Workflow for PSD2 Accounts API

In this document, we will guide you through each step you need to take in order to access our PSD2 Accounts API.

All API calls here are made using mutually authenticated TLS.

References

Open Banking Security Profile

FAPI - FAPI Read-Only profile

FAPI-RW

OIDC Connect Core

MTLS

Terminology & abbreviations

  • TPP: the Third-Party Provider accessing the API.
  • Client App: an application developed by the TPP for accessing the API.

Prerequisites

Before you can start using our PSD2 APIs, ensure that you fulfill the requirements outlined in this section.

Sandbox

  • A registered app on OP Developer: API key and client secret
  • Certificates and related keypairs from our certificate generation API for mutually authenticated TLS
  • Successful registration via the TPP registration endpoint (incl. functional JWKS endpoints, redirect uris...)

In Test, the host addresses are the following:

ServiceHost
Authentication and authorizationhttps://authorize.psd2-sandbox.op.fi
Business APIs & token endpointshttps://mtls-apis.psd2-sandbox.op.fi
JWKS endpoint for ID token signature verificationhttps://authorize.psd2-sandbox.op.fi/mga/sps/oauth/oauth20/jwks/PSD2_OIDC (subject to change)

Production

  • Valid AISP/PISP registration and approval from a European financial authority, passported if necessary
  • Valid eIDAS certificates: QWAC for establishing MTLS, QSEAL for signing JWTs
  • Successful registration via the TPP registration endpoint (incl. functional JWKS endpoints, redirect uris...)

Overview

Sequence diagram for AIS

Succesfully using the PSD2 Account Information Service API requires completing the following steps:

  1. End user requests to access protected Account Information.
  2. Client App authenticates with Client Credentials Flow
  3. Client App POSTs to /authorizations to register intent
  4. End user authentication and authorization
  5. Client App receives an Authorization Code and possible ID token. Authorization code exchanged for an Access Token.
  6. TPP accesses the Accounts API using the access token.

Now we'll go over these steps one by one in detail.

1. End user requests access to protected Account Information

This step typically happens in the UI of the TPP application and is purely a matter between the TPP and the end user.

2. TPP application authenticates

To begin interacting with the account information service, the client application authenticates with the Oauth Client Credentials Flow using scope accounts. Note that any given request may only contain one scope.

The authentication request has the following format:

POST /oauth/v1/token HTTPS/1.1
Host: mtls-apis.psd2-sandbox.op.fi
Content-Type: application/x-www-form-urlencoded

grant_type=client_credentials&scope=accounts&client_id=<APP_CLIENT_ID>&client_secret=<APP_CLIENT_SECRET>

The following cURL call can be used for completing this step. The call assumes that your current directory contains your client certificate (client.crt) and the related private key (key.pem) - both are created by the [Registration Helper App].()

curl -vk --key key.pem --cert client.crt https://mtls-apis.psd2-sandbox.op.fi/oauth/token -d 'grant_type=client_credentials&scope=accounts&client_id=<client_id>&client_secret=<client_secret>'

If the request is successful, the will have the following content:

{
  "token_type" : "bearer",
  "access_token" : "Axqx362CnSmLABgzqcBasG0pxBj9",
  "scope" : "accounts",
  "status" : "approved",
  "expires_in" : "86399",
}

Save the access_token for use in the next step.

3. TPP registers intent to access Account Information

Now the TPP application is in possession of an access token. To advance, the TPP establishes mutually authenticated TLS with the host and uses the access token to make a POST call to the /authorizations endpoint. This registers the TPP's intent to access protected data.

Example call

curl -vk --key key.pem --cert client.crt https://mtls-apis.psd2-sandbox.op.fi/accounts-psd2/v1/authorizations \
-H 'x-api-key: 30VJGNf9QuRaLm1FL8HMgccKHyZaVPR7' \
-H 'Authorization: Bearer ecvAPboih8ff3xPVDFYJ' \
-H 'x-fapi-financial-id: test' \
-H 'Accept: application/json' \
-H 'Content-Type: application/json' \
-d '{"expires":"2019-03-14T11:24:13.889Z"}'  

Refer to the POST method on endpoint /authorizations in the API documentation of our Accounts API.

The response body will contain the field authorizationId. This identifies the account request and serves as the intent ID for this session.

4. Authentication and authorization

Authentication and authorization take place between the end user and the auth server of the account servicer. The role of the TPP is to prepare an appropriate JWT request, fill in the necessary query parameters, and redirect to the authorization address.

4.1 Preparing the JWT Request

The request is a JSON Web token that has been signed with a QSEALC private key (or a key which emulates QSEALC) using RS256 or ES256. The public key must be made available at a registered JWKS endpoint.

The header and payload of the JWT request have the following structure:

{
  "alg": "ES256",
  "typ": "JWT",
  "kid": "Vi3hb"
}
{
  "aud": "https://mtls.apis.op.fi",
  "iss": "1ztgnp8NZzUmlmiAdNoC",
  "response_type": "code id_token",
  "client_id": "1ztgnp8NZzUmlmiAdNoC",
  "redirect_uri": "https://localhost:8181/oauth/access_token",
  "scope": "openid accounts",
  "state": "37875a12-88e1-4f70-a347-de9270deecc4",
  "nonce": "64412183-b1c6-4fd1-9cd3-081f95ba1ce5",
  "max_age": 86400,
  "exp": 1549629139,
  "iat": 1549628239,
  "claims": {
    "userinfo": {
      "authorizationId": {
        "value": "28c52f98-7541-42a2-9ca0-b86ceac47692",
        "essential": true
      }
    },
    "id_token": {
      "authorizationId": {
        "value": "28c52f98-7541-42a2-9ca0-b86ceac47692",
        "essential": true
      },
      "acr": {
        "essential": true,
        "values": [
          "urn:openbanking:psd2:sca"
        ]
      }
    }
  }
}
<signature>
FieldTypeRequiredLegend
audstringtrueIntended audience of the JWT, i.e. the URL of the API.
issstringtrueIssuer of the token, i.e. Client ID of the TPP.
response_typestringtrueSpecifies the type of the authorization flow. Allowed values are code and code id_token .
client_idstringtrueUnique identifier of the client application.
redirect_uristringtrueThe address to which the end user wil be redirected after authentication and authorization. The access token or error descriptors will be attached to this uri as query parameters.
scopestringtrueScope names describing the extend of the requested authorization, as a list of space-separated names. For AIS, the default required value is "openid accounts". Only one of the following scopes is allowed for each request: accounts , payments , fundsconfirmations .
statestringtrueA string that will be returned to the TPP, for use in validating responses and correlating requests with responses.
noncestringtrueA unique string that is used for protecting against replay attacks. Generated by the Client App.
max_agenumberfalseMaximum allowed age for the authentication, in seconds.
expnumbertrueTime of expiry of the JWT request (Unix epoch, in seconds).
iatnumbertrueTime of issuance of the JWT request (Unix epoch, in seconds).
claimsobjecttrueContains information related to the request. The field authorizationId contains the authorizationId obtained while registering intent.
userinfoobjecttrueContains information related to the request. The field authorizationId contains the authorizationId obtained while registering intent.
id_tokenobjecttrueThe contents of this field are similar to userinfo.
acrobjtrueSpecifies the requested authorization contexts. Currently, the only allowed value is urn:openbanking:psd2:sca .

Once the body and header have been constructed, follow these steps: 1. Base64Urlencode the header and body separately. Append the body to the header, separating the two parts with a dot. 2. Create a signature by taking a copy of the newly created string and encrypting it with your private key (from QSEALC or emulated) using the algorithm specified in the header. This is the signature. 3. Attach the signature to the encoded header and body with a dot. You'll get something like this:

eyJhbGciOiJIUzI1NiJ9.eyJtc2ciOiJIZWxsbyJ9.N6-M8oOwCq9x820PR6HMtWo-_FL5GeWUSqQ66H2F5kA

Example code for signing JWTs

This code assumes that a file named ssa-signing-key.pem exists in the current directory. In sandbox, developers may use the Registration Helper App, which automatically generates this file.

import * as fs from 'fs';
import * as jwt from 'jsonwebtoken'; 

//claims is a valid pre-created JWT body
const asymmetricSign = (claims: object) => {
  const algorithm = 'ES256';
  const signCert = fs.readFileSync(`./ssa-signing-key.pem`, 'ascii');
  const jwtOptions = {
    header: {
      typ: 'JWT',
      kid: 'BSyrDg'
    },
    algorithm
  };
  return jwt.sign(JSON.stringify(claims), signCert, jwtOptions);
};

Learn more about JWTs on jwt.io. Note that the JWT editor is currently incapable of processing this type of key.

4.2 Redirection

Once the request is complete, the TPP will redirect the customer to OP's auth server. The client app must append the following query parameters to the redirection URI:

  • request (the JWT request)
  • response_type
  • client_id
  • scope

The values of the parameters MUST match those in the JWT request. Remember that all query parameters must be URLencoded.

The redirect will have the following structure:

https://authorize.psd2-sandbox.op.fi/oauth/authorize
?request=<your_JWT_string>
&response_type=code
&client_id=******
&scope=openid%20accounts

4.3 The customer authenticates and authorizes

Authentication and authorization are the business of the customer and the auth server. The customer logs in, selects the authorizations they wish to consent to, and approves or rejects them.

4.4 Back to Client Application

The auth server will redirect the end user to the redirect URI specified in the request. There are two possible outcomes:

Success:
<REDIRECT_URI>?state=<state>&code=<authorization_code>

Success with ID token:
<REDIRECT_URI>#state=<state>&code=<authorization_code>&id_token=<id_token>

Error:
<REDIRECT_URI>?state=<state>&error=<error_description>

For example:
https://localhost:8181/oauth/access_token?error=temporarily_unavailable&state=373b23cd-a1b3-449a-810f-cd4b36f7a60c

ID tokens are created and returned on two occasions:

  1. When using response type code id_token in the authorization request. The id token will be delivered in a query parameter attached to the client app's redirect URI. Note that when an ID token is present, the query string is in fact an URI fragment (begins with "#" instead of "?").
  2. When requesting a token from a token endpoint and scope includes openid (in OP PSD2, always). The token will be returned in the response body to the token request.

The ID token contains information about the authorization, and provides an additional layer of security.

The ID token contains the following information:

{
  "typ": "JWT",
  "alg": "RS256",
  "kid": "12345"
}
.
{
  "iss": "https://authorize.psd2-sandbox.op.fi",
  "iat": 1234569795,
  "sub": "28c52f98-7541-42a2-9ca0-b86ceac47692",
  "acr": "urn:openbanking:psd2:sca",
  "authorizationId": "28c52f98-7541-42a2-9ca0-b86ceac47692,
  "aud": "s6BhdRkqt3",
  "nonce": "n-0S6_WzA2Mj",
  "exp": 1311281970,
  --ALTERNATIVE 1: AUTHORIZATION CODE FLOW---
  "s_hash": "76sa5dd",
  "c_hash": "asd097d"
  --ALTERNATIVE 2: TOKEN ENDPOINT---
  "rt_hash": "wFsWWP49hHo4sXwwVSHX-A",
  "at_hash": "bSUTLJiqrooANhJJ2X7pPw"
  }
.
{
<<signature>>
}
FieldTypeLegend
issstring/URIIssuer of the token.
iattimestampToken issuance time as seconds since 1970-01-01T0:0:0Z.
substringThe authorizationId to which the ID token relates to.
acrstringAuthentication Context Class Reference, i.e. field that describes the level of authentication achieved. Currently, only urn:openbanking:psd2:sca is supported.
authorizationIdstringThe authorizationId to which the ID token relates to.
audstring/client IDIntended audience of the ID token. WIll contain the Client Id of the Client Application.
noncestringA value originally provided by the TPP in the request, used for protecting against replay attacks.
exptimestampTime of expiry, i.e. the time after which the token is no longer valid.
s_hashstring, case-sensitiveReturned with authorization code. State hash value: base64Url encoding of the left-most half of the hash of the octets of the ASCII representation of the state value, where the hash algorithm used is the hash algorithm used in the algHeader Parameter of the ID Token's JOSE Header. For instance, if the alg is RS256, hash the code value with SHA-256, then take the left-most 256 bits and base64url encode them. The s_hashvalue is a case sensitive string.
c_hashstring, case-sensitiveReturned with authorization code. Code hash value: base64url encoding of the left-most half of the hash of the octets of the ASCII representation of the code value, where the hash algorithm used is the hash algorithm used in the alg Header Parameter of the ID Token's JOSE Header.
rt_hashstringReturned from token endpoint. Refresh token hash value: base64url encoding of the left-most half of the hash of the octets of the ASCII representation of the refresh_token value, where the hash algorithm used is the hash algorithm used in the alg Header Parameter of the ID Token's JOSE Header. For instance, if the alg is RS256, hash the refresh_token value with SHA-256, then take the left-most 128 bits and base64url encode them. The rt_hash value is a case sensitive string.
at_hashstringReturned from token endpoint. Authorization token hash value: base64url encoding of the left-most half of the hash of the octets of the ASCII representation of the access_token value, where the hash algorithm used is the hash algorithm used in the alg Header Parameter of the ID Token's JOSE Header. For instance, if the alg is RS256, hash the access_token value with SHA-256, then take the left-most 128 bits and base64url encode them. The at_hash value is a case sensitive string.

The ID token must be validated following the OIDC spec. In addition, the TPP should do the following:

Alternative 1: ID token received in redirection URI

  • Validate the authorizationId against that received earlier
  • Validate the signature of the ID token
  • Validate s_hash (state validation)
  • Validate c_hash (code validation).

Alternative 2: ID token in access token response body

  • Validate the authorizationId against that received earlier
  • Validate the signature of the ID token
  • Validate s_hash (state validation)
  • Validate c_hash (code validation).

The public key for validating ID token signatures is available at https://authorize.psd2-sandbox.op.fi/mga/sps/oauth/oauth20/jwks/PSD2_OIDC.

5. Token exchange

At this point the TPP is in possession of an authorization code. Thus must now be exchanged for an access token with a POST call of the following type:

POST /oauth/token HTTPS/1.1
Host: mtls-apis.psd2-sandbox.op.fi
Content-Type: application/x-www-form-urlencoded

grant_type=authorization_code&code=<code>&redirect_uri=<redirect_uri>&client_id=<APP_CLIENT_ID>&client_secret=<APP_CLIENT_SECRET>

cURL:

curl -vk --key key.pem --cert client.crt https://mtls-apis.psd2-sandbox.op.fi/oauth/token -d 'grant_type=authorization_code&client_id=VxEjWZCQ98ngGN0imOOd&client_secret=WOf1v30GGeJq7MZL6FXs&code=wpj94iuZRzFvmHHpIFba7b1QiZweXm&redirect_uri=https%3A%2F%2Flocalhost%3A8181'

A successful request will yield a response with the following content:

{
  "access_token":"TfOJ0yOywdg8cwthvKUE",
  "refresh_token":"TYiOBpLHMWSgXsTg0SJ7TlqVMhSsWnJ6vxL6dUk9",
  "id_token": "eyJraWQiOiI2ZzNRRU9SY0hNOVdVZTZlcVowZi1wdjNEUEV1Y2NHVTRUdDFVMHo0cFIwIiwiYWxnIjoiUlMyNTYifQ.eyJydF9oYXNoIjoiMDJaODNSbVFqbTYtQWJEYXRkLTBIdyIsIm5vbmNlIjoiMTIzNCIsImF1dGhvcml6YXRpb25JZCI6ImMxMzgxMDM1LTU2OGMtNGUzYS04OGM5LTQ1Mzk2ZTU2OTBlMiIsImlhdCI6MTU1MjQ3NDkyNSwiaXNzIjoiaHR0cHM6Ly9hdXRob3JpemUua2VoaS5vcC1wYWx2ZWx1dC5uZXQiLCJhdF9oYXNoIjoidmU0MnhDS2ExOTJ4MnplV00zaE5wdyIsInN1YiI6InVpZDUwMDczNTA5IiwiZXhwIjoxNTUyNDc4MjI1LCJhY3IiOiJ1cm46b3BlbmJhbmtpbmc6cHNkMjpzY2EiLCJhdWQiOiJPUF90ZXN0X2NsaWVudCJ9.OMxF_fyVTS0af_so533ODdbbVfw3DOHZmzR-Yosl1N8df6zNZ6FIvFt8PjhcNBG2cMUyAIvfwpt9hKcMt0zwtccyVJzUPPL-ArVuiMIysjJiWo5pp_0AyRaeB-ThqlzMG0yBMibILUobOaZJqNZb1fodE6u_eHEjD2kUEHuxCglIGs8Zu47rhXnSY044YUsukhY1XgThmDPXd0T4vZsmfh_1dDGgp5TX6disKXh1ltspukqnimtI8uf9RrihE5QHu83slodFepHXzYBdlr63wOB15QLvVJXJtZgoM9QUmsAlh9efCEvgGGMcVtB04UEfkGWRQye9sQXEGMHW_S7bsA",
  "scope":"openid accounts",
  "token_type":"bearer",
  "expires_in":3599,
}
FieldtypeLegend
access_tokenstringThis is the access token. Use as a bearer token in the Authorization header to access protected resources.
refresh_tokenstringCan be used to request additional access tokens.
id_tokenstringA signed JWT containing information about the authorization. See ID tokens for a full description on the contents and recommended validation procedures for ID tokens.
scopestringA space-separated list of scope names describing the services to which the token grants authorization.
token_typestringToken type. Always has the value "bearer".
expires_innumberThe period for which the token is valid, in seconds.

Refreshing

The Client App may request additional access tokens with the refresh token. The request has the following structure:

POST /oauth/token HTTPS/1.1
Host: mtls-apis.psd2-sandbox.op.fi
Content-Type: application/x-www-form-urlencoded

grant_type=refresh_token&refresh_token=<refresh_token>&client_id=<APP_CLIENT_ID>&client_secret=<APP_CLIENT_SECRET>

The response body to this request is identical to that of a normal token request.

6. API Access

Finally, the TPP application can access protected account information using the bearer token acquired in step 5. See the API Documentation for full details.

GET /accounts-psd2/v1/accounts HTTPS/1.1
Host: sandbox.apis.op-palvelut.fi
Accept: application/json
x-api-key: <APP_API_KEY>
Authorization: Bearer <authorization>
x-fapi-interaction-id: <UUID>
x-customer-user-agent: <user_agent>
x-fapi-customer-ip-address: <ip_address>