:

POST /auth/realms/current/protocol/openid-connect/token HTTP/1.1
Host: auth.current.bankid.no
Content-Type: application/x-www-form-urlencoded
Authorization: Basic <Base64-encoded client id:client secret>

grant_type=client_credentials&scope=permissions%2Fclient%20permissions%2Fciba

Make sure to replace the <Base64-encoded client id:client secret> placeholder in the Authorization header with your actual client credentials.

4. Get the BankID with biometrics OIDC configuration

To ensure seamless integration and avoid hardcoding specific endpoints in you application, follow these steps to dynamically fetch the OpenID Connect configuration:

1. Determine the appropriate configuration URL based on the environment:

   Environment	Url
   Production	https://app.bankid.no/.well-known/openid-configuration
   Current (public test environment)	https://current.aletheia-test.idtech.no/.well-known/openid-configuration

2. Send an HTTP GET request to the respective configuration URL using your preferred programming language or API tool.

3. Capture the response which will contain a JSON document with the configuration. By dynamically fetching the OIDC configuration, your application remains flexible, allowing for future changes or updates to the endpoints without requiring modifications to your code.
4. To enhance the reliability and performance of your integration, we strongly advise implementing response caching for the OIDC configuration.

5. Check if user is able to authenticate with CIBA

To be able to authenticate with CIBA, the user must be enrolled in BankID with biometrics. To check if the user is enrolled, you need to make a request to the user-exists API.

6. Register the permission upfront

To register a permission, follow these steps:

1. Construct a permission statement. See the permissions API for detailed information of how to construct the different permissions. Encode the permission statement using URL safe Base64 encoding. Below is an example of a permission statement for a payment:

   const permissionStatement = {
       "nonce": "dW5pcXVlIHZhbHVl", // Must be unique
       "id": "YmFza2V0IGlk", // Your reference
       "payments": [
           {
               "paymentId": "cGF5bWVudCBpZA", // Your reference
               "amount": "123.45",
               "currency": "NOK",
               "creditorName": "Scrooge McDuck"
           }
       ]
   }
   
   // Example implementation of a b64 URL Safe Encoder
   function b64URLSafeEncode(stringData) {
       return btoa(stringData)
           .replace(/\+/g, "-")
           .replace(/\//g, "_")
           .replace(/=/g, "");
   }
   
   b64URLSafeEncode(
       JSON.stringify(
           permissionStatement
       )
   );
   // -> "eyJub25jZSI6ImRXNXBjWFZsSUhaaGJIVmwiLCJpZCI6IlltRnphMlYwSUdsayIsInBheW1lbnRzIjpbeyJwYXltZW50SWQiOiJjR0Y1YldWdWRDQnBaQSIsImFtb3VudCI6IjEyMy40NSIsImN1cnJlbmN5IjoiTk9LIiwiY3JlZGl0b3JOYW1lIjoiU2Nyb29nZSBNY0R1Y2sifV19"
   

   Note

   • The nonce must be a unique value for each permission you register.
   • Use id (basket ID) and paymentId as references to the payment(s) in your systems. These will not be shown to the end user.
   • The amount is a decimal amount represented as a string and must use the dot as the decimal separator.

2. Send a POST request to the permissions endpoint, providing the access token received in the first step as a bearer token. Include the permission, which is the URL safe Base64 encoding of the permission statement object.

   POST /permissions/v1/ HTTP/1.1
   Host: api.current.aletheia-test.idtech.no
   Content-Type: application/json
   Authorization: Bearer <access token from step 1>
   
   {
     "type": "payment.v1",
     "iat": 1617091752,
     "exp": 1617092652,
     "permission": < URL safe b64 encoded permission statement from step 2a >,
     "intents": [
       "ciba"
     ],
     "loginHint": [
       {
         "scheme": "nnin",
         "value": "<nnin_as_string>"
       }
     ]
   }
   

   Note

   • iat and exp are timestamps in seconds since the UNIX epoch. iat can be at most 1 minute into the past. exp sets the maximum time by which the permission must be granted and should normally be set just a few minutes into the future.
   • When using intents : ["ciba"] it is mandatory to include loginHint in the request.

3. On a successful request, you will receive a response body containing a permission ID, a permission token and a binding message:

   {
     "id": "1.BY.MEKrA-00GVtmvWOCDYQko_fSg93LO5n2rBnlj-X4MQg.BiDEl_CgfakqahcXjLrFet_GGpEkR_W8D-RK4hORBO0",
     "permissionToken": "eyJhbGciOiJIUzI1NiIsImtpZCI6IjB5Z3hDX3UzQlpPWXlKZ0Y3eDJ0eWtQaTRCTml2cG9KMDBmYjFzTGliUVUiLCJ0eXAiOiJKV1QifQ.eyJleHAiOjE2MTcwOTU3NDQsImlhdCI6MTYxNzA5MjE0NCwicyI6IjA6LTEjOTIzIiwicCI6IkJpREVsX0NnZmFrcWFoY1hqTHJGZXRfR0dwRWtSX1c4RC1SSzRoT1JCTzAiLCJuYmYiOjE2MTcwOTIxNDh9.39GWvNjNMSKKhKOF4t4HcDnZGNJmLmPT3f612z1VKko",
     "bindingMessage":"Farlig frakk"
   }
   

7. Initiate backchannel request

Make a POST request to the bc-authorize endpoint, including the the permissionToken from step 3 as the login_hint_token to the bc-authorize endpoint.

Expand the below list below on which scopes to include (space-separated).

Scopes

The openid scope is always required.

profile: Gets the user's profile information

Returned Claims:

• name
• given_name
• family_name
• birthdate
• updated_at

sub_nnin: Gets the user's national identity number (NNIN).

The sub_nnin scope is only available for clients with explicit access!

Returned claims:

• sub_nnin

sub_bankid: Gets the the user's BankID PID.

Returned claims:

• sub_bankid

Passing access token as Bearer token:

POST /oidc/v1/token HTTP/1.1
Host: oidc.current.aletheia-test.idtech.no
Content-Type: application/x-www-form-urlencoded
Authorization: Bearer <access token from client credentials exchange>

login_hint_token=<permission token from step 3>
&binding_message=<binding message from step 3>
&scope=openid%20sub_bankid

Passing access token as client_assertion form value:

POST /oidc/v1/token HTTP/1.1
Host: oidc.current.aletheia-test.idtech.no
Content-Type: application/x-www-form-urlencoded

client_assertion=<access token from client credentials exchange>
&client_assertion_type=urn%3Aietf%3Aparams%3Aoauth%3Aclient-assertion-type%3Ajwt-bearer
&login_hint_token=<permission token from step 3>
&binding_message=<binding message from step 3>
&scope=openid%20sub_bankid

Note: Replace string with the actual login_hint_token and provide appropriate values for other fields.

After calling the bc-authorize endpoint, you will receive the following response:

{
  "auth_req_id": "stringstring",
  "expires_in": 0,
  "interval": 0
}

The bc-authorize endpoint returns auth_req_id which you will use when posting a request to the token endpoint afterwards.

8. Poll for the result

1. Make a POST request to the token endpoint using the CibaTokenRequest schema. You may call call this endpoint every interval seconds, as specified in the response from the previous step.

   Passing access token as Bearer token:

   POST /oidc/v1/token HTTP/1.1
   Host: oidc.current.aletheia-test.idtech.no
   Content-Type: application/x-www-form-urlencoded
   Authorization: Bearer <access token from client credentials exchange>
   
   grant_type=urn%3Aopenid%3Aparams%3Agrant-type%3Aciba
   &auth_req_id=<auth_req_id from step 7>
   

   Passing access token as client_assertion form value:

   POST /oidc/v1/token HTTP/1.1
   Host: oidc.current.aletheia-test.idtech.no
   Content-Type: application/x-www-form-urlencoded
   
   client_assertion=<access token from client credentials exchange>
   &client_assertion_type=urn%3Aietf%3Aparams%3Aoauth%3Aclient-assertion-type%3Ajwt-bearer
   &grant_type=urn%3Aopenid%3Aparams%3Agrant-type%3Aciba
   &auth_req_id=<auth_req_id from step 7>
   

   Note: Replace string with the actual values, including the auth_req_id.

2. While the user haven't completed the authentication yet the token endpoint will respond with a 400 authorization_pending error.

   {
     "error": "authorization_pending",
     "error_description": "User has not yet granted authorization"
   }
   

3. Keep polling this endpoint until you get a different error with a 400 response, or a 200 response with the id_token in the response body.

   Here's an example of a successful response:

   {
     "token_type": "string",
     "expires_in": 0,
     "id_token": "string"
   }
   

   And here's an example of an errored response:

   {
     "error": "access_denied",
     "error_description": "Authorization was denied by the user"
   }
   

9. Validate the ID token

To ensure the authenticity and integrity of the received ID token, you must perform the following verification:

• Verify that the token is signed by a key from our JWKS (JSON Web Key Set) Document. The URI for the JWKS document can be found under the jwks_uri key in the BankID with biometrics OIDC configuration document you retrieved in step 4. You must also verify that the algorithm used is found in the BankID with biometrics OIDC configuration under id_token_signing_alg_values_supported.

We recommend verifying these additional properties:

• iss (issuer) - The issuer of the token must match the issuer in the BankID with biometrics OIDC configuration.
• aud (audience) - The audience of the token must match your client ID.
• exp (expiration time) - The token must not be expired.
• iat (issued at) - The token must not be issued in the future.
• acr (authentication context class reference) is only relevant if you've asked for forced step up. If relevant must be verified to be the expected value.

Further information on how to validate the ID token can be found in the OpenID Connect Core specification.

10. Get the signed permission (optional)

To get the signed permission you can send in a GET request to the permissionId/grant endpoint. The permissionId you use is the one that you got from your permissions POST request. Be aware that it can return a 404 error code (permission not yet granted) but as mentioned in the api specification you can set up a polling request on the permissionId/grant endpoint until your initial permission has been signed.

If your permission has been successfully granted you will receive this response:

{
  "gv": 1,
  "pt": "string",
  "type": "string",
  "rpId": "bankid-app",
  "sv": "2020-10-30@deadbeef",
  "iat": 1800000000,
  "iss": "string",
  "nonce": "string",
  "proofKeyId": "string",
  "sub": "nnin:010112345",
  "permissionId": "string",
  "digest": "string"
}

The grant is a JWT that can be validated as follows:

• In the BankID with biometrics OIDC configuration (as mentioned here) get the Grant JWK set from the URI pointed to by the jwks_uri_grants property in this document.
• Check that the JWT is signed by one of the keys in the Grant JWK set. You can find a suitable library for performing this verification at https://jwt.io/libraries.
• Check that the nonce claim inside the token payload is equal to the nonce in the permission statement created in step 2.