Critical-path piece that turns a fresh TCP stream into an
authenticated session. With this slice landed, an `AsbClient` can
now do `send_preamble().await? -> connect().await? -> register_items()`
end-to-end against a peer.
Operations API additions:
* `build_connect_request_body(connection_id, public_key)` — first op
on a fresh session. **Unsigned** (no ConnectionValidator header)
because the authenticator hasn't received the service key yet.
Wire shape: `<ConnectRequest xmlns="…messages/20111111">
<ConnectionId>{guid-text}</ConnectionId>
<ConsumerPublicKey><Data>{pubkey-bytes}</Data></ConsumerPublicKey>
</ConnectRequest>` per `AsbContracts.cs:78-86`.
* `build_authenticate_me_request_body(data, iv)` — second op,
**one-way + signed with `forceHmac=true`** per `MxAsbDataClient.cs
:106-111`. Carries the encrypted `local_pub || remote_pub` blob
produced by F23's `create_authentication_data()`.
* `ConnectResponse { service_public_key, service_authentication_data,
connection_lifetime }` + `AuthenticationDataBytes { data, iv }`.
* `decode_connect_response(body, dict)` — extracts ServicePublicKey
(required), optional ServiceAuthenticationData, optional
ConnectionLifetime. The lifetime's `:V2` suffix is what F23
inspects to toggle Apollo (raw AES) vs Baktun (deflate-then-AES)
encryption.
Client API addition:
* `AsbClient::connect()` — orchestrates the full handshake:
1. Build + send ConnectRequest (unsigned) carrying our DH public
key + connection-id GUID.
2. Decode ConnectResponse.
3. `authenticator.accept_connect_response(...)` — feeds the
service public key + lifetime into F23 so it derives the
shared secret and picks Apollo/Baktun.
4. `authenticator.create_authentication_data()` — encrypts
`local_pub || remote_pub` under the derived AES key.
5. Send AuthenticateMeRequest (one-way, signed with HMAC-SHA1
forced).
Returns the `ConnectResponse` so callers can inspect the
negotiated connection lifetime.
6 new tests:
* ConnectRequest carries hyphenated GUID + raw public-key bytes.
* AuthenticateMe carries Data + IV bytes in order.
* ConnectResponse round-trip with all optional fields populated.
* ConnectResponse round-trip without optional fields.
* ConnectResponse decoder surfaces MissingField when
ServicePublicKey is absent.
* End-to-end client::connect handshake via `tokio::io::duplex`
peer that synthesises a ConnectResponse using bob's public key
(so DH shared-secret derivation actually works) and drains the
AuthenticateMe one-way SizedEnvelope.
Wire-byte caveat documented inline: WCF XML serialization may add
`xsi:type` attributes / distinct namespaces around <PublicKey> /
<AuthenticationData>; this builder ships the simplest plausible
shape and the live-probe iteration will reconcile.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Joseph Doherty
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