Files
mxaccess/design
Joseph Doherty ce27b63010 [M5] auth: deterministic HMAC fixture test rules out crypto stack
Adds end-to-end byte-equality test against a `.NET reference fixture
captured via the new `MxAsbClient.Probe --dump-deterministic-hmac`
flag. All inputs are pinned (passphrase, prime, generator, private-
key bytes, remote-pub bytes, message number, connection ID, AES IV,
consumer-data + IV bytes), so the test reproduces .NET's exact
output for every crypto step:

1. shared = remote_pub^private_key mod prime —  matches
2. crypto_key = shared || passphrase_utf8 —  matches
3. hmac = HMAC-SHA1(crypto_key, xml_utf8) —  matches
4. aes_key = PBKDF2-SHA1(base64(crypto_key), salt, 1000, 16) — 
5. encrypted_mac = AES-CBC(aes_key, iv=zeros, hmac, PKCS7) — 

This conclusively rules out the entire crypto stack as the source of
the live AuthenticateMe `dispatcher/fault`. Our DH math, HMAC engine,
PBKDF2 derivation, AES-CBC PKCS7, and crypto_key concatenation are
byte-equal to .NET. The remaining live failure must come from one
of: (a) wire-level ConnectionValidator NBFX shape (DataContract field
names, mustUnderstand attribute, namespace), (b) WCF binary message
header (action+to dict pre-pop), or (c) a subtle XmlSerializer quirk
for live values that the hardcoded fixtures don't exercise (Guid
format edge case, base64 line wrapping, ulong text rendering).

Fixture lives at `crates/mxaccess-asb-nettcp/tests/fixtures/
deterministic-hmac/authenticate-me.kv` (KV format, ASCII hex, lines
trim CRLF/LF transparently). The companion `README.md` documents the
capture procedure and the per-step decomposition. The test consumes
the .NET-supplied canonical XML directly from the fixture's
`xml_utf8_b64` so a Rust XML emitter bug would not mask a Rust
crypto bug — XML byte-equality is verified separately by
`mxaccess-asb::xml_canonical::tests` against the `signed-xml/*.xml`
fixtures.

Workspace: 710 unit tests pass (was 709 + 1 new). Clippy clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-05 19:12:17 -04:00
..

design/ — Rust port architectural plan

This folder is the design contract for the Rust replacement of AVEVA/Wonderware MXAccess. It is the gap between the .NET reference in src/ and the Rust crates that will be written under a sibling rust/ workspace (per CLAUDE.md).

The folder is structured as a small set of focused documents. Read in order; each builds on the previous.

File Purpose
00-overview.md Mission, two-layer goal, architectural principles, non-goals
10-raw-layer.md Byte-accurate raw MXAccess layer (codec + transport + session)
20-async-layer.md Idiomatic Tokio async layer on top of the raw layer
30-crate-topology.md Cargo workspace, crates, dependencies, build/test commands
40-protocol-invariants.md Bill of materials: IIDs, opnums, envelope/handle bytes
50-error-model.md MxStatus, error types, panic/cancellation policy
60-roadmap.md Milestones M0..M6, validation strategy
70-risks-and-open-questions.md Parity gaps, unproven flows, cross-platform constraints
dependencies.md Cross- and within-milestone parallelism map; agent budget per phase
review.md Adversarial review log (BLOCKER/MAJOR/MINOR/NIT findings, all resolved)
prompt.md /loop driver prompt for autonomous M2M6 execution
followups.md Open / resolved deferred work items; auto-triaged by prompt.md Step 0 (created on first /loop run if missing)

The design is grounded in the .NET reference at src/ and the protocol artifacts in docs/, analysis/, and captures/. Do not introduce protocol behavior in these documents that is not already proven in the reference. When adding a new claim about wire format, cite either:

  • a .cs file path in src/MxNativeCodec/, src/MxNativeClient/, or src/MxAsbClient/, or
  • a docs/*.md spec file, or
  • a captures/0NN-frida-* directory or analysis/frida/*.tsv row.

This folder is documentation, not code. When the Rust workspace is created, the design here is the contract it must satisfy. When evidence in captures/ invalidates a design decision here, update the design first, then the code.

Reading order

  • New contributor: 00 → 30 → 10 → 40 → 20 → 50 → 60 → 70.
  • Protocol question: 40 first, then the relevant section of 10.
  • API question: 20 first, then 50.
  • Planning a milestone: 60 first, cross-reference 70 for blockers.
  • Scheduling concurrent work: dependencies.md for the per-phase parallelism map.
  • Driving M2M6 autonomously via /loop: prompt.md (and the followups.md triage log it maintains).