[id="con-advanced-settings_{context}"]
= Advanced configuration
[role="_abstract"]

After completing the fields on the *Settings* tab, you can use the other tabs to perform advanced configuration.  For example, you can use the *Permissions* and *Roles* tabs to configure fine-grained authentication for administrators. See <<_fine_grain_permissions, Fine grain admin permissions>>.  Also, see the remaining sections in this chapter for other capabilities.

== Advanced tab

When you click the *Advanced* tab, additional fields are displayed.  For details on a specific field, click the question mark icon for that field.  However, certain fields are described in detail in this section.

== Fine grain OpenID Connect configuration

*Logo URL*

URL that references a logo for the Client application.

*Policy URL*

URL that the Relying Party Client provides to the End-User to read about how the profile data will be used.

*Terms of Service URL*

URL that the Relying Party Client provides to the End-User to read about the Relying Party's terms of service.

[[_jwe-id-token-encryption]]
*Signed and Encrypted ID Token Support*

{project_name} can encrypt ID tokens according to the https://datatracker.ietf.org/doc/html/rfc7516[Json Web Encryption (JWE)] specification. The administrator determines if ID tokens are encrypted for each client.

The key used for encrypting the ID token is the Content Encryption Key (CEK). {project_name} and a client must negotiate which CEK is used and how it is delivered. The method used to determine the CEK is the Key Management Mode. The Key Management Mode that {project_name} supports is Key Encryption.

In Key Encryption:

. The client generates an asymmetric cryptographic key pair.
. The public key is used to encrypt the CEK.
. {project_name} generates a CEK per ID token
. {project_name} encrypts the ID token using this generated CEK
. {project_name} encrypts the CEK using the client's public key.
. The client decrypts this encrypted CEK using their private key
. The client decrypts the ID token using the decrypted CEK.

No party, other than the client, can decrypt the ID token.

The client must pass its public key for encrypting CEK to {project_name}. {project_name} supports downloading public keys from a URL provided by the client. The client must provide public keys according to the https://datatracker.ietf.org/doc/html/rfc7517[Json Web Keys (JWK)] specification.

The procedure is:

. Open the client's *Keys* tab.
. Toggle *JWKS URL* to ON.
. Input the client's public key URL in the *JWKS URL* textbox.

Key Encryption's algorithms are defined in the https://datatracker.ietf.org/doc/html/rfc7518#section-4.1[Json Web Algorithm (JWA)] specification. {project_name} supports:

* RSAES-PKCS1-v1_5(RSA1_5)
* RSAES OAEP using default parameters (RSA-OAEP)
* RSAES OAEP 256 using SHA-256 and MFG1 (RSA-OAEP-256)

The procedure to select the algorithm is:

. Open the client's *Advanced* tab.
. Open *Fine Grain OpenID Connect Configuration*.
. Select the algorithm from *ID Token Encryption Content Encryption Algorithm* pulldown menu.

== Open ID Connect Compatibility Modes

This section exists for backward compatibility.  Click the question mark icons for details on each field.

[[_mtls-client-certificate-bound-tokens]]
*OAuth 2.0 Mutual TLS Certificate Bound Access Tokens Enabled*

Mutual TLS binds an access token and a refresh token together with a client certificate, which is exchanged during a TLS handshake. This binding prevents an attacker from using stolen tokens.

This type of token is a holder-of-key token. Unlike bearer tokens, the recipient of a holder-of-key token can verify if the sender of the token is legitimate.

If this setting is on, the workflow is:

. A token request is sent to the token endpoint in an authorization code flow or hybrid flow.
. {project_name} requests a client certificate.
. {project_name} receives the client certificate.
. {project_name} successfully verifies the client certificate.

If verification fails, {project_name} rejects the token.

In the following cases, {project_name} will verify the client sending the access token or the refresh token:

* A token refresh request is sent to the token endpoint with a holder-of-key refresh token.
* A UserInfo request is sent to UserInfo endpoint with a holder-of-key access token.
* A logout request is sent to Logout endpoint with a holder-of-key refresh token.

See https://datatracker.ietf.org/doc/html/draft-ietf-oauth-mtls-08#section-3[Mutual TLS Client Certificate Bound Access Tokens] in the OAuth 2.0 Mutual TLS Client Authentication and Certificate Bound Access Tokens for more details.

[NOTE]
====
Currently, {project_name} client adapters do not support holder-of-key token verification. {project_name} adapters treat access and refresh tokens as bearer tokens.
====

[[_proof-key-for-code-exchange]]
*Proof Key for Code Exchange Code Challenge Method*

If an attacker steals an authorization code of a legitimate client, Proof Key for Code Exchange (PKCE) prevents the attacker from receiving the tokens that apply to the code.

An administrator can select one of these options:

*(blank)*:: {project_name} does not apply PKCE unless the client sends appropriate PKCE parameters to {project_name}s authorization endpoint.
*S256*:: {project_name} applies to the client PKCE whose code challenge method is S256.
*plain*:: {project_name} applies to the client PKCE whose code challenge method is plain.

See https://datatracker.ietf.org/doc/html/rfc7636[RFC 7636 Proof Key for Code Exchange by OAuth Public Clients] for more details.

[[_mapping-acr-to-loa-client]]
*ACR to Level of Authentication (LoA) Mapping*

In the advanced settings of a client, you can define which `Authentication Context Class Reference (ACR)` value is mapped to which `Level of Authentication (LoA)`.
This mapping can be specified also at the realm as mentioned in the <<_mapping-acr-to-loa-realm,ACR to LoA Mapping>>. A best practice is to configure this mapping at the
realm level, which allows to share the same settings across multiple clients.

The `Default ACR Values` can be used to specify the default values when the login request is sent from this client to {project_name} without `acr_values` parameter and without
a `claims` parameter that has an `acr` claim attached. See https://openid.net/specs/openid-connect-registration-1_0.html#ClientMetadata[official OIDC dynamic client registration specification].

WARNING: Note that default ACR values are used as the default level, however it cannot be reliably used to enforce login with the particular level.
For example, assume that you configure the `Default ACR Values` to level 2. Then by default, users will be required to authenticate with level 2.
However when the user explicitly attaches the parameter into login request such as `acr_values=1`, then the level 1 will be used. As a result, if the client
really requires level 2, the client is encouraged to check the presence of the `acr` claim inside ID Token and double-check that it contains the requested level 2.

image:images/client-oidc-map-acr-to-loa.png[alt="ACR to LoA mapping"]

For further details see  <<_step-up-flow,Step-up Authentication>> and  https://openid.net/specs/openid-connect-core-1_0.html#acrSemantics[the official OIDC specification].
