geteduroam

API for obtaining client certificates

The server on demo.eduroam.no can be accessed directly by a user, where he is required to authenticate and then allowed to download a client certificated, packed in a profile (eap-metadata, mobileconfig, pkcs12, pem). But not all platforms have support for importing configuration files; some operating systems only have internal APIs for configuring wireless profiles (e.g. Windows and Android). For these platforms, the server allows retrieving profiles through a web API. This is a description of the API.

Discovery

For discovery, use the discovery JSON file hosted at https://discovery.eduroam.app/v1/discovery.json

TODO document the format of the discovery. It is rather straightforward, but explicit documentation is better

Authorization endpoint

Build a URL for the authorization endpoint; take the authorization_endpoint string from the discovery, and add the following GET parameters:

  • response_type (set to code)
  • code_challenge_method (set to S256)
  • scope (choose between eap-metadata and mobileconfig)
  • code_challenge (a code challenge, as documented in RFC7636 section 4)
  • redirect_uri (where the user should be redirected after accepting or rejecting your application, GET parameters will added to this URL by the server)
  • client_id (your client ID as known by the server)
  • state (a random string that will be set in a GET parameter to the redirect_uri, for you to verify it’s the same flow)

You have created a URL, for example:

https://demo.eduroam.no/authorize.php?response_type=code&code_challenge_method=S256&scope=eap-metadata&code_challenge=E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM&redirect_uri=http%3A%2F%2Flocalhost%3A1080%2Fcallback&client_id=00000000-0000-0000-0000-000000000000&state=0

You open a local webbrowser to this URL on the users' device and listen on the redirect_uri for a request to return. Upon receiving a request, reclaim focus to your application and handle the request. You may receive these GET parameters:

  • code (a code that you can use on the token endpoint)
  • error (an error message that you can present to the user)
  • state (the same value as your earlier state GET parameter)

As a reply to this request, you may simply return a message to the user stating that he should return to the application. Depending on the platform, you may also return code to trigger a return to the application.

Token endpoint

The token endpoint requires a code, which you obtain via the Authorization endpoint. Use the token_endpoint string from the discovery.

You need the following POST parameters:

  • grant_type (set to authorization_code)
  • code (the code received from the authorization endpoint)
  • redirect_uri (repeat the value used in the previous request, as mandated by RFC7636)
  • client_id (repeat the value used in the previous request, as mandated by RFC7636)
  • code_verifier (a code verifier, as documented in RFC7636 section 4)

You get back a JSON dictionary, containing the following keys:

  • access_token
  • token_type (set to Bearer)
  • expires_in (validity of the access_token in seconds)

Example HTTP conversation

POST /token.php HTTP/1.1
Accept: application/json
Content-Type: application/x-www-form-urlencoded
Content-Length: 209

grant_type=authorization_code&code=v2.local.AAAAAA&redirect_uri=http%3A%2F%2Flocalhost%3A1080%2Fcallback&client_id=00000000-0000-0000-0000-000000000000&code_verifier=dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk

HTTP/1.1 200 OK
Cache-Control: no-store
Content-Type: application/json;charset=UTF-8
Pragma: no-cache

{
    "access_token": "v2.local.AAAAA…==",
    "token_type": "Bearer",
    "expires_in": 3600
}

Generator endpoint

The generator requires an access_token, as bearer. You’ve obtained this from the token endpoint. For the URL to the generator, use the generator_endpoint string from the discovery.

POST /generate.php? HTTP/1.1
Accept: application/x-eap-config
Authorization: Bearer AAAAAA…==
Content-Type: application/x-www-form-urlencoded
Content-Length: 19

format=eap-metadata

HTTP/1.1 200 OK
Cache-Control: no-store
Content-Disposition: attachment; filename="johndoe.xml"
Content-Type: application/eap-config
Pragma: no-cache

<?xml version="1.0" encoding="utf-8"?>
…
Last updated on 7 Sep 2020