jaap-jan 3829217e8a Add sync engine: cursors, push/pull, and the advisory-lock ordering proof (M1)
The vault write path. Push is the only way items change — no per-entity POST/PUT/DELETE —
so one place enforces revisions, the change log and access control.

The concurrency hazard, now proven rather than asserted:
bigserial assigns sequence values when the INSERT runs, not at commit, so transaction A
can take sequence 5 while B takes 6 and commits first. A reader polling in between sees
only 6, advances past 5, and never learns about it. AdvisoryLockOrderingTests reproduces
that gap WITHOUT the lock first — otherwise the with-lock test proves nothing, since it
would pass just as happily if the interleaving never occurred — then shows
pg_advisory_xact_lock removes it, and that 12 concurrent writers produce no gaps.

Cursors are opaque and HMAC-tagged, and carry their vault id. 29 unit tests cover the
rejections, which are the point: an accepted-but-wrong cursor is silent data loss, strictly
worse than an error a client can resync from. Rejected: tampered tag, tampered payload,
foreign signing key, a legitimately-issued cursor from another vault, truncation, and
hostile input (never throws — cursors come from clients).

Push semantics:
- 200 even on partial failure, with per-operation status, so one stale item cannot block
  everything a client queued while offline.
- Conflict returns the server's current row for client-side three-way merge. The server
  cannot merge ciphertext, so never last-writer-wins.
- opId receipts make retries exactly-once per operation, not per batch — a client retrying
  a partially-overlapping batch after a timeout would otherwise double-apply what landed.
- A tombstone beats a late upsert, and delete clears hostname/port: leaving the address
  would keep the server able to resolve a host the user believes they deleted.
- Relay field validation mirrors the DB CHECK so a bad request is a clear Invalid rather
  than a constraint violation surfacing as a 500.

Authorization goes through IVaultAccessService, which returns the same answer for "absent"
and "forbidden" — distinguishing them is an existence oracle for other tenants' vault ids.
Team vaults are explicitly denied until M3 rather than falling through to a permissive
default. JIT provisioning keys on (issuer, subject), never email, and handles the
concurrent-first-request race via the unique index.

Renamed two domain types: Host -> SshHost, because Host collides with
Microsoft.Extensions.Hosting.Host in every file of a web project, and SyncChange ->
VaultChange to stop it colliding with the Contracts DTO of the same name. Aliasing at every
use site would have been permanent friction.

Worth noting: `ef migrations has-pending-model-changes` reported clean after those renames
even though the snapshot still said "DodoSSH.Domain.Host" — it diffs tables, not CLR type
names. The snapshot was regenerated and the emitted DDL diffed against the previous
artifacts/schema/v0.1.sql to confirm the rename produced no schema change.

Also removed ConfigureAwait(false) from test methods: xUnit1030 flags it as bypassing
parallelization limits, which is why MA0004 is suppressed in test projects.

Verified: 0 warnings on a clean rebuild, 146 tests pass (up from 122), format clean.

Endpoint-level tests are the immediate next step: they need a WireMock OIDC/JWKS stub and
real JWT minting, so the "wrong user is denied" matrix does not exist yet for these two
routes. The service-layer authorization and the concurrency property are covered.
2026-07-28 15:02:02 +02:00
2026-07-28 12:28:44 +02:00

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 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

Two 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.

The reasoning behind each major decision is recorded in docs/adr/, starting with the E2EE trust model.

Repository layout

src/
  DodoSSH.Contracts       DTOs shared with the client — the real API contract
  DodoSSH.Crypto          DSH1 envelope, AAD derivation, key wrapping
  DodoSSH.Domain          entities and invariants, no EF
  DodoSSH.Infrastructure  DbContext, configurations, migrations
  DodoSSH.Api             the host
tests/                    one test project per source project
docs/adr/                 architecture decision records

Building

Requires the .NET SDK pinned in global.json (10.0.x).

dotnet build DodoSSH.slnx
dotnet test DodoSSH.slnx

Run the API locally:

dotnet run --project src/DodoSSH.Api

It listens on http://localhost:5233, serving /healthz/live, /healthz/ready and — in Development — /openapi/v1.json.

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 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. Gated on freezing DodoSSH.Contracts and the crypto AAD, plus two client spikes (Linux WebView, SSH.NET window-change).
  • 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

Not yet chosen.

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