Version Control

Introduction

This specification defines two mechanisms by which a Primary Technical Contact (PTC) for a Trusted Third Party (TPP) may submit a Software Statement Assertion (SSA) to an Account Servicing Payment Services Provider (ASPSP) for the purposes of receiving a client credential enabling access to UK OpenBanking APIs on behalf of ASPSP Customers. The automated mechanism profiles [RFC7591]. The manual mechanism uses web single sign-on for secure access by the PTC to a portal operated by the ASPSP that is based on the original PTC credentials used to generate the SSA.

Terminology

This specification uses the terms "access token", "authorization code", "authorization endpoint", "authorization grant", "authorization server", "client", "client identifier", "client secret", "grant type", "protected resource", "redirection URI", "refresh token", "resource owner", "resource server", "response type", and "token endpoint" defined by OAuth 2.0 [RFC6749] and uses the term "Claim" defined by JSON Web Token (JWT) [RFC7519].

...

TPP Client Software - software implementing an OAuth2 client, interacting with an ASPSP registration endpoint.

Software Statement Assertion (SSA)

The SSA is a JSON Web Token (JWT) containing client metadata about an instance of TPP client software. The JWT is issued and signed by the OpenBanking Directory.

A large number of claims that OpenID Connect OPs could support are detailed https://openid.net/specs/openid-connect-registration-1_0.html#ClientMetadata and should be followed if not explicitly referenced below.

SSA Payload

The payload of an OpenBanking SSA MUST be a compliant software statement according to [RFC7591]. The SSA MUST also be a compliant JWT according to [RFC7519]. The following metadata profiles the metadata in [RFC7591] and [RFC7519]:

...

SSA header

The SSA header MUST comply with [RFC7519].

Example SSA

The elements defined in the software statement will consist of the following values.

...

{
    "typ": "JWT",
    "alg": "ES256",
    "kid": "ABCD1234"
}
{
    "iss": "OpenBanking Ltd",
    "iat": 1492756331,
    "jti": "id12345685439487678",
    "software_environment": "production",
    "software_mode": "live",
    "software_id": "65d1f27c-4aea-4549-9c21-60e495a7a86f",
    "software_client_id": "OpenBanking TPP Client Unique ID",
    "software_client_name": "Amazon Prime Movies",
    "software_client_description": "Amazon Prime Movies is a moving streaming service",
    "software_version": "2.2",
    "software_client_uri": "https://prime.amazon.com",
    "software_redirect_uris":
    [
        "https://prime.amazon.com/cb",
        "https://prime.amazon.co.uk/cb"
    ],
    "software_roles": [
        "PISP",
        "AISP"
    ],
    "organisation_competent_authority_claims": [
      {
        "authority_id": "FMA", // Austrian Financial Market Authority
        "registration_id": "111111",
        "status": "Active",
        "authorisations":  [
                {
                    "member_state": "GBR",
                        "roles": [
                            "PISP",
                            "AISP"
                    ]
                },
                {
                    "member_state": "ROI",
                        "roles": [
                            "PISP"
                    ]
                }
            ]
      }
    ],

    "software_logo_uri": "https://prime.amazon.com/logo.png",
    "org_status": "Active",
    "org_id": "Amazon TPPID",
    "org_name": "OpenBanking TPP Registered Name",
    "org_contacts": [
      {
        "name": "contact name",
        "email": "contact@contact.com",
        "phone": "+447890130558"
        "type": "business"
      },
      {
        "name": "contact name",
        "email": "contact@contact.com",
        "phone": "+447890130558",
        "type": "technical"
      }
    ],
    "org_jwks_endpoint": "https://jwks.openbanking.org.uk/org_id/org_id.jkws",
    "org_jwks_revoked_endpoint": "https://jwks.openbanking.org.uk/org_id/revoked/org_id.jkws",
    "software_jwks_endpoint": "https://jwks.openbanking.org.uk/org_id/software_id.jkws",
    "software_jwks_revoked_endpoint": "https://jwks.openbanking.org.uk/org_id/revoked/software_id.jkws",
    "software_policy_uri": "https://tpp.com/policy.html",
    "software_tos_uri": "https://tpp.com/tos.html",
    "software_on_behalf_of_org": "https://api.openbanking.org.uk/scim2/OBTrustedPaymentParty/1234567789",
    "ob_registry_tos": "https://registry.openbanking.org.uk/tos.html"

}
{
    Signature
}

Automated Client Registration

A TPP MAY use automated client registration to submit an SSA to an ASPSP in exchange for client credentials for use as a client against an OAuth 2.0 Authorization Server. It is RECOMMENDED for ASPSPs to support the automated client registration mechanism.

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The TPP must only present the SSA to an ASPSP over a mutually authenticated TLS channel using a certificate issued by the OB. In this case, the combination of possession of the SSA, the possession of private keys referenced in the SSA and ability to present it over a channel that can be validated as belonging to the same TPP organization, is a strong barrier for attackers. Unlike RFC7591 the client registration request will be of type JWT where the registration request itself is a signed jwt.

Client Registration Endpoint

If an ASPSP supports automated client registration, the ASPSP MUST operate an [RFC7591] compliant registration endpoint. The client registration endpoint MUST be protected by transport-layer security (TLS 1.2 or better) The transport layer MUST be mutually authenticated using certificates chaining to the OpenBanking certificate authority The ASPSP registration endpoint MUST accept HTTP POST messages with request parameters encoded in the entity body using the "application/jwt" content-type. The ASPSP registration endpoint SHOULD accept registration attempts from any mutually authenticated channel whose certificate chains to the OpenBanking certificate authority and is not revoked.

Request Validation

Prior to issuing a client registration response, the ASPSP MUST perform the following checks The ASPSP SHOULD check whether the TPP that initiated the TLS connection is the same TPP as listed in the SSA. In the case where a gateway or other piece of infrastructure pre-terminates the MATLS channel in front of the registration endpoint, the certificate used to initiate the connection or some part of that certificate (such as DN & Issuer) SHOULD be made available to the ASPSP for validation against the claims in the SSA. The registration request MUST be signed with a key contained in the JWKS referenced in the SSA included with the request. This ensures that a holder-of-key proof-of-possession is performed proving that the TPP app was the originally intended recipient of the SSA when the OB issued it. The SSA MUST be validated according to [RFC7519], including validation of the signature and validity window.

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• SSA Lifetime

• The SSA's Lifetime will be short, typically less than 10 minutes. TPPs will be able to retrieve SSAs from OB using client_credentials grant so there should be no need for a SSA to be long lived.

Supported extensions to RFC7591

Section for the support sections / profile enhancements on RFC7591 e.g OIDC client reg profile, reg profile enhancments for mtls token end point auth

Client Registration Request

To register as a client at an ASPSP, the TPP sends an HTTP POST to the ASPSP registration endpoint. The request MUST be presented in the format of a [RFC7519] compliant JWT. The request MUST use the HTTP POST method, using the application/jwt method. * The JWT MUST be signed using algorithms specified in [FAPI-RW] Section 8.6.

Request Claims

The client registration request MUST contain the following claims in the JWT payload unless designated as Optional. The TPP MAY add additional claims to the JWT payload. The ASPSP MAY ignore claims not in the chart below. If a claim name matches a specified claim in any of [RFC7519], [RFC7591], or [FAPI], the usage must also match the specification.

SUPPORTED TOKEN ENDPOINT AUTHENTICATION METHODS

The TPP MUST choose one of the following token endpoint authentication methods:

...

HTTP POST Client Authentication A TPP choosing to use HTTP Basic Authentication method MUST set the token_endpoint_auth_method claim in the registration request to client_secret_post as per [rfc6749] section 2.3.1.

SUPPORTED GRANT TYPES

The TPP MUST specify one or more of the following values in the grant_types claim. Values MUST be encoded as a JSON array. ASPSPs MAY reject anything other than client_credentialsor authorization_code. authorization_code refresh_token * client_credentials

SUPPORTED RESPONSE TYPES

A TPP MAY specify response_types in the request. Values MUST be encoded as a JSON array. In the case this value is omitted, and any grant type that utilizes the authorisation endpoint is also specified, the default response_types array contains the single value of code. ASPSPs SHOULD support code id_token and MAY support code.
Supported response_types include: code code id_token

Supported Request URIs

The TPP MAY specify a JSON array of [RFC3986] compliant redirect URIs in the request using the redirect_uris metadata element. Every value in the redirect_uris JSON array MUST adhere to the following rules: * The URI MUST use the https scheme * The URI MUST NOT contain a host with a value of localhost * The URI MUST exactly match a URI within the software_redirect_uris element of the SSA as described in Section 6.2.1 of [RFC3986] (Simple String Comparison). If the request_uris metadata element is omitted from the request, the entire contents of the software_redirect_uris element in the SSA are considered to be requested by the TPP.

Example Request

POST /register HTTP/1.1
Content-Type: application/jwt
Accept: application/json
Host: auth.bankone.com

eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJJREFtYXpvbiIsImlhdCI6MTQ5OTgwNTg0OCwiZXhwIjoxNTMxMzQxODQ4LCJhdWQiOiJodHRwczovL2F1dGhuLmxsb3lkc2JhbmsuY29tIiwic3ViIjoiaHR0cHM6Ly9hdXRobi5sbG95ZHNiYW5rLmNvbSIsImNsaWVudF9pZCI6IklEQW1hem9uMSIsInNvZnR3YXJlX3N0YXRlbWVudCI6ImV5SjBlWEFpT2lKS1YxUWlMQ0poYkdjaU9pSklVekkxTmlKOS5leUpwYzNNaU9pSlBjR1Z1UW1GdWEybHVaeUlzSW1saGRDSTZNVFE1T1Rnd05UZzBPQ3dpWlhod0lqb3hOVE14TXpReE9EUTRMQ0poZFdRaU9pSkZlR0Z0Y0d4bElGUlFVQ0lzSW5OMVlpSTZJa1Y0WVcxd2JHVWdWRkJRSWl3aVQySlVVRkJKWkNJNklrbEVRVzFoZW05dUlpd2lUMkpVVUZCU2IyeGxJam9pVUVsVFVDSjkuUnJydEpYbmZmSzVjOHJJeEczUm93QXNRZWNlSDNvWlFXTWJwZ0hENzhPOCJ9.VRckIjwgB9ahNTPK6GcDzCfqbU9mkvoOu-B_2jHdKzs

Example Decoded Registration Request (Non Normative JWT decoded For Illustration)

POST /register HTTP/1.1
     Content-Type: application/jwt
     Accept: application/json
     Host: authn.lloyds.co.uk
{
    "typ": "JWT",
    "alg": "ES256",
    "kid": "ABCD1234"
}
{
    "iss": "Amazon TPPID",
    "iat": 1492760444,
    "exp": 1524296444,
    "aud": "https://authn.lloyds.co.uk",
    "scope": "openid makepayment",
    "token_endpoint_auth_method": "private_key_jwt",
    "grant_types": ["authorization_code", "refresh_token", "client_credentials"],
    "response_types": ["code"],
    "id_token_signed_response_alg": "ES256",
    "request_object_signing_alg": "ES256",
    "software_id": "65d1f27c-4aea-4549-9c21-60e495a7a86f",
    "software_statement":     "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzUxMiJ9.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.dtWXOW7uAc-jM_-wZNyNvN3dkgd4yV6KkdS_6rbNRUBD15_rWO1FARF7WcjFmSvlZZrT-njf9CmJKbhl7DuXIw"
}
{
    Signature
}

...

• OPs MAY NOT support optional values listed below that are asserted by the TPP.
• OPs MAY NOT adopt values asserted by the TPP that are also contained in the software statement
• OPs SHALL reject requests if the requested configuration is not supported by the OP. e.g token_endpoint_auth_method requested should match one listed on the well-known configuration endpoint.

Registration Request Validation

An ASPSP MUST return an error response if any of the following requirements are not met: - The registration request assertion MUST contain a software statement attribute as client metadata. - The signature of the software statement assertion MUST validate against the OpenBanking JWKS or JWKS URI distributed and validated out of band of the current registration request - The signature of the registration request assertion MUST successfully validate against the JWKS URI specified in the software_jwks_endpoint attribute of the software statement assertion (SSA). - If the request assertion specifies a redirect_uris metadata element, the array contents MUST match or be a subset of the software_redirect_uris claim in the SSA. - If the request assertion specifies a software_id metadata element, that value MUST match the software_id element in the SSA.

Certificate Based TLS Validation

As described in [RFC7515] section 4.1.4 all OpenBanking Ltd ecosystem certificates will be issued as X.509 certificates that can be uniquely identified in a JWKS key store by the keyid. The format of the keyid will be aligned to the x5t parameter of the certificate from which the key is extracted as documented in [RFC7515] section 4.1.8.

...

• The transport layer negotiated by the TPP MUST be mutually authenticated.
• The client TLS certificate SHOULD chain to a certificate located in the SSA 'org_jwks_endpoint' attribute.
• The client TLS certificate must contain the following attributes:
• The Subject DN MUST contain the commonName (CN) attribute and organisationUnit (OU) of the certificate.
• The CN attribute of the certificate MUST match the software_id specified within the SSA.
• The OU attribute of the certificate MUST match the org_id specified within the SSA.
• The Issuer DN MUST be validated ensuring that the issuer was the appropriate Open Banking CA for the environment.

Client Registration Response

At the time that the ASPSP finishes evaluation of the request, the ASPSP MUST return a client registration response to the TPP that reflects the final ASPSP client onboarding decision.

Successful Client Registration Response

In the case where the ASPSP makes a positive determination and creates a client, a Client Information Response MUST be returned to the the TPP conforming to Section 3.2.1 of [RFC7591]. The parameters returned in the response will vary depending on which token endpoint authentication method was specified in the request.

EXAMPLE CLIENT REGISTRATION RESPONSE

HTTP/1.1 201 Created
     Content-Type: application/json
     Cache-Control: no-store
     Pragma: no-cache

     {
      "client_id": "dc-xliXMnoy6LN7Rh2Zu0fZan",
      "client_name": "Amazon Inc: Amazon Prime Movies Oct 23 2017"
      "logo_uri": "https://prime.amazon.com/logo.png"
      "redirect_uris":
      [
        "https://prime.amazon.com/cb",
        "https://prime.amazon.co.uk/cb"
      ],
      "id_token_signed_response_alg": "ES256",
      "request_object_signing_alg": "ES256",
      "grant_types": ["authorization_code", "refresh_token"],
      "software_id": "65d1f27c-4aea-4549-9c21-60e495a7a86f",
      "software_logo_uri": "https://prime.amazon.com/logo.png"
      "software_client_name": "Amazon Prime Movies",
      "software_client_name#ja-Jpan-JP":
         "\u30AF\u30E9\u30A4\u30A2\u30F3\u30C8\u540D",
      "software_roles": [
             "PISP",
             "AISP"
      ],
      "scope": "openid makepayment",
      "token_endpoint_auth_method": "private_key_jwt",
      "software_jwks_endpoint": "https://jwks.openbanking.org.uk/org_id/software_id.jkws"
     }

Unsuccessful Client Registration Response

In the case where the ASPSP makes a negative determination and refuses to create a client, the ASPSP MUST return a client registration error response to the TPP conforming to Section 3.2.2 of [RFC7591].

EXAMPLE CLIENT REGISTRATION ERROR RESPONSE

HTTP/1.1 400 Bad Request
     Content-Type: application/json
     Cache-Control: no-store
     Pragma: no-cache

     {
      "error": "unapproved_software_statement",
      "error_description": "Some actionable reason why an ASPSP might reject a valid SSA"
     }  

Manual Client Registration

An ASPSP MAY choose to offer a developer web portal for the purposes of client registration. If an OpenBanking-related web portal is offered, the ASPSP portal MUST act as a [SAML2] or [OIDC] compliant relying party to the OpenBanking Directory, where the PTC will be strongly authenticated.

Single Sign-on Configuration

The OpenBanking Directory Single Sign-on service MUST

• Act as a [FAPI] compliant OpenID Connect Identity Provider in the Identity Provider role for valid ASPSPs.
• Act as a [SAML2] Identity Provider compliant to OB supported profiles

OIDC Available Claims

References

Normative References

[FAPI] "Financial API - Part 1: Read Only API Security Profile" http://openid.net/specs/openid-financial-api-part-1.html

...

[SAML2] "Assertions and Protocols for the OASIS Security Assertion Markup Language (SAML) 2.0" https://docs.oasis-open.org/security/saml/v2.0/saml-core-2.0-os.pdf

Informative References

[PSD2] "Payment Services Directive 2" https://publications.europa.eu/en/publication-detail/-/publication/dd85ef2e-a953-11e5-b528-01aa75ed71a1