issuer.rest.walnut.js/README.md

issuer@oauth3.org (js)
======================

Implementation of server-side RESTful OAuth3 issuer APIs.

These are the OAuth3 APIs that allow for creation and retrieval of public keys
used for signing identity tokens.

"issuer" is somewhat of a misnomer from the OIDC breakdown of authentication /
authorization parties. What we mean by "issuer" here is actually more like
"notary" or "authorized verifier". However, since the "iss" field is already
standardized, we keep that name for consistency.

What's to be implemented:

Looking at <https://oauth3.org/.well-known/oauth3/directives.json>, the core
issuer components are these:

```
api:                    api.:hostname
create_jwk:             :scheme//:hostname/api/issuer@oauth3.org/jwks/:sub
jwks:                   :scheme//:hostname/api/issuer@oauth3.org/jwks/:thumbprint.json
grants:                 :scheme//:hostname/api/issuer@oauth3.org/grants/:sub/:azp?
credential_meta:        :scheme//:hostname/api/issuer@oauth3.org/logins/meta/:type/:id
credential_otp:         :scheme//:hostname/api/issuer@oauth3.org/otp
authorization_decision  :scheme//:hostname/api/issuer@oauth3.org/authorization_decision
authorization_dialog    :scheme//:hostname/api/issuer@oauth3.org/authorization_dialog
logout                  :scheme//:hostname/api/issuer@oauth3.org/#/logout
```

No `access_token` endpoint is strictly necessary. Since clients can create and
manage their identity, the can sign create their own tokens. If the identity is
stored on the issuer, then the issuer can also sign tokens. Doing so gives full
control of all resources owned by the subject "sub" to the issuer "iss".

```
create_sub:       :scheme//:hostname/api/issuer@oauth3.org/subs/:secret/:sub
```

And here are some others that are useful, but could be implemented differently
without breaking the protocol.

```
credential_create: :scheme//:hostname/api/issuer@oauth3.org/logins
credential_meta: :scheme//:hostname/api/issuer@oauth3.org/logins/meta/:type/:id
credential_otp: :scheme//:hostname/api/issuer@oauth3.org/otp
```

subject
-------

The `sub` field must be `sha256(secret + ':' + azp)`.

Example:

```js
var secret = '8f7acd369764df342d1581872ff5f70fcc261aa116b3c41dee7ca3474ee2020f' // cryto.randomBytes(32).toString('hex')
var sha256 = cryto.createHash('sha256');
sha256.update(new Buffer(secret, 'hex'));
sha256.update(':' + 'example.com');

var sub = sha256.digest('hex');
```

This way any issuer can transfer ownership of identity to any other issuer and
deterministically reproduce the ppid by virtue of the secret identity of the
subject and the public identity of the authorized party and the key is known to
be good if the issuer "iss" can supply the public key that verifies the token,
identified by its thumbprint "kid" (which the issuer knows without revealing
its ppid of the subject and without the authorized party needing to reveal its
ppid of the subject.

jwks
----

The jwk endpoint needs to reveal the jwk by thumbprint as well as some