Rob 073203abae Resolve issue #6 — LRRTT and HEADER_1 for link-addressed DATA (§6.4.2, §6.4.3)

Upstream RNS enforces two requirements in code that SPEC.md left implicit;
both caused silent message loss in a clean-room Go LXMF service against
upstream Python rns 1.2.4 / lxmf 0.9.7.

§6.4.2 LRRTT — initiator's link-activation packet
  - HEADER_1, DATA, dest_type=LINK (0x03), ctx=0xfe; body is
    `umsgpack.packb(rtt_seconds)` encrypted with the link's session keys.
  - The responder transitions HANDSHAKE→ACTIVE only on LRRTT receipt
    (Link.py:534-553), which is also what fires the link_established
    callback. LXMF's set_resource_strategy(ACCEPT_APP) is installed
    from that callback; without it, every RESOURCE_ADV the initiator
    sends hits the silent ACCEPT_NONE branch at Link.py:1087.

§6.4.3 Header type for post-handshake DATA and Resource
  - Link-addressed packets are routed via link_table, which forwards
    header bytes verbatim (Transport.py:1587-1622). HEADER_2 with a
    relay's transport_id therefore arrives at the destination intact
    and is dropped by packet_filter (Transport.py:1283-1285) as
    "for another transport instance".
  - Mandates HEADER_1 with no transport_id for all post-handshake
    link DATA / Resource / control packets regardless of hop count.
  - Asymmetry with LINKREQUEST (which IS path_table-routed and so
    HEADER_2-eligible) is spelled out.

Companion changes:
  - §6.4 renamed to "Session keys and link activation"; existing
    HKDF content moved into §6.4.1.
  - §2.5 LRRTT context-byte entry points at §6.4.2.
  - §12.5.2 (Link DATA forwarding) cross-references §6.4.3.
  - §14 failure-modes table: two new entries for the silent-drop
    chains documented above.
  - flows/send-link-lxmf.md step 4 strengthened (LRRTT is mandatory,
    not informational); step 6 corrected (Transport.outbound does NOT
    apply HEADER_1→HEADER_2 for link DATA — that conversion is
    path_table-keyed, link DATA is link_table-keyed).
  - test-vectors/links.json extended with an LRRTT entry: pinned
    rtt_seconds=0.05 + pinned 16-byte IV produces deterministic
    wire bytes for the encrypted body.
  - tools/regen_links.py drives the LRRTT generation with an
    os.urandom patch for the Token IV.
  - tools/verify_link_lrrtt.py (new) locks the wire claims:
    HEADER_1, ctx=0xfe, dest=link_id, body decrypts under
    derived_key to msgpack float64 matching rtt_seconds.

Citations all verified against installed RNS 1.2.4 / LXMF 0.9.7.
All 14 verifiers PASS.

2026-05-10 14:35:56 -04:00

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Verifier scripts

Self-contained Python scripts that test claims in ../SPEC.md against the upstream RNS / LXMF Python stack.

Conventions

Each script verifies one claim or one related cluster of claims.
Exit code 0 on PASS, non-zero on FAIL.
Print a one-line PASS/FAIL summary plus a unified diff or hex dump on mismatch.
Reference the SPEC.md section the script verifies in a docstring at the top.

Required environment

pip install rns lxmf

The scripts read RNS.__version__ at startup and print it in their output so a future reader can tell which RNS version a verification ran against.

Status

Populated against RNS 1.2.4 / LXMF 0.9.7:

Script	Verifies SPEC.md section	Status
`verify_destination_hash.py`	§1.1, §1.2, §1.3 — identity composition, `dest_hash = SHA256(name_hash \|\| identity_hash)[:16]`, on-disk private-key round-trip via `to_file`/`from_file`	✅
`verify_packet_header.py`	§2.1, §2.2, §2.3 — flag byte layout, HEADER_1/HEADER_2 form, originator HEADER_1→HEADER_2 conversion via upstream `Transport.outbound`	✅
`verify_token_crypto.py`	§3 — Token encrypt/decrypt, HKDF salt = identity_hash, HMAC-then-AES order, PKCS#7 padding	✅
`verify_announce_app_data.py`	§4.3 — LXMF announce app_data 2-element form, parser tolerance	✅
`verify_announce_roundtrip.py`	§4.1, §4.2, §4.5 — announce body layout, signature, dest_hash recompute, tamper rejection	✅
`verify_lxmf_opportunistic.py`	§5.1, §5.2, §5.5, §5.6 — full identity → encrypt → decrypt → parse round-trip	✅
`verify_proof_packet.py`	§6.5 — implicit (64B) and explicit (96B) proof body forms, validator length-dispatch	✅
`verify_link_handshake.py`	§6.1, §6.2, §6.3, §6.6 — LINKREQUEST/LRPROOF body order, link_id derivation, signalling	✅
`verify_link_lrrtt.py`	§6.4.2, §6.4.3 — LRRTT wire form, HEADER_1 header, dest_type=LINK, ctx=0xfe, link-form Token body, msgpack float64 plaintext	✅
`verify_path_request.py`	§1.2 well-known hashes, §7.1 LXMF path-preamble gating	✅
`verify_rnode_split.py`	§8.3 — RNode air-frame split-packet TX/RX state machines	✅
`verify_msgpack_quirk.py`	§9.3 — encoding name as bytes vs str affects upstream parsing	✅
`verify_stamps.py`	§5.7 — workblock determinism, PoW stamp search/validate, ticket shortcut	✅
`verify_ratchet_dedup.py`	§7.3 / §4.5 step 6.3 — confirms replay defence is keyed on `random_blob`, NOT on `(dest_hash, ratchet_pub)`	✅
`regen_identities.py`	regenerates `test-vectors/identities.json`	✅
`regen_announces.py`	regenerates `test-vectors/announces.json` (deterministic announce wire bytes, with and without ratchet)	✅
`regen_lxmf.py`	regenerates `test-vectors/lxmf.json` (deterministic opportunistic-LXMF plaintext + Token ciphertext)	✅
`regen_links.py`	regenerates `test-vectors/links.json` (deterministic LINKREQUEST + LRPROOF + derived session key)	✅

See ../agent.md §5 and ../todo.md for the remaining priority order.

3.1 KiB Raw Blame History

Verifier scripts

Conventions

Required environment

Status

3.1 KiB

Raw Blame History