Commit Graph
2 Commits
Author SHA1 Message Date
jaap-jan a878c2b6bb Add the server client and client-side enrollment
A typed client over DodoSSH.Contracts, and the orchestration that turns a
passphrase into an enrolled identity: generate keys, have the identity
provider sign over them, wrap the bundle three ways, create the personal
vault, publish.

Ordering here is forced, not chosen. The secret bundle's AAD binds to the
server-assigned user id, so /me has to be read before anything can be
wrapped -- which is exactly why /me provisions the account and returns its id
even while reporting that enrollment is required. That constraint was
designed into the server earlier; this is the first code that depends on it.

The grant tuple now has a real canonical encoding (crypto.md 7.3) rather
than the placeholder signature I would otherwise have had to invent and then
keep. ยง7 named the tuple without specifying how to encode it; this fills that
in with the same conventions as 7.1, and the self-grant at enrollment is
already in its final format. The signature covers SHA-256(wrappedKey) rather
than the key, so a verifier can check attribution without holding the vault
key at all.

The most valuable tests are the negative ones about the request body: the
server is meant to be unable to read what it stores, and a refactor that put
a passphrase or a private key into the enrollment request would be invisible
to every other test in the repository. So one asserts the body contains
neither the passphrase, the recovery code, nor any private key in base64 or
hex. Another opens the same bundle three ways -- passphrase, recovery code and
device key -- which is what makes a passphrase change a one-row update.

ClientEnrollment depends on IKeyBindingAuthorizer rather than the whole
OidcClient. It needs exactly one capability, and depending on the full client
would drag discovery and token exchange into every test of key binding.

Two things fixed while building it. The recovery code buffer was sized one
separator short, so every enrollment threw IndexOutOfRange -- caught
immediately because nine of ten tests failed identically. And the crypto
enum collided with Domain.GrantKind in the server, so it is GrantPurpose
there; the numeric values still have to match, which the doc and a test both
say.

448 tests pass, zero warnings on a clean rebuild, format clean.
2026-07-28 22:42:56 +02:00
jaap-jan 94f66be5e8 Add the OIDC client: PKCE loopback sign-in and the key binding flow
Authorization Code with PKCE on a loopback redirect, per RFC 6749, RFC 7636
and RFC 8252. Zero package references: the flow is fully specified, and the
one thing a library would own for us -- nonce generation and validation -- is
exactly what the key binding needs to control. Duende's OidcClient generates
and validates its own nonce as an internal detail, and the binding requires
the nonce be a specific value: the hash of the key statement being enrolled.
Fighting that is worse than owning the flow.

AuthorizeKeyBindingAsync is the client half of the primary trust anchor. It
runs a second authorization with nonce set to the statement hash and
prompt=login, so the ID token that returns is the provider's signature over
exactly those public keys, attesting to a user present now rather than to a
session opened at some unknown earlier time. It requests only openid -- a
second refresh token would be one more long-lived credential for no benefit
-- and rejects a token whose nonce is not the one it asked for, because
enrolling that would store evidence verifying against keys we are not
publishing.

The nonce is read without validating the ID token's signature. Sanctioned by
OIDC Core 3.1.3.7: for a token received by direct communication with the
token endpoint, TLS server authentication may stand in for signature
checking. That reasoning does not extend to another user's binding, which
arrives via the DodoSSH server and must be verified against JWKS fetched
directly -- the directory work in M3.

Raw TcpListener rather than HttpListener for the redirect: an ephemeral port
can be bound and read atomically instead of picking one and hoping it is
still free, there is no HTTP.SYS URL-ACL question on Windows, and the whole
surface is one request line. It answers 404 on other paths and keeps
waiting, because a browser asks for /favicon.ico first and treating that as
the callback would abort every sign-in. 127.0.0.1 rather than localhost: RFC
8252 permits either, but the name resolves through the hosts file.

20 tests, driving the real listener over TCP with a fake browser that
actually fetches the redirect -- injecting a fabricated callback would skip
the parsing, path filtering and response writing that can break. Mostly
negative, because the loopback port is reachable by every local process: a
response with the wrong state is rejected *and* never reaches the token
endpoint, metadata declaring an issuer other than its own authority is
rejected (RFC 8414 3.3, without which a mix-up attack works), a provider
offering only 'plain' is fatal rather than a silent downgrade, and the
verifier sent is checked against the challenge advertised so PKCE is not
theatre that only fails in production.

Two bugs caught by writing the tests: the authorize URL builder dropped
client_id entirely after a refactor, and CancellationTokenSource.CancelAfter
has no TimeProvider overload -- so the browser timeout is now constructed
with the clock and a test can advance it instead of waiting five minutes.
2026-07-28 21:13:35 +02:00