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jaap-jan e3fd3e1728 Sync and authenticate with SSH keys on the client 
Completes the client half of SSH keys: they sync alongside hosts, appear in
their own list, and can be selected to authenticate a connection instead of
typing a password.

The reconciler and the repository were Host-typed throughout, so the choice was
to generalise them or to keep a second copy per item type. Generalised, because
ItemReconciler's whole premise is that the pull and the push paths must answer
the same collision the same way — two copies would drift the first time one of
them was fixed. What is genuinely per-type now arrives through
IItemKind<TSecret>: the cipher, the merge, the plaintext columns, and the noun
to use when telling a person what happened to their item. Generic where the
server's IItemKind is not, and for the reason that reverses there — the client
needs the concrete type, because it merges field by field.

The pull filter is derived from the same registry that builds the reconcilers.
That is the specific failure being designed out: an item type that encrypts,
merges and lists perfectly and is never once requested from the server, so it
works on the machine that made it and exists nowhere else.

No client cache migration. The item table's primary key and the outbox's unique
index already carry the entity type, and AadResourceTypes already mapped SshKey
— so a host and a key may share an id and never see each other's rows, which
SshKeySyncTests now arranges deliberately.

A key hands the server nothing in plaintext. There is a public_key_fingerprint
column and it would be accepted; leaving it null is deliberate. A fingerprint is
not secret but it is a stable identifier for a key pair, so filling it would let
an operator tell which of their users hold the same key and correlate one across
vaults, for a column nothing reads. The design allows itself one plaintext
concession — the relay address, which the relay cannot work without — and this
is not that.

A key is chosen per connection rather than bound to a host, which works the way
ssh -i does. Binding one needs a field on HostSecret and therefore a payload
schema bump, which makes every host written afterwards read-only on an older
build; worth doing deliberately rather than as a side effect of adding keys.

Three things this found, all of them by being falsified rather than by review:

- Making the reconciler generic silently turned a record comparison into
  reference equality, because == on a type parameter is not value equality. The
  effect would have been a conflict recorded on every pass for an unacknowledged
  create that had in fact landed. Sabotaging the fix left all 73 tests passing —
  nothing covered that branch — so ConflictMatrixTests now has
  AnUnacknowledgedCreateThatDidLand_IsDroppedQuietly, which fails without it.

- A test asserting that a blank passphrase reaches SSH.NET as null was vacuous:
  it exercised the editor, not the credential path, and passed with the guard
  deleted. Resolved by making SshKeySecret.Passphrase normalise an empty string
  to null, so there is one spelling of one state — which also keeps two clients
  from producing different payload bytes for an identical key. That exposed a
  wider gap: SshKeySecret, its codec and its merge had no direct unit tests at
  all. They have 25 now.

- The reason first given for that normalisation was false. It claimed SSH.NET
  rejects a passphrase supplied for an unprotected key; measured against a real
  sshd it ignores it and authenticates anyway. Corrected everywhere it was
  stated and recorded in docs/platform-flags.md. The same test file also closes
  a real hole: SshPrivateKeyCredential had never been exercised against a
  server, because the existing key test builds SSH.NET's auth method directly
  and bypasses the path a vault-held key actually takes.

Only one editor may be open at a time. Both sit in the same 340-pixel column as
Auto rows and their heights together exceed it at the window's minimum size, so
two open editors put the lower one's Save and Cancel past the bottom edge — the
same failure this window already shipped once with the setup screens. Expressed
as a state rule because that is the only form of it this repository can check:
nothing here loads a .axaml. The refusal keeps what was typed, since in the key
editor that is a pasted private key the user may have nowhere else.

The end-to-end slice now carries a key as well as a host, so both item types go
through the real API, the real PostgreSQL and the real crypto in one pass — the
three hand-kept mappings between enums that do not line up are the reason that
is worth doing rather than trusting the unit suites.

735 tests green, including the container-backed SSH and end-to-end suites. Zero
warnings, dotnet format clean.
2026-07-29 20:27:23 +02:00

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# DodoSSH
A self-hosted, team-oriented SSH client with an end-to-end encrypted vault.
Manage hosts, credentials and keys in a desktop app; sync them across your devices and share
them with teammates through a server you run yourself. **The server stores ciphertext and never
holds a key** — the operator cannot read the credentials it stores.
> Status: early development. See [the milestone plan](#milestones) for what exists today.
## Why
Teams either scatter SSH credentials across individual `~/.ssh` directories with no sharing
story, or pay per-seat for a hosted product that holds their infrastructure credentials.
DodoSSH keeps the convenience of a synced, shareable vault while remaining self-hostable and
zero-knowledge.
## Architecture
| Component | Choice |
| --- | --- |
| Backend | ASP.NET Core on .NET 10, PostgreSQL + EF Core |
| Client | Avalonia (C#) for Windows/Linux/macOS; terminal pane is a WebView running xterm.js |
| Auth | OIDC, provider-agnostic (Entra ID, Keycloak, Auth0, Authentik) |
| Vault | End-to-end encrypted; X25519 + Ed25519 + XChaCha20-Poly1305, Argon2id unlock |
| Connections | Client-direct SSH by default, with an optional raw-TCP server relay |
Three consequences worth knowing before you read further:
- **Revocation is not retroactive.** A removed member keeps what they already downloaded. The
real remediation is rotating the SSH credential, so offboarding is built around a rotation
checklist rather than a button that implies more than it delivers.
- **No session recording in relay mode.** The relay forwards SSH ciphertext, so it cannot see
commands. That is the cost of the relay not being able to read your traffic.
- **Locking the vault does not close your shells.** Lock closes the vault and zeroes every key it
held; a session that authenticated before it keeps running, because the remote host never
consulted the vault and the credential was already spent. That is deliberate — you lock when you
walk away from the machine, which is exactly when a long upgrade or transfer is most likely to be
in flight, and an idle auto-lock that killed it would be worse than the exposure it removed. The
honest reading is that *locked* describes the vault and not this machine's access to your hosts.
The unlock screen therefore shows how many shells are still connected, and quitting DodoSSH is
what ends them.
The reasoning behind each major decision is recorded in [`docs/adr/`](docs/adr/), starting with
[the E2EE trust model](docs/adr/0001-e2ee-trust-model.md).
## Repository layout
```
src/
DodoSSH.Contracts DTOs shared with the client — the real API contract
DodoSSH.Crypto DSH1 envelope, AAD derivation, the key hierarchy
DodoSSH.Domain entities and invariants, no EF
DodoSSH.Infrastructure DbContext, configurations, migrations
DodoSSH.Api the server
DodoSSH.Client.Auth OIDC code+PKCE on a loopback redirect, and the key binding
DodoSSH.Client.Api the typed server client, and client-side enrollment
DodoSSH.Client.Domain the decrypted item model and the three-way merge — no I/O at all
DodoSSH.Client.Storage the local cache: ciphertext mirror, outbox, offline unlock material
DodoSSH.Client.Sync the pull/apply/push loop and the conflict policy
DodoSSH.Client.Session where a profile lives, unlocking it, and getting one in the first place
DodoSSH.Client.Ssh connections, PTY shells, host key trust
DodoSSH.Client.Terminal the loopback data plane and credit-based flow control
DodoSSH.Client.App Avalonia; the only project that knows about a UI toolkit
tests/ one test project per source project
docs/adr/ architecture decision records
```
Everything under `src/DodoSSH.Client.*` except `App` is deliberately free of Avalonia. That is the
seam that lets the SSH layer, the terminal's flow control and the OIDC flow be tested without a UI
toolkit or a browser engine — which is most of why they are testable at all.
## Building
Requires the .NET SDK pinned in [`global.json`](global.json) (10.0.x).
```bash
dotnet build DodoSSH.slnx
```
```bash
dotnet test DodoSSH.slnx
```
The tests need a Docker daemon. Everything that touches the database, the identity provider or an SSH
server uses Testcontainers rather than a stub or a shared instance, so there is nothing to start first and
nothing to clean up after — but with no daemon those suites fail rather than skip.
## Running it
Four commands, in order. The first two are once per machine.
**1. The development dependencies** — PostgreSQL and Keycloak, with the `dodossh` realm imported:
```bash
docker compose -f deploy/docker-compose.dev.yml up -d
```
**2. The schema.** The API never migrates anything: it fails readiness while a migration is pending, and
says which one. `dotnet-ef` is pinned in `.config/dotnet-tools.json`, so run `dotnet tool restore` first if
you have not:
```bash
dotnet ef database update --project src/DodoSSH.Infrastructure
```
With nothing else configured this targets the compose stack above. Set `DODOSSH_DESIGN_CONNECTION` to point
it at another database.
**3. The server:**
```bash
dotnet run --project src/DodoSSH.Api
```
It listens on `http://localhost:5233`, serving `/healthz/live`, `/healthz/ready` and — in
Development — `/openapi/v1.json`.
**4. The desktop client:**
```bash
dotnet run --project src/DodoSSH.Client.App
```
In the app, enter `http://localhost:5233` as the server. Your browser opens for sign-in — the realm ships
`alice` / `alice` — then choose a vault passphrase and **write down the recovery code**, which cannot be
skipped and cannot be recovered from the server. You can then add a host and open a shell on it. Keycloak's
admin console is at `http://localhost:18080` (`admin` / `admin`).
You can also add an SSH key, which is stored in the vault like a host and synced the same way: paste the
private key, tick **Use key** next to Connect, and the selected key authenticates instead of a password.
Three of M1's known gaps are visible immediately, so they are worth expecting rather than diagnosing:
password authentication asks for the password every time, because credentials are not a synced entity type
yet (keys are — passwords are not); a key is chosen per connection rather than remembered per host, because
binding one to a host needs a new field on the host payload and so a schema version bump; and unlock asks
for the passphrase on every launch, because no device key is registered. Host key trust also lasts one
session, because known hosts do not live in the vault yet.
### End-to-end verification
One suite runs against a real server rather than a stub. It needs a Docker daemon and nothing else, so it
is part of the ordinary test run:
```bash
dotnet test tests/DodoSSH.SystemTests
```
It brings up PostgreSQL, Keycloak and an OpenSSH server in containers, applies the committed migrations,
starts the API as a child process out of its own build output, and then drives the real client: sign in
through Keycloak, enroll, unlock, create a host, sync it, read it back on a second simulated machine,
unlock again with no network, and open a shell on the `sshd`. Roughly 25 seconds once the images are
pulled.
What makes it worth its weight is that it consumes the artefacts that ship — the realm file from
`deploy/keycloak`, the EF migrations, the API's own `appsettings` — rather than a fixture written to match
them. On its first run it found a loopback redirect URI the realm registered in a form Keycloak rejects,
and a JSON configuration gap that made the whole sync surface unreachable from the real client while every
other test passed. Both are the same class of bug: two sides of a stub agreeing with each other about
something the specification never said.
The one value it cannot take from a committed file is `Oidc:Authority`, since the container's port is
assigned at start. Everything that authority points at is still the real realm.
Development and testing are currently **Windows-only**. Anything known or suspected to differ on
Linux and macOS is tracked in [`docs/platform-flags.md`](docs/platform-flags.md), along with the
deployment gotchas that have already cost time once. Read it before assuming something works
off-Windows.
### Conventions the build enforces
- Warnings are errors. `dotnet format --verify-no-changes` gates CI.
- Package versions are centralised in `Directory.Packages.props`; `packages.lock.json` is
committed and CI restores in locked mode.
- [`BannedSymbols.txt`](BannedSymbols.txt) bans `DateTime.UtcNow` (use `TimeProvider`),
`Guid.NewGuid` (use `CreateVersion7`), sync-over-async, MD5/SHA1 and PBKDF2.
- Public members of `DodoSSH.Contracts` must be declared in `PublicAPI.Unshipped.txt`, so a
contract change is a build error rather than a client-side surprise.
## Milestones
- **M0 — foundation.** Repo structure, build conventions, CI, ADRs. *Done.*
- **M1 — vertical slice.** OIDC login → enroll → create a host → open a shell.
*Server done:* the DSH1 crypto core, the data model, sync push/pull for hosts, `/me`, and
enrollment with the identity-provider key binding.
*Client done:* the key hierarchy, the OIDC flow with the key binding, SSH connections with host key
trust, the terminal data plane, the encrypted local cache with the sync client — offline unlock, an
outbox and a field-level three-way merge, conflict matrix green — and an Avalonia shell that is
vault-backed: server URL → browser sign-in → enroll → unlock → host list → terminal. The shell's *state
machine* is covered by tests against an in-memory server, so the states that matter most (the recovery
code that cannot be skipped, the unlock that needs no network) are checked rather than remembered.
Its *layout* is not covered by anything, and that gap has already cost a shipped defect: the setup and
unlock screens were layered over the terminal's WebView, which on Windows is a native child window that
cannot be covered, so they rendered sliced with their buttons unclickable. No test in this repository
loads a `.axaml` file, and a headless one could not have caught this — there is no native window in
headless, so it would have rendered perfectly and confirmed the wrong belief. Screens get looked at, or
they are unverified.
*Verified end to end:* `tests/DodoSSH.SystemTests` drives the whole slice against a real Keycloak, a
real API, a real PostgreSQL and a real `sshd` — sign-in, the identity-provider key binding, enrollment,
offline unlock, a host through the vault to a second machine, and an interactive shell. See
[End-to-end verification](#end-to-end-verification).
Known gaps in the client, stated rather than implied by the interface: credentials are not a synced
entity type yet, so password authentication still asks for the password each time — SSH keys *are*
synced, and are the way to connect without typing anything; a key is picked per connection rather than
bound to a host, which needs a field on the host payload and therefore a schema version bump; known host
keys live in memory for one session instead of in the vault; and no device key is registered, so the
passphrase is needed on every launch until the OS keystore is wired.
- **M2 — full personal vault**, robust sync, relay.
- **M3 — teams**, sharing, ACLs.
- **M4 — hardening and ops**, packaging, self-hosting guide.
- **M5 — multi-provider OIDC**, key rotation, per-item content keys.
## Licence
[MIT](LICENSE).
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