# Client Assertion

{% hint style="info" %}
***This page must be considered part of the iSHARE Framework***

*This page is considered normative and is therefore compliant with RFC 2119.*
{% endhint %}

This page defines the JWT payload that should be provided to generate an iSHARE JWT client assertion for the [access token endpoint.](https://gitlab.com/ishare-foundation/cab/developer-portal/-/blob/v2.2/all-roles-common-endpoints/access-token-m2m%20\(1\).md)

## JWT Payload

Instead of the default [iSHARE JWT ](/version-2.2/reference/ishare-jwt.md)payload requirements, the following apply:

* The `iss` and `sub` claims MUST contain a valid [Party Identifier](https://framework.ishare.eu/detailed-descriptions/functional/functional-requirements-per-role/party-identification) of the client that wishes to authenticate.
* The `aud` claim MUST contain only a valid [Party Identifier](https://framework.ishare.eu/detailed-descriptions/functional/functional-requirements-per-role/party-identification) of the party that authenticates the client. Including multiple audiences creates a risk of impersonation and is therefore not allowed.

In OAuth 2.0 clients are generally pre-registered. Since in iSHARE servers interact with clients that may have been previously unknown, this is not a workable requirement. Therefore iSHARE implements a generic client identification and authentication scheme, based on iSHARE whitelisted PKIs.

Since OAuth 2.0 doesn’t specify a PKI based authentication scheme, but OpenID Connect 1.0 does, iSHARE chooses to use the scheme specified by OpenID Connect in all use cases. This is preferred above defining a new proprietary scheme.

Example Client Assertion JWT Payload:

```json
{
  "iss": "did:ishare:EU.NL.NTRNL-10000001",
  "sub": "did:ishare:EU.NL.NTRNL-10000001",
  "aud": "did:ishare:EU.NL.NTRNL-10000000",
  "jti": "378a47c4-2822-4ca5-a49a-7e5a1cc7ea59",
  "exp": 1504683475,
  "iat": 1504683445
}
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://dev.ishare.eu/version-2.2/reference/ishare-jwt/client-assertion.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.