Our application uses oauth2 & openid connect for auth&auth. It's built using an angular client that calls a REST API. I would like to know how to authorize access to the API, based on the possession of an unguessable url.
I'll explain this a little more. In the application, a user can invite another user. When this happens, an email is sent to the second user. When user 2 clicks a link in the email, he is sent to a webpage with details about the invitation.
Only user 2 should be allowed to see the invitation page. I was planning to solve this by using an 'unguessable url' in the email. Upon visiting the url, the user must somehow be authorized to fetch the invitation details from the API.
The question: how do I authorize a user, based on knowing the unguessable url? How do I assign a claim when the page is loaded, and how do I verify this claim in the API call that follows? The only solution I see, is to set a cookie containing a token. But this is not in line with our existing auth mechanism. I prefer not writing my own token validation code, and let the Identity Provider handle this.
Additional info: user 2 may or may not have an account in the system, and he may or may not be logged in. Neither should prevent the user from seeing the invitation details. In other words: a totally unknown user should be able to see the page. The knowledge of the url should be the only requirement.
Any solution to this problem? Or am I handling it all wrong?
After asking around, the general consensus is to NOT let the external auth mechanism take care of this, but to validate the link ourselves.
The solution is to turn the unguessable part of the url (the 'link id') in some kind of token, which can be validated upon calling the API. This is done by the API itself, not by the Identity Server.
Applied to the invitation issue: when an invitation is created, store the link id together with some info, i.e. what kind of access it allows (invitation access) and the id of the invitation. When the user calls the API to get the invitation, pass the link id for validation. Match the invitation id with the invitation id stored in the link, and if it doesn't, throw an error.