Authorize Endpoint

The authorize endpoint can be used to request tokens or authorization codes via the browser. This process typically involves authentication of the end-user and optionally consent.

Note

IdentityServer supports a subset of the OpenID Connect and OAuth 2.0 authorize request parameters. For a full list, see here.

client_id
identifier of the client (required).
scope
one or more registered scopes (required)
redirect_uri
must exactly match one of the allowed redirect URIs for that client (required)
response_type

id_token requests an identity token (only identity scopes are allowed)

token requests an access token (only resource scopes are allowed)

id_token token requests an identity token and an access token

code requests an authorization code

code id_token requests an authorization code and identity token

code id_token token requests an authorization code, identity token and access token

response_mode
form_post sends the token response as a form post instead of a fragment encoded redirect (optional)
state
identityserver will echo back the state value on the token response, this is for round tripping state between client and provider, correlating request and response and CSRF/replay protection. (recommended)
nonce

identityserver will echo back the nonce value in the identity token, this is for replay protection)

Required for identity tokens via implicit grant.

prompt

none no UI will be shown during the request. If this is not possible (e.g. because the user has to sign in or consent) an error is returned

login the login UI will be shown, even if the user is already signed-in and has a valid session

code_challenge
sends the code challenge for PKCE
code_challenge_method
plain indicates that the challenge is using plain text (not recommended) S256 indicates the the challenge is hashed with SHA256
login_hint
can be used to pre-fill the username field on the login page
ui_locales
gives a hint about the desired display language of the login UI
max_age
if the user’s logon session exceeds the max age (in seconds), the login UI will be shown
acr_values

allows passing in additional authentication related information - identityserver special cases the following proprietary acr_values:

idp:name_of_idp bypasses the login/home realm screen and forwards the user directly to the selected identity provider (if allowed per client configuration)

tenant:name_of_tenant can be used to pass a tenant name to the login UI

Example

GET /connect/authorize?
    client_id=client1&
    scope=openid email api1&
    response_type=id_token token&
    redirect_uri=https://myapp/callback&
    state=abc&
    nonce=xyz

(URL encoding removed, and line breaks added for readability)

IdentityModel

You can programmatically create URLs for the authorize endpoint using the IdentityModel library:

var request = new RequestUrl(doc.AuthorizeEndpoint);
var url = request.CreateAuthorizeUrl(
    clientId:     "client",
    responseType: OidcConstants.ResponseTypes.CodeIdToken,
    responseMode: OidcConstants.ResponseModes.FormPost,
    redirectUri: "https://myapp.com/callback",
    state:       CryptoRandom.CreateUniqueId(),
    nonce:       CryptoRandom.CreateUniqueId());

..and parse the response:

var response = new AuthorizeResponse(callbackUrl);

var accessToken = response.AccessToken;
var idToken = response.IdentityToken;
var state = response.State;