protected void validateNonce(final StateData stateData, final IAuthenticationResult authData) {
        final String idToken = authData.idToken();
        if (logger.isDebugEnabled()) {
            logger.debug("idToken: {}", idToken);
        }
        try {
            final JWTClaimsSet claimsSet = JWTParser.parse(idToken).getJWTClaimsSet();
            if (claimsSet == null) {

1. The id_token is an identifier that is hard to guess. For example, a randomly generated string of sufficient length, that the server handling the protected resource can use to lookup the associated authorization information.

- The redirection URI (callback handler) receives the OAuth2 callback, verifies the state parameter, and obtains a Token.
- Using the id_token the callback handler further talks to Google OAuth2 Token URL to obtain an JWT id_token.
- Once obtained the JWT id_token is further sent to STS endpoint i.e MinIO to retrieve temporary credentials.
- Temporary credentials are displayed on the browser upon successful retrieval.

>
> - [**AssumeRole**](https://github.com/minio/minio/blob/master/docs/sts/assume-role.md)
> - [**AD/LDAP**](https://github.com/minio/minio/blob/master/docs/sts/ldap.md)

time="2020-07-12T20:45:50Z" level=info msg="config connector: mock"
time="2020-07-12T20:45:50Z" level=info msg="config connector: local passwords enabled"
time="2020-07-12T20:45:50Z" level=info msg="config response types accepted: [code token id_token]"
time="2020-07-12T20:45:50Z" level=info msg="config using password grant connector: local"
time="2020-07-12T20:45:50Z" level=info msg="config signing keys expire after: 3h0m0s"

```

### Using WebIdentiy API

On another terminal run `web-identity.go` a sample client application which obtains JWT id_tokens from an identity provider, in our case its Keycloak. Uses the returned id_token response to get new temporary credentials from the MinIO server using the STS API call `AssumeRoleWithWebIdentity`.

```

	// code, which we now have in `lastReq`. Exchange it for a JWT id_token.
	q := lastReq.URL.Query()
	// fmt.Printf("lastReq.URL: %#v q: %#v\n", lastReq.URL, q)
	code := q.Get("code")
	oauth2Token, err := oauth2Config.Exchange(ctx, code)
	if err != nil {
		return "", fmt.Errorf("unable to exchange code for id token: %v", err)
	}

	rawIDToken, ok := oauth2Token.Extra("id_token").(string)
	if !ok {

    protected LoginCredential processCallback(final HttpServletRequest request, final String code) {
        try {
            final TokenResponse tr = getTokenUrl(code);

            final String[] jwt = ((String) tr.get("id_token")).split("\\.");
            final String jwtHeader = new String(decodeBase64(jwt[0]), Constants.UTF_8_CHARSET);
            final String jwtClaim = new String(decodeBase64(jwt[1]), Constants.UTF_8_CHARSET);

- Check that `account` client_id has the role 'admin' assigned in the "Service Account Roles" tab.

After that, you will be able to obtain an id_token for the Admin REST API using client_id and client_secret:

```
curl \
  -d "client_id=<YOUR_CLIENT_ID>" \
  -d "client_secret=<YOUR_CLIENT_SECRET>" \
  -d "grant_type=client_credentials" \