> ## Documentation Index > Fetch the complete documentation index at: https://developers.authlete.com/llms.txt > Use this file to discover all available pages before exploring further. # How to use FAPI feature > Technical guide on utilizing the Financial-grade API (FAPI) feature in Authlete detailing the necessary configurations and steps for enabling FAPI at runtime. For **Authlete 2.x** documentation, see [2.x version](/v2/protocols-and-flows/compliance-profiles/how-to-use-fapi). ## Overview This document explains how to use **Financial-grade API (FAPI)** feature in Authlete. > FAPI feature is available since Authlete 2.0. If you are using Authlete 2.2+, refer to [Financial-grade API (FAPI) Basics](/protocols-and-flows/compliance-profiles/fapi-basics). ## Introduction ### FAPI Support in Authlete Authlete supports both major versions of the Financial-grade API (FAPI): **FAPI 1.0** and **FAPI 2.0**. FAPI 1.0 defines two security profiles: * **Read-only API profile** (specified in Part 1) * **Read-and-write API profile** (specified in Part 2) Each profile has distinct requirements for authorization servers, meaning the behavior of the authorization server will depend on the specific profile in use. To enable FAPI functionality in Authlete, you must configure your service and client to meet the requirements of the desired profile. Authlete supports two modes for applying FAPI conformance checks: 1. **Static Mode**: All incoming requests are evaluated for compliance with the configured FAPI level. While strict, this mode may not be suitable in environments where the authorization server needs to support multiple clients with varying conformance levels. 2. **Dynamic (Runtime) Mode**: FAPI conformance checks are applied dynamically based on the OAuth scope provided in each request. This mode is more flexible and allows the authorization server to serve clients with different compliance requirements. This article focuses on enabling FAPI compliance dynamically at runtime. In this mode, the request parameters sent by the client to the authorization server must be configured properly. **Important:** Authlete determines whether the FAPI feature is enabled for a request based on these runtime parameters. Even if your service and client configurations satisfy the FAPI requirements, the feature will not be activated if the request parameters are misconfigured. The following steps outline how Authlete determines whether to enable FAPI at runtime: 1. Extract the scopes included in the request or associated with the request. 2. Check the attributes of each scope (see Appendix 1) and apply the following logic: | Condition | Authlete Behavior | | -------------------------------------------------------------------------------- | -------------------------------------------------- | | If the scope has a FAPI read-only attribute (`key = fapi` and `value = r`) | Authlete enforces the read-only API profile. | | If the scope has a FAPI read-and-write attribute (`key = fapi` and `value = rw`) | Authlete enforces the read-and-write API profile. | | Otherwise | Authlete defaults to regular OAuth 2.0/OIDC flows. | In the following sections, we will see more details of how to configure a service, a client and request parameters for both profiles. ## Service configurations This section explains how to configure a service to support FAPI profiles. 1. Log in to the [Management Console](https://console.authlete.com). 2. Click **Create New Service**. 3. On the **Service Setup** screen: * Enter a **Service Name** and **Description**. * Select `FAPI` in **FAPI Service Profile**. ![Screen\_Shot\_2021-07-26\_at\_20](https://storage.googleapis.com/authlete-website/resources/kb/how-to-use-fapi/1.png) ### Configurations for read-only API profile Configure a service as below. | Property | Configuration | | --------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Supported Service Profiles | Choose **FAPI**. | | Supported Client Authentication Methods | Choose at least one of the followings: TLS\_CLIENT\_AUTH, SELF\_SIGNED\_TLS\_CLIENT\_AUTH, CLIENT\_SECRET\_JWT, PRIVATE\_KEY\_JWT. Note: If all the FAPI clients communicating with this service are public clients, this configuration is not mandatory. | | Supported Scopes | Create at least a scope that has an "read-only" attribute. | ### Configurations for read-and-write API profile To support read-and-write API profile, you need to configure a service according to the configurations for read-only API profile and the following additional configurations. (Some configurations for read-only API profile are overridden.) | Property | Configuration | | ------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | Supported Authentication Context Class References | Set an appropriate value.(e.g. urn:mace:incommon:iap:silver) | | Supported Response Types | Choose at least one of the followings: CODE\_ID\_TOKEN, CODE\_ID\_TOKEN\_TOKEN. Note: If all the FAPI clients communicating with this service use JARM (See Appendix 2), this configuration is not mandatory. | | Supported Client Authentication Methods | Choose at least one of the followings: TLS\_CLIENT\_AUTH, SELF\_SIGNED\_TLS\_CLIENT\_AUTH, PRIVATE\_KEY\_JWT. Note: If all the FAPI clients communicating with this service are public clients, this configuration is not mandatory. | | TLS Client Certificate Bound Access Tokens | Choose **Supported**. | | Supported Scopes | Create at least a scope that has an "read-and-write" attribute. | ## Client configurations This section explains how to configure a client to support FAPI profiles. ### Configurations for read-only API profile Configure a client as below. | Property | Configuration | | ---------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Client Authentication Method | If this client is a confidential client, choose one of the followings: TLS\_CLIENT\_AUTH, SELF\_SIGNED\_TLS\_CLIENT\_AUTH, CLIENT\_SECRET\_JWT, PRIVATE\_KEY\_JWT. | | Redirect Uris | Set a URI starting with https. | | JWK Set Content | Note: this configuration is not mandatory if "JWK Set URI" is used. If this client uses PRIVATE\_KEY\_JWT as its client authentication method, the value of this property must contain a public key for verifying assertion signature and the key must satisfy the requirements in Appendix 3. | | JWK Set URI | Note: this configuration is not mandatory if "JWK Set Content" is used. If this client uses PRIVATE\_KEY\_JWT as its client authentication method, the value of the JWK set pointed by this property must contain a public key for verifying assertion signature and the key must satisfy the requirements in Appendix 3. | ### Configurations for read-and-write API profile To support read-and-write API profile, you need to configure a client according to the configurations for read-only API profile and the following additional configurations. (Some configurations for read-only API profile are overridden.) | Property | Configuration | | ------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Response Type | Choose at least one of the followings: CODE\_ID\_TOKEN, CODE\_ID\_TOKEN\_TOKEN. Note: If this client uses JARM (See Appendix 2), this configuration is not mandatory. | | Supported Client Authentication Methods | If this client is a confidential client, choose one of the followings: TLS\_CLIENT\_AUTH, SELF\_SIGNED\_TLS\_CLIENT\_AUTH, PRIVATE\_KEY\_JWT. | | TLS Client Certificate Bound Access Tokens | Choose **Enabled**. | | Authorization Response Signature Algorithm | If this client uses JARM, choose one of the followings: PS256, ES256. | | Assertion Signature Algorithm | If this client uses PRIVATE\_KEY\_JWT as its client authentication method, choose one of the followings: PS256, ES256. | | Request Object Signature Algorithm | Choose one of the followings: PS256, ES256. | | ID Token Signature Algorithm | If this client asks the authorization server for ID tokens, choose one of the followings: PS256, ES256. | | User Info Signature Algorithm | If this client uses user info endpoint, choose one of the followings: PS256, ES256. | ## Request This section explains how to configure request parameters (for authorization endpoint and token endpoint) to support FAPI profiles. ## Authorization request ### Authorization request for read-only API profile **Requirements for request parameters** | Parameter | Requirement | | ----------------------- | --------------------------------------------------------------------------------------------------------------------------------------- | | redirect\_uri | Set a URI that satisfies the following requirements: must exactly match one of the pre-registered redirect URIs; must start with https. | | state | Required if 'openid' scope is not contained in the 'scope' request parameters. | | code\_challenge | Set a value that complies with PKCE ([RFC 7636](https://tools.ietf.org/html/rfc7636)). | | code\_challenge\_method | Must be 'S256'. | | scope | Must include at least a scope that has an "read-only" attribute. | **Example** ```text theme={null} # # An example request from a public client. # # Note: # * scope: 'account' scope has a "read-only" attribute. # * state: Optional but recommended (OAuth 2.0). # * nonce: Required if the 'response_type' request parameter contains # 'id_token' (OpenID Connect). # GET /api/authorization? response_type=code+id_token& client_id=285946231596& redirect_uri=https://my-client.com/callback& scope=openid+accounts& code_challenge=E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM& code_challenge_method=S256& state=mystate& nonce=mynonce ``` ### Authorization request for read-and-write API profile **Requirements for request parameters** To support read-and-write API profile, you need to configure request parameters according to the requirements for read-only API profile and the following additional requirements. (Some requirements for read-only API profile are overridden.) | Parameter | Requirements | | ----------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------- | | request | Note: If 'request\_uri' parameter is used, this requirement is not mandatory. Set a request object that satisfy the requirements in Appendix 4. | | request\_uri | Note: If 'request' parameter is used, this requirement is not mandatory. Set a URL pointing a request object that satisfy the requirements in Appendix 4. | | response\_type | Set 'code id\_token' or 'code id\_token token'. Note: If this client always uses JARM, this requirement is not mandatory. | | code\_challenge | Set a value that complies with PKCE ([RFC 7636](https://tools.ietf.org/html/rfc7636)) if this client is a public client. | | code\_challenge\_method | Must be 'S256' if this client is a public client. | | scope | Must include at least a scope that has an "read-and-write" attribute. | | claims | Must include the 'acr' claim as an essential claim ("essential":true). See example below. | Example claims structure: ```json theme={null} { "id_token": { "acr": { "essential": true, "values": ["urn:mace:incommon:iap:silver"] } } } ``` **Example** ```text theme={null} # # An example request from a confidential client. # # Note: # * scope: 'account' scope has a "read-and-write" attribute. # * state: Optional but recommended (OAuth 2.0). # * nonce: Required if the 'response_type' request parameter contains # 'id_token' (OpenID Connect). # GET /api/authorization? response_type=code+id_token& client_id=291985138172& scope=openid+payments& redirect_uri=https://my-client.com/callback& state=mystate& nonce=mynonce& claims={"id_token":{"acr":{"essential":true,"values":["urn:mace:incommon:iap:silver"]}}}& request=eyJh...[省略]...nPQ ``` ## Token request ### Token request for read-only API profile **Requirements for request parameters** | Parameter | Requirement | | ----------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | client\_assertion | If this client uses PRIVATE\_KEY\_JWT as its client authentication method, the value of this property must contain a public key for verifying assertion signature and the key must satisfy the requirements in Appendix 3. | **Example** ```text theme={null} # # An example request from a public client. # POST /api/token client_id=285946231596& grant_type=authorization_code& code=_vaXlQ_ItUX4hiWzXgOT-Jp9-oVPKGQ6Q6QZu_P2GXw& redirect_uri=https://my-client.com/callback& code_verifier=dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk ``` ### Token request for read-and-write API profile **Requirements for request parameters** To support read-and-write API profile, you need to configure request parameters according to the requirements for read-only API profile and the following additional requirements. (Some requirements for read-only API profile are overridden.) | Parameter | Requirement | | ----------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | client\_assertion | If this client uses PRIVATE\_KEY\_JWT as its client authentication method, the value of this property must be signed with the algorithm specified as 'Assertion Signature Algorithm'. | **Client certificate** The client needs to present a client certificate to the token endpoint as 'TLS Client Certificate Bound Access Tokens' is enabled for the client. **Example** ```text theme={null} # # An example request from a confidential client. # # Note: # * The client uses PRIVATE_KEY_JWT as its client authentication method. # * The client needs to present a client certificate to the token endpoint, # as 'TLS Client Certificate Bound Access Tokens' is enabled for the client. # POST /api/token client_id=291985138172& grant_type=authorization_code& code=YG-gD9v-vmnuKaHkRHcvWq1UxlxT_9vgj28ffxIAX40& redirect_uri=https://my-client.com/callback& client_assertion=eyJh...[omitted]...OWg& client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer ``` ## Appendix ### 1. Scope attributes See [this article](/configuration-reference/tokens-and-claims/scope-attributes). ### 2. JARM See [this article](/configuration-reference/endpoints/enabling-jarm). ### 3. Requirements for key size FAPI Part1 says > Financial Services – Financial API - Part 1, 5.2.2. Authorization Server > > The authorization server,\ >   ...\ >   5. shall require a key of size 2048 bits or larger if RSA\ >     algorithms are used for the client authentication;\ >   6. shall require a key of size 160 bits or larger if elliptic\ >     curve algorithms are used for the client authentication; Then, a public key for signing a client assertion (JWS) and a private key for verifying the signature must satisfy the following requirements. | Client assertion algorithm type | Requirements for key size | | ------------------------------- | ------------------------------------------------------- | | RSA algorithm | The key size must be equal to or larger than 2048 bits. | | EC algorithm | The key size must be equal to or larger than 160 bits. | | Otherwise | No requirements. | ### 4. Requirements for request objects FAPI Part2 says > Financial Services – Financial API - Part 2, 5.2.2. Authorization Server > > The authorization server,\ >   ...\ >   1. shall require the request or request\_uri parameter to be passed as a JWS signed JWT as in clause 6 of \[OIDC];\ >   ...\ >   10. shall require that all parameters are present inside the signed request object passed in the request or request\_uri parameter;\ >   ...\ >   13. shall require the request object to contain an exp claim;\ >   ...\ >   15. shall require the aud claim in the request object to be, or to be an array containing, the OP's Issuer Identifier URL; Additionally, the following requirements for JWS signature must be satisfied. > Financial Services – Financial API - Part 2, 8.6 JWS algorithm considerations > > Both clients and authorization servers:\ >     1. shall use PS256 or ES256 algorithms;\ >     2. should not use algorithms that use RSASSA-PKCS1-v1\_5 (e.g. RS256);\ >     3. shall not use none; In summary, in order to support read-and-write API profile, request objects: * Must be signed with the algorithm specified as 'Request Object Signature Algorithm'. * Must include all the request parameters. * Must include the 'exp' claim * Must include the 'aud' claim and the value must be the value of 'Token Issuer Identifier'. The following example shows the payload of a request object that satisfies the requirements. ```json theme={null} { "response_type": "code id_token", "exp": 1554973000, "aud": "https://my-authz-server.com/", "client_id": "291985138172", "scope": "openid payments", "redirect_uri": "https://my-client.com/callback", "state": "mystate", "nonce": "mynonce", "claims": { "id_token": { "acr": { "values": ["urn:mace:incommon:iap:silver"], "essential": true } } } } ```