[Openid-specs-fapi] Issue #163: more description of the security model (openid/fapi)

[Joseph Heenan]

New issue 163: more description of the security model
https://bitbucket.org/openid/fapi/issues/163/more-description-of-the-security-model

Joseph Heenan:

As per discussion on https://bitbucket.org/openid/fapi/issues/150/mandate-at_hash-check-in-the-id-token-from it may be worth adding a description of the security model:


> I wonder if we should explain the full security model somewhere, unless it's already covered somewhere else?

> The way I see it there's a chain here where a weakness at any point could allow a rogue access token in:

> discovery - protected by TLS cert, but I presume a client generally only fetches this once

> jwks_uri - obtained from discovery, protected by TLS cert and refreshed frequently

> id_token - validated by keys from jwks_uri

> access token - validated by hash from id_token

> That would tend to imply that we should make it clear that discovery & jwks_uri endpoints are both on a 'secure' server and (as Nat had suggested before) that people should look at techniques like TLS certificate pinning, DNSSEC, etc, etc.

> It all depends on how far we want to go. e.g. openbanking neither recommend certificate pinning (at least as far as I can see in the security specification), and I believe all bank jwks uris are hosted on a host under openbanking.org.uk, and that domain doesn't appear to have DNSSEC setup.