﻿---
title: JWT authentication
description: Elasticsearch can be configured to trust JSON Web Tokens (JWTs) issued from an external service as bearer tokens for authentication. When a JWT realm...
url: https://www.elastic.co/elastic/docs-builder/docs/2988/deploy-manage/users-roles/cluster-or-deployment-auth/jwt
products:
  - Elastic Cloud Enterprise
  - Elastic Cloud Hosted
  - Elasticsearch
applies_to:
  - Elastic Stack: Generally available
---

# JWT authentication
Elasticsearch can be configured to trust JSON Web Tokens (JWTs) issued from an external service as bearer tokens for authentication.
When a JWT realm is used to authenticate with Elasticsearch, a distinction is made between the client that is connecting to Elasticsearch, and the user on whose behalf the request should run. The JWT authenticates the user, and a separate credential authenticates the client.
The JWT realm supports two token types, `id_token` (the default) and `access_token`:
1. `id_token`: An application authenticates and identifies a user with an authentication flow, e.g. OpenID Connect (OIDC), and then accesses Elasticsearch on behalf of the authenticated user using a JSON Web Token (JWT) conforming to OIDC ID Token specification. This option is available in deployments using Elastic Stack 8.2+.
2. `access_token`: An application accesses Elasticsearch using its own identity, encoded as a JWT, e.g. The application authenticates itself to a central identity platform using an OAuth2 Client Credentials Flow and then uses the resulting JWT-based access token to connect to Elasticsearch. This option is available in deployments using Elastic Stack 8.7+.

<note>
  A single JWT realm can only work with a single token type. To handle both token types, you must configure at least two JWT realms. You should choose the token type carefully based on the use case because it impacts on how validations are performed.
</note>

The JWT realm validates the incoming JWT based on its configured token type. JSON Web Tokens (JWT) of both types must contain the following 5 pieces of information. While ID Tokens, based on the OIDC specification, have strict rules for what claims should provide these information, access tokens allow some claims to be configurable.
**Claims**

| Information     | ID Token | Access Token                                                                  |
|-----------------|----------|-------------------------------------------------------------------------------|
| Issuer          | `iss`    | `iss`                                                                         |
| Subject         | `sub`    | Defaults to `sub`, but can fall back to another claim if `sub` does not exist |
| Audiences       | `aud`    | Defaults to `aud`, but can fall back to another claim if `aud` does not exist |
| Issue Time      | `iat`    | `iat`                                                                         |
| Expiration Time | `exp`    | `exp`                                                                         |

In addition, Elasticsearch also validates `nbf` and `auth_time` claims for ID Tokens if these claims are present. But these claims are ignored for access tokens.
Overall, the access token type has more relaxed validation rules and is suitable for more generic JWTs, including self-signed ones.

## ID Tokens from OIDC workflows

JWT authentication in Elasticsearch is derived from OIDC user workflows, where different tokens can be issued by an OIDC Provider (OP), including ID Tokens. ID Tokens from an OIDC provider are well-defined JSON Web Tokens (JWT) and should be always compatible with a JWT realm of the `id_token` token type. The subject claim of an ID token represents the end-user. This means that ID tokens will generally have many allowed subjects. Therefore, a JWT realm of `id_token` token type does *not* mandate the `allowed_subjects` (or `allowed_subject_patterns`) validation.
<note>
  Because JWTs are obtained external to Elasticsearch, you can define a custom workflow instead of using the OIDC workflow. However, the JWT format must still be JSON Web Signature (JWS). The JWS header and JWS signature are validated using OIDC ID token validation rules.
</note>

Elasticsearch supports a separate [OpenID Connect realm](https://www.elastic.co/elastic/docs-builder/docs/2988/deploy-manage/users-roles/cluster-or-deployment-auth/openid-connect). It is preferred for any use case where Elasticsearch can act as an OIDC RP. The OIDC realm is the only supported way to enable OIDC authentication in Kibana.
<tip>
  Users authenticating with a JWT realm can optionally impersonate another user with the [`run_as`](https://www.elastic.co/elastic/docs-builder/docs/2988/deploy-manage/users-roles/cluster-or-deployment-auth/submitting-requests-on-behalf-of-other-users) feature. See [Applying the `run_as` privilege to JWT realm users](#jwt-realm-runas).
</tip>


## Access tokens

A common method to obtain access tokens is with the OAuth2 client credentials flow. A typical usage of this flow is for an application to get a credential for itself. This is the use case that the `access_token` token type is designed for. It is likely that this application also obtains ID Tokens for its end-users. To prevent end-user ID Tokens being used to authenticate with the JWT realm configured for the application, we mandate `allowed_subjects` or `allowed_subject_patterns` validation when a JWT realm has token type `access_token`.
<note>
  Not every access token is formatted as a JSON Web Token (JWT). For it to be compatible with the JWT realm, it must at least use the JWT format and satisfies relevant requirements in the above table.
</note>


## Configure Elasticsearch to use a JWT realm

To use JWT authentication, create the realm in the [`elasticsearch.yml`](https://www.elastic.co/elastic/docs-builder/docs/2988/deploy-manage/stack-settings) file to configure it within the Elasticsearch authentication chain.
The JWT realm has a few mandatory settings, plus optional settings that are described in [JWT realm settings](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2988/reference/elasticsearch/configuration-reference/security-settings#ref-jwt-settings).
<note>
  Client authentication is enabled by default for the JWT realms. Disabling client authentication is possible, but strongly discouraged.
</note>

1. Configure the realm using your preferred token type:

<tab-set>
  <tab-item title="ID tokens">
    The following example includes the most common settings, which are not intended for every use case:
    ```yaml
    xpack.security.authc.realms.jwt.jwt1:
      order: 3
      token_type: id_token
      client_authentication.type: shared_secret
      allowed_issuer: "<example-issuer-url>/jwt/"
      allowed_audiences: [ "8fb85eba-979c-496c-8ae2-a57fde3f12d0" ]
      allowed_signature_algorithms: [RS256,HS256]
      pkc_jwkset_path: jwt/jwkset.json
      claims.principal: sub
    ```

    <definitions>
      <definition term="order">
        Specifies a realm `order` of `3`, which indicates the order in which the configured realm is checked when authenticating a user. Realms are consulted in ascending order, where the realm with the lowest order value is consulted first.
      </definition>
      <definition term="token_type">
        Instructs the realm to treat and validate incoming JWTs as ID Tokens (`id_token`).
      </definition>
      <definition term="client_authentication.type">
        Specifies the client authentication type as `shared_secret`, which means that the client is authenticated using an HTTP request header that must match a pre-configured secret value. The client must provide this shared secret with every request in the `ES-Client-Authentication` header and using the `SharedSecret` scheme. The header value must be a case-sensitive match to the realm’s `client_authentication.shared_secret`.
      </definition>
      <definition term="allowed_issuer">
        Sets a verifiable identifier for your JWT issuer. This value is typically a URL, UUID, or some other case-sensitive string value.
      </definition>
      <definition term="allowed_audiences">
        Specifies a list of JWT audiences that the realm will allow. These values are typically URLs, UUIDs, or other case-sensitive string values.
      </definition>
      <definition term="allowed_signature_algorithms">
        Indicates that Elasticsearch should use the `RS256` or `HS256` signature algorithms to verify the signature of the JWT from the JWT issuer.
      </definition>
      <definition term="pkc_jwkset_path">
        The file name or URL to a JSON Web Key Set (JWKS) with the public key material that the JWT Realm uses for verifying token signatures. A value is considered a file name if it does not begin with `https`. The file name is resolved relative to the Elasticsearch configuration directory. If a URL is provided, then it must begin with `https://` (`http://` is not supported). Elasticsearch automatically caches the JWK set and will attempt to refresh the JWK set upon signature verification failure, as this might indicate that the JWT Provider has rotated the signing keys. Background JWKS reloading can also be configured with the setting `pkc_jwkset_reload.enabled`. This ensures that rotated keys are automatically discovered and used to verify JWT signatures.
      </definition>
      <definition term="pkc_jwkset_reload.enabled Elastic Stack: Generally available since 9.3">
        Indicates whether JWKS background reloading is enabled. Defaults to `false`.
      </definition>
      <definition term="pkc_jwkset_reload.file_interval Elastic Stack: Generally available since 9.3">
        Specifies the reload interval for file-based JWKS. Defaults to `5m`.
      </definition>
      <definition term="pkc_jwkset_reload.url_interval_min Elastic Stack: Generally available since 9.3">
        Specifies the minimum reload interval for URL-based JWKS. The `Expires` and `Cache-Control` HTTP response headers inform the reload interval. This configuration setting is the lower bound of what is considered, and it is also the default interval in the absence of useful response headers. Defaults to `1h`.
      </definition>
      <definition term="pkc_jwkset_reload.url_interval_max Elastic Stack: Generally available since 9.3">
        Specifies the maximum reload interval for URL-based JWKS. This configuration setting is the upper bound of what is considered from header responses (`5d`).
      </definition>
      <definition term="claims.principal">
        The name of the JWT claim that contains the user’s principal. Defaults to `username`.
      </definition>
    </definitions>
  </tab-item>

  <tab-item title="Access tokens">
    The following is an example snippet for configuring a JWT realm for handling access tokens:
    ```yaml
    xpack.security.authc.realms.jwt.jwt2:
      order: 4
      token_type: access_token
      client_authentication.type: shared_secret
      allowed_issuer: "<example-issuer-url>/jwt/"
      allowed_subjects: [ "123456-compute@admin.example.com" ]
      allowed_subject_patterns: [ "wild*@developer?.example.com", "/[a-z]+<1-10>\\@dev\\.example\\.com/"]
      allowed_audiences: [ "elasticsearch" ]
      required_claims:
        token_use: access
        version: ["1.0", "2.0"]
      allowed_signature_algorithms: [RS256,HS256]
      pkc_jwkset_path: "<example-idp-url>/.well-known/configuration"
      fallback_claims.sub: client_id
      fallback_claims.aud: scope
      claims.principal: sub
    ```

    <definitions>
      <definition term="token_type">
        Instructs the realm to treat and validate incoming JWTs as access tokens (`access_token`).
      </definition>
      <definition term="allowed_subjects">
        Specifies a list of JWT subjects that the realm will allow. These values are typically URLs, UUIDs, or other case-sensitive string values.
      </definition>
      <definition term="allowed_subject_patterns">
        Analogous to `allowed_subjects` but it accepts a list of [Lucene regexp](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2988/reference/query-languages/query-dsl/regexp-syntax) and wildcards for the allowed JWT subjects. Wildcards use the `*` and `?` special characters (which are escaped by `\`) to mean "any string" and "any single character" respectively, for example "a?**", matches "a1*" and "ab*whatever", but not "a", "abc", or "abc*" (in Java strings `\` must itself be escaped by another `\`). [Lucene regexp](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2988/reference/query-languages/query-dsl/regexp-syntax) must be enclosed between `/`, for example "/https?://[^/]+/?/" matches any http or https URL with no path component (matches "[https://elastic.co/](https://elastic.co/)" but not "[https://elastic.co/guide](https://elastic.co/guide)").
      </definition>
    </definitions>
    At least one of the `allowed_subjects` or `allowed_subject_patterns` settings must be specified (and be non-empty) when `token_type` is `access_token`.When both `allowed_subjects` and `allowed_subject_patterns` settings are specified an incoming JWT’s `sub` claim is accepted if it matches any of the two lists.
    <definitions>
      <definition term="required_claims">
        Specifies a list of key/value pairs for additional verifications to be performed against a JWT. The values are either a string or an array of strings.
      </definition>
      <definition term="fallback_claims.sub">
        The name of the JWT claim to extract the subject information if the `sub` claim does not exist. This setting is only available when `token_type` is `access_token`. The fallback is applied everywhere the `sub` claim is used. In the above snippet, it means the `claims.principal` will also fallback to `client_id` if `sub` does not exist.
      </definition>
      <definition term="fallback_claims.aud">
        The name of the JWT claim to extract the audiences information if the `aud` claim does not exist. This setting is only available when `token_type` is `access_token`. The fallback is applied everywhere the `aud` claim is used.
      </definition>
    </definitions>
  </tab-item>
</tab-set>

1. Add secure settings [to the Elasticsearch keystore](https://www.elastic.co/elastic/docs-builder/docs/2988/deploy-manage/security/secure-settings):
   - The `shared_secret` value for `client_authentication.type`
  (`xpack.security.authc.realms.jwt.jwt1.client_authentication.shared_secret`)
- The HMAC keys for `allowed_signature_algorithms`
  (`xpack.security.authc.realms.jwt.jwt1.hmac_jwkset`)
  This setting can be a path to a JWKS, which is a resource for a set of JSON-encoded secret keys. The file can be removed after you load the contents into the Elasticsearch keystore.

<note>
  Using the JWKS is preferred. However, you can add an HMAC key in string format using `xpack.security.authc.realms.jwt.jwt1.hmac_key`. This format is compatible with HMAC UTF-8 keys, but only supports a single key with no attributes. You can only use one HMAC format (either `hmac_jwkset` or `hmac_key`) at a time.
</note>


## JWT encoding and validation

JWTs can be parsed into three pieces:
<definitions>
  <definition term="Header">
    Provides information about how to validate the token.
  </definition>
  <definition term="Claims">
    Contains data about the calling user or application.
  </definition>
  <definition term="Signature">
    The data that’s used to validate the token.
  </definition>
</definitions>

```js
Header: {"typ":"JWT","alg":"HS256"}
Claims: {"aud":"aud8","sub":"security_test_user","iss":"iss8","exp":4070908800,"iat":946684800}
Signature: UnnFmsoFKfNmKMsVoDQmKI_3-j95PCaKdgqqau3jPMY
```

This example illustrates a partial decoding of a JWT. The validity period is from 2000 to 2099 (inclusive), as defined by the issue time (`iat`) and expiration time (`exp`). JWTs typically have a validity period shorter than 100 years, such as 1-2 hours or 1-7 days, not an entire human life.
The signature in this example is deterministic because the header, claims, and HMAC key are fixed. JWTs typically have a `nonce` claim to make the signature non-deterministic. The supported JWT encoding is JSON Web Signature (JWS), and the JWS `Header` and `Signature` are validated using OpenID Connect ID Token validation rules. Some validation is customizable through [JWT realm settings](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2988/reference/elasticsearch/configuration-reference/security-settings#ref-jwt-settings).

### Header claims

The header claims indicate the token type and the algorithm used to sign the token.
<definitions>
  <definition term="alg">
    (Required, String) Indicates the algorithm that was used to sign the token, such as `HS256`. The algorithm must be in the realm’s allow list.
  </definition>
  <definition term="typ">
    (Optional, String) Indicates the token type, which must be `JWT`.
  </definition>
</definitions>


### Payload claims

Tokens contain several claims, which provide information about the user who is issuing the token, and the token itself. Depending on the token type, these information can optionally be identified by different claims.

#### JWT payload claims

The following claims are validated by a subset of OIDC ID token rules.
Elasticsearch doesn’t validate `nonce` claims, but a custom JWT issuer can add a random `nonce` claim to introduce entropy into the signature.
<note>
  You can relax validation of any of the time-based claims by setting `allowed_clock_skew`. This value sets the maximum allowed clock skew before validating JWTs with respect to their authentication time (`auth_time`), creation (`iat`), not before (`nbf`), and expiration times (`exp`).
</note>

<definitions>
  <definition term="iss">
    (Required, String) Denotes the issuer that created the ID token. The value must be an exact, case-sensitive match to the value in the `allowed_issuer` setting.
  </definition>
  <definition term="sub">
    (Required*, String) Indicates the subject that the ID token is created for. If the JWT realm is of the `id_token` type, this claim is mandatory. A JWT realm of the `id_token` type by defaults accepts all subjects. A JWT realm of the access_token type must specify the `allowed_subjects` setting and the subject value must be an exact, case-sensitive match to any of the CSV values in the allowed_subjects setting. A JWT realm of the access_token type can specify a fallback claim that will be used in place where the `sub` claim does not exist.
  </definition>
  <definition term="aud">
    (Required*, String) Indicates the audiences that the ID token is for, expressed as a comma-separated value (CSV). One of the values must be an exact, case-sensitive match to any of the CSV values in the `allowed_audiences` setting. If the JWT realm is of the `id_token` type, this claim is mandatory. A JWT realm of the `access_token` type can specify a fallback claim that will be used in place where the `aud` claim does not exist.
  </definition>
  <definition term="exp">
    (Required, integer) Expiration time for the ID token, expressed in UTC seconds since epoch.
  </definition>
  <definition term="iat">
    (Required, integer) Time that the ID token was issued, expressed in UTC seconds since epoch.
  </definition>
  <definition term="nbf">
    (Optional, integer) Indicates the time before which the JWT must not be accepted, expressed as UTC seconds since epoch. This claim is optional. If it exists, a JWT realm of `id_token` type will verify it, while a JWT realm of `access_token` will just ignore it.
  </definition>
  <definition term="auth_time">
    (Optional, integer) Time when the user authenticated to the JWT issuer, expressed as UTC seconds since epoch. This claim is optional. If it exists, a JWT realm of `id_token` type will verify it, while a JWT realm of `access_token` will just ignore it.
  </definition>
</definitions>


#### Elasticsearch settings for consuming JWT claims

Elasticsearch uses JWT claims for the following settings.
<definitions>
  <definition term="principal">
    (Required, String) Contains the user’s principal (username). The value is configurable using the realm setting `claims.principal`. You can configure an optional regular expression using the `claim_patterns.principal` to extract a substring.
  </definition>
  <definition term="groups">
    (Optional, JSON array) Contains the user’s group membership. The value is configurable using the realm setting `claims.groups`. You can configure an optional regular expression using the realm setting `claim_patterns.groups` to extract a substring value.
  </definition>
  <definition term="name">
    (Optional, String) Contains a human-readable identifier that identifies the subject of the token. The value is configurable using the realm setting `claims.name`. You can configure an optional regular expression using the realm setting `claim_patterns.name` to extract a substring value.
  </definition>
  <definition term="mail">
    (Optional, String) Contains the e-mail address to associate with the user. The value is configurable using the realm setting `claims.mail`. You can configure an optional regular expression using the realm setting `claim_patterns.mail` to extract a substring value.
  </definition>
  <definition term="dn">
    (Optional, String) Contains the user’s Distinguished Name (DN), which uniquely identifies a user or group. The value is configurable using the realm setting `claims.dn`. You can configure an optional regular expression using the realm setting `claim_patterns.dn` to extract a substring value.
  </definition>
</definitions>


## Role mapping

You can map JWT groups to roles in the following ways:
- Using the role mappings page in Kibana.
- Using the [role mapping API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-security-put-role-mapping).
- By delegating authorization [to another realm](#jwt-authorization-delegation).

For more information, see [Mapping users and groups to roles](https://www.elastic.co/elastic/docs-builder/docs/2988/deploy-manage/users-roles/cluster-or-deployment-auth/mapping-users-groups-to-roles).
<important>
  You can't map roles in the JWT realm using the `role_mapping.yml` file.
</important>


### Authorizing with the role mapping API

You can use the [create or update role mappings API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-security-put-role-mapping) to define role mappings that determine which roles should be assigned to each user based on their username, groups, or other metadata.
```json

{
  "roles" : [ "user" ], <2>
  "rules" : { "all" : [ <3>
      { "field": { "realm.name": "jwt1" } }, <4>
      { "field": { "username": "principalname1" } },
      { "field": { "dn": "CN=Principal Name 1,DC=example.com" } },
      { "field": { "groups": "group1" } },
      { "field": { "metadata.jwt_claim_other": "other1" } }
  ] },
  "enabled": true
}
```

If you use this API in the JWT realm, the following claims are available for role mapping:
<definitions>
  <definition term="principal">
    (Required, String) Principal claim that is used as the Elasticsearch user’s username.
  </definition>
  <definition term="dn">
    (Optional, String) Distinguished Name (DN) that is used as the Elasticsearch user’s DN.
  </definition>
  <definition term="groups">
    (Optional, String) Comma-separated value (CSV) list that is used as the Elasticsearch user’s list of groups.
  </definition>
  <definition term="metadata">
    (Optional, object) Additional metadata about the user, such as strings, integers, boolean values, and collections that are used as the Elasticsearch user’s metadata. These values are key value pairs formatted as `metadata.jwt_claim_<key>` = `<value>`.
  </definition>
</definitions>


### Delegating JWT authorization to another realm

If you [delegate authorization](/elastic/docs-builder/docs/2988/deploy-manage/users-roles/cluster-or-deployment-auth/realm-chains#authorization_realms) to other realms from the JWT realm, only the `principal` claim is available for role lookup. When delegating the assignment and lookup of roles to another realm from the JWT realm, claims for `dn`, `groups`, `mail`, `metadata`, and `name` are not used for the Elasticsearch user’s values. Only the JWT `principal` claim is passed to the delegated authorization realms. The realms that are delegated for authorization - not the JWT realm - become responsible for populating all of the Elasticsearch user’s values.
The following example shows how you define delegation authorization in the [`elasticsearch.yml`](https://www.elastic.co/elastic/docs-builder/docs/2988/deploy-manage/stack-settings) file to multiple other realms from the JWT realm. A JWT realm named `jwt2` is delegating authorization to multiple realms:
```yaml
xpack.security.authc.realms.jwt.jwt2.authorization_realms: file1,native1,ldap1,ad1
```

You can then use the [create or update role mappings API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-security-put-role-mapping) to map roles to the authorizing realm. The following example maps roles in the `native1` realm for the `principalname1` JWT principal.
```json

{
  "roles" : [ "user" ],
  "rules" : { "all" : [
      { "field": { "realm.name": "native1" } },
      { "field": { "username": "principalname1" } }
  ] },
  "enabled": true
}
```

If realm `jwt2` successfully authenticates a client with a JWT for principal `principalname1`, and delegates authorization to one of the listed realms (such as `native1`), then that realm can look up the Elasticsearch user’s values. With this defined role mapping, the realm can also look up this role mapping rule linked to realm `native1`.

## Applying the `run_as` privilege to JWT realm users

Elasticsearch can retrieve roles for a JWT user through either role mapping or delegated authorization. Regardless of which option you choose, you can apply the [`run_as` privilege](/elastic/docs-builder/docs/2988/deploy-manage/users-roles/cluster-or-deployment-auth/submitting-requests-on-behalf-of-other-users#run-as-privilege-apply) to a role so that a user can submit authenticated requests to "run as" a different user. To submit requests as another user, include the `es-security-runas-user` header in your requests. Requests run as if they were issued from that user and Elasticsearch uses their roles.
For example, let’s assume that there’s a user with the username `user123_runas`. The following request creates a user role named `jwt_role1`, which specifies a `run_as` user with the `user123_runas` username. Any user with the `jwt_role1` role can issue requests as the specified `run_as` user.
```json

{
  "cluster": ["manage"],
  "indices": [ { "names": [ "*" ], "privileges": ["read"] } ],
  "run_as": [ "user123_runas" ],
  "metadata" : { "version" : 1 }
}
```

You can then map that role to a user in a specific realm. The following request maps the `jwt_role1` role to a user with the username `user2` in the `jwt2` JWT realm. This means that Elasticsearch will use the `jwt2` realm to authenticate the user named `user2`. Because `user2` has a role (the `jwt_role1` role) that includes the `run_as` privilege, Elasticsearch retrieves the role mappings for the `user123_runas` user and uses the roles for that user to submit requests.
```json

{
  "roles": [ "jwt_role1"],
  "rules" : { "all" : [
      { "field": { "realm.name": "jwt2" } },
      { "field": { "username": "user2" } }
  ] },
  "enabled": true,
  "metadata" : { "version" : 1 }
}
```

After mapping the roles, you can make an [authenticated call](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-security-authenticate) to Elasticsearch using a JWT and include the `ES-Client-Authentication` header:

```sh
curl -s -X GET -H "Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJhdWQiOlsiZXMwMSIsImVzMDIiLCJlczAzIl0sInN1YiI6InVzZXIyIiwiaXNzIjoibXktaXNzdWVyIiwiZXhwIjo0MDcwOTA4ODAwLCJpYXQiOjk0NjY4NDgwMCwiZW1haWwiOiJ1c2VyMkBzb21ldGhpbmcuZXhhbXBsZS5jb20ifQ.UgO_9w--EoRyUKcWM5xh9SimTfMzl1aVu6ZBsRWhxQA" -H "ES-Client-Authentication: sharedsecret test-secret" https://localhost:9200/_security/_authenticate
```

The response includes the user who submitted the request (`user2`), including the `jwt_role1` role that you mapped to this user in the JWT realm:
```sh
{"username":"user2","roles":["jwt_role1"],"full_name":null,"email":"user2@something.example.com",
"metadata":{"jwt_claim_email":"user2@something.example.com","jwt_claim_aud":["es01","es02","es03"],
"jwt_claim_sub":"user2","jwt_claim_iss":"my-issuer"},"enabled":true,"authentication_realm":
{"name":"jwt2","type":"jwt"},"lookup_realm":{"name":"jwt2","type":"jwt"},"authentication_type":"realm"}
%
```

If you want to specify a request as the `run_as` user, include the `es-security-runas-user` header with the name of the user that you want to submit requests as. The following request uses the `user123_runas` user:
```sh
curl -s -X GET -H "Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJhdWQiOlsiZXMwMSIsImVzMDIiLCJlczAzIl0sInN1YiI6InVzZXIyIiwiaXNzIjoibXktaXNzdWVyIiwiZXhwIjo0MDcwOTA4ODAwLCJpYXQiOjk0NjY4NDgwMCwiZW1haWwiOiJ1c2VyMkBzb21ldGhpbmcuZXhhbXBsZS5jb20ifQ.UgO_9w--EoRyUKcWM5xh9SimTfMzl1aVu6ZBsRWhxQA" -H "ES-Client-Authentication: sharedsecret test-secret" -H "es-security-runas-user: user123_runas" https://localhost:9200/_security/_authenticate
```

In the response, you’ll see that the `user123_runas` user submitted the request, and Elasticsearch used the `jwt_role1` role:
```sh
{"username":"user123_runas","roles":["jwt_role1"],"full_name":null,"email":null,"metadata":{},
"enabled":true,"authentication_realm":{"name":"jwt2","type":"jwt"},"lookup_realm":{"name":"native",
"type":"native"},"authentication_type":"realm"}%
```


## PKC JWKS reloading

JWT authentication supports signature verification using PKC (Public Key Cryptography) or HMAC algorithms.
PKC JSON Web Token Key Sets (JWKS) can contain public RSA and EC keys. HMAC JWKS or an HMAC UTF-8 JWK contain secret keys. JWT issuers typically rotate PKC JWKS more frequently (such as daily), because RSA and EC public keys are designed to be easier to distribute than secret keys like HMAC.
JWT realms load a PKC JWKS and an HMAC JWKS or HMAC UTF-8 JWK at startup. JWT realms can also reload PKC JWKS contents at runtime; a reload is triggered by signature validation failures.
JWT realms can also be configured to reload a PKC JWKS periodically in the background.
<note>
  HMAC JWKS or HMAC UTF-8 JWK reloading is not supported at this time.
</note>

Load failures, parse errors, and configuration errors prevent a node from starting (and restarting). However, runtime PKC reload errors and recoveries are handled gracefully.
All other JWT realm validations are checked before a signature failure can trigger a PKC JWKS reload. If multiple JWT authentication signature failures occur simultaneously with a single Elasticsearch node, reloads are combined to reduce the reloads that are sent externally.
Separate reload requests cannot be combined if JWT signature failures trigger:
- PKC JWKS reloads in different Elasticsearch nodes
- PKC JWKS reloads in the same Elasticsearch node at different times

<important>
  Enabling client authentication (`client_authentication.type`) is strongly recommended. Only trusted client applications and realm-specific JWT users can trigger PKC reload attempts. Additionally, configuring the following [JWT security settings](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2988/reference/elasticsearch/configuration-reference/security-settings#ref-jwt-settings) is recommended:
  - `allowed_audiences`
  - `allowed_clock_skew`
  - `allowed_issuer`
  - `allowed_signature_algorithms`
</important>


## Authorizing to the JWT realm with an HMAC UTF-8 key

The following settings are for a JWT issuer, Elasticsearch, and a client of Elasticsearch. The example HMAC key is in an OIDC format that’s compatible with HMAC. The key bytes are the UTF-8 encoding of the UNICODE characters.
<important>
  HMAC UTF-8 keys need to be longer than HMAC random byte keys to achieve the same key strength.
</important>


### JWT issuer

The following values are for the bespoke JWT issuer.
```js
Issuer:     iss8
Audiences:  aud8
Algorithms: HS256
HMAC UTF-8: hmac-oidc-key-string-for-hs256-algorithm
```


### JWT realm settings

To define a JWT realm, add the following realm settings to [`elasticsearch.yml`](https://www.elastic.co/elastic/docs-builder/docs/2988/deploy-manage/stack-settings).
```yaml
xpack.security.authc.realms.jwt.jwt8.order: 8 
xpack.security.authc.realms.jwt.jwt8.allowed_issuer: iss8
xpack.security.authc.realms.jwt.jwt8.allowed_audiences: [aud8]
xpack.security.authc.realms.jwt.jwt8.allowed_signature_algorithms: [HS256]
xpack.security.authc.realms.jwt.jwt8.claims.principal: sub
xpack.security.authc.realms.jwt.jwt8.client_authentication.type: shared_secret
```


### JWT realm secure settings

After defining the realm settings, use the [`elasticsearch-keystore`](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2988/reference/elasticsearch/command-line-tools/elasticsearch-keystore) tool to add the following secure settings to the Elasticsearch keystore. In Elastic Cloud, you define settings for the Elasticsearch keystore under **Security** in your deployment.
```yaml
xpack.security.authc.realms.jwt.jwt8.hmac_key: hmac-oidc-key-string-for-hs256-algorithm
xpack.security.authc.realms.jwt.jwt8.client_authentication.shared_secret: client-shared-secret-string
```


### JWT realm role mapping rule

The following request creates role mappings for Elasticsearch in the `jwt8` realm for the user `principalname1`:
```json

{
  "roles" : [ "user" ],
  "rules" : { "all" : [
      { "field": { "realm.name": "jwt8" } },
      { "field": { "username": "principalname1" } }
  ] },
  "enabled": true
}
```


### Request headers

The following header settings are for an Elasticsearch client.
```js
Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJpc3M4IiwiYXVkIjoiYXVkOCIsInN1YiI6InNlY3VyaXR5X3Rlc3RfdXNlciIsImV4cCI6NDA3MDkwODgwMCwiaWF0Ijo5NDY2ODQ4MDB9.UnnFmsoFKfNmKMsVoDQmKI_3-j95PCaKdgqqau3jPMY
ES-Client-Authentication: SharedSecret client-shared-secret-string
```

You can use this header in a `curl` request to make an authenticated call to Elasticsearch. Both the bearer token and the client authorization token must be specified as separate headers with the `-H` option:
```sh
curl -s -X GET -H "Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJpc3M4IiwiYXVkIjoiYXVkOCIsInN1YiI6InNlY3VyaXR5X3Rlc3RfdXNlciIsImV4cCI6NDA3MDkwODgwMCwiaWF0Ijo5NDY2ODQ4MDB9.UnnFmsoFKfNmKMsVoDQmKI_3-j95PCaKdgqqau3jPMY" -H "ES-Client-Authentication: SharedSecret client-shared-secret-string" https://localhost:9200/_security/_authenticate
```

If you used role mapping in the JWT realm, the response includes the user’s `username`, their `roles`, metadata about the user, and the details about the JWT realm itself.
```sh
{"username":"user2","roles":["jwt_role1"],"full_name":null,"email":"user2@something.example.com",
"metadata":{"jwt_claim_email":"user2@something.example.com","jwt_claim_aud":["es01","es02","es03"],
"jwt_claim_sub":"user2","jwt_claim_iss":"my-issuer"},"enabled":true,"authentication_realm":
{"name":"jwt2","type":"jwt"},"lookup_realm":{"name":"jwt2","type":"jwt"},"authentication_type":"realm"}
```