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I worked on an identity provider platform and this was always such a huge problem. Many application developers treat authentication as an all or nothing proposi

I worked on an identity provider platform and this was always such a huge problem. Many application developers treat authentication as an all or nothing proposition: either a user is authenticated or they are not, but the reality is that authorization is truly hard part and often completely overlooked. This is especially true in Oauth2/OIDC schemes where JWT bearer tokens are issues. At that point you are delegating token validation and access control out to all clients. Even if you are using opaque tokens to prevent basic token verification issues, you still just end up doing the token validation for the client. They still are responsible for access controls on specific resources.

fendy3002 5y ago
Out of topic, I use oidc provider (keycloak). I fetch the public key from oidc provider then verify the bearer token with it. Then use the permissions field to authorize users based on their permission. Does my approach correct / suffice?
- thinkharderdev 5y ago
  In general, yes that is exactly what you are supposed to do. But the really hard part is determining what scopes (which is what I assume you are referring to here as permissions) allow access to which resources/actions.
- kerng 5y ago
  I'm always wondering what the right approach is when using third party authentication. Use scopes or just store user identifier and permission in your own database. I have seen the two authorization approaches get co-mingled, which leads to issues. Also, often scopes are two large.. but that's mostly an implementation choice, like read all, rather than allow access to only a specific item - maybe scopes are just less easy to handle/maintain/define for the average developer.
  - fendy3002 5y ago
    > I have seen the two authorization approaches get co-mingled, which leads to issues. Correct, for me this is a must avoid at all costs. I can't imagine how hard / complex it is to manage / audit two authorization system. Unless your application need more detailed permission / smaller scope, example later. Personally I just use the one that comes from the identity provider. In my case, keycloak's model is sufficient for my use case. And you're right, scopes are hard and unless it's global scope, you'll need to roll your own. One good example case is github/gitlab. Global scope is the administrator access, and it's easy to set it in identity provider (as "administrator" access maybe). However for each group / repository level, you'll need to roll your own validation. EDIT: More often than not, it comes into business domain than technical / programming one. If you're not experienced with the business domain, no wonder you'll find it hard.
- blablabla123 5y ago
  That's the idea of the JWT, no DB query or in this case additional network request needed to authenticate. Depending on your use case it's worth thinking about the expiration time. I assume that's checked in your client but do you also need to invalidate tokens or downgrade permissions before they expire? In that case you might want to work with smaller expiration times or get a denylist.
- Rels 5y ago
  Yes. Assuming you also validated the expiry date. Assuming you also verified that the issuer matched the expected one, and that you didn't fetch keys based on the issuer that is in the token. Also assuming that the crypto alg is the one you expected.
imglorp 5y ago
> the reality is that authorization is truly hard part Not only is it under often estimated, but in many orgs it's also reduced to a single checkbox item on someone's go-to-market slide. ":thumbsup - we're secure now!". Instead it needs to be a constant part of the culture, in every feature from the first, and ongoing thereafter.
spinny 5y ago
Maybe this stems from newbie developers thinking that authentication == authorization

fendy3002 5y ago

Out of topic, I use oidc provider (keycloak). I fetch the public key from oidc provider then verify the bearer token with it. Then use the permissions field to authorize users based on their permission. Does my approach correct / suffice?

thinkharderdev 5y ago
In general, yes that is exactly what you are supposed to do. But the really hard part is determining what scopes (which is what I assume you are referring to here as permissions) allow access to which resources/actions.
kerng 5y ago
I'm always wondering what the right approach is when using third party authentication. Use scopes or just store user identifier and permission in your own database. I have seen the two authorization approaches get co-mingled, which leads to issues. Also, often scopes are two large.. but that's mostly an implementation choice, like read all, rather than allow access to only a specific item - maybe scopes are just less easy to handle/maintain/define for the average developer.
- fendy3002 5y ago
  > I have seen the two authorization approaches get co-mingled, which leads to issues. Correct, for me this is a must avoid at all costs. I can't imagine how hard / complex it is to manage / audit two authorization system. Unless your application need more detailed permission / smaller scope, example later. Personally I just use the one that comes from the identity provider. In my case, keycloak's model is sufficient for my use case. And you're right, scopes are hard and unless it's global scope, you'll need to roll your own. One good example case is github/gitlab. Global scope is the administrator access, and it's easy to set it in identity provider (as "administrator" access maybe). However for each group / repository level, you'll need to roll your own validation. EDIT: More often than not, it comes into business domain than technical / programming one. If you're not experienced with the business domain, no wonder you'll find it hard.
blablabla123 5y ago
That's the idea of the JWT, no DB query or in this case additional network request needed to authenticate. Depending on your use case it's worth thinking about the expiration time. I assume that's checked in your client but do you also need to invalidate tokens or downgrade permissions before they expire? In that case you might want to work with smaller expiration times or get a denylist.
Rels 5y ago
Yes. Assuming you also validated the expiry date. Assuming you also verified that the issuer matched the expected one, and that you didn't fetch keys based on the issuer that is in the token. Also assuming that the crypto alg is the one you expected.

imglorp 5y ago

> the reality is that authorization is truly hard part Not only is it under often estimated, but in many orgs it's also reduced to a single checkbox item on someone's go-to-market slide. ":thumbsup - we're secure now!". Instead it needs to be a constant part of the culture, in every feature from the first, and ongoing thereafter.

spinny 5y ago

Maybe this stems from newbie developers thinking that authentication == authorization