[JC-000]

#155 phase 2, lane L3: the trust policy on UCI builds (TRUST_STORE=1). Binding inputs: phase2-spikes/DECISIONS.md (all items; item 11 governs) and l3/L3-design.md.

Merge order: #268 → #269. Rebased onto master c26e268 (#273 and #279-#286 merged).

Behaviour

Precedence. The build pin applies only when the typed host equals HTTPS_HOST (Q2). Then comes the signed bundle (advisory), then TOFU.

One resident hook. src/cert_pin.s serves as the trust hook under TRUST_STORE:

• It keeps the same SPKI-window hash and the same TLS 1.3 handshake message sequence is unenforced: a MITM completes the handshake with no Certificate at all #152 Finished interlock.
• What it compares against comes from tp_mode:
  • store: KEY CHANGED aborts, unless the operator armed exactly these 32 B;
  • first use and UNPINNED: nothing to compare;
  • build pin: the build-time pin.
• A connection that trust_pre never prepared is refused.

trust_pre runs before the dial:

• TRUST STORE EMPTY is printed on every GET while the store is empty.
• A store FAIL prints TRUST FAIL nn, then CONTINUE UNPINNED? Y/N (Q5).
  • Y gets one fetch, with the UNPINNED banner before and after. It is never recorded.
  • N gets NOT DIALLED.
• An armed accept survives only for the same host key.

trust_post runs after the close, on every exit after the dial:

• It records a first use as TOFU and an accept as ACCEPTED, only after a completed handshake.
• KEY CHANGED shows the full hash, then ACCEPT ON RETRY? A=YES. Otherwise it asks CONTINUE UNPINNED? Y/N.
• BUNDLE MISMATCH at first use: the fetch finishes, then RECORD KEY? A=YES (Q3).
• No key is read mid-handshake. Every question flushes $C6 first.

Bundle (TRUST_BUNDLE=1, off in packages).

• File: TRUST_STORE_DIR/TRUST.P.
• Checks run in order: structure, then ECDSA, then the generation floor.
• It is verified lazily once per boot and cached by digest (Q4).
• Its SHA-256 borrows tls_transcript_* before the dial.

adv-268 fixes (4414bae).

• tp_bwarn is now set explicitly (MEDIUM-HIGH: a mismatched pin byte of $00 recorded silently).
• trust_state_init runs at start.
• The stubs clear the armed accept and the mode when the cold bank refuses.
• The hook has its own segment, TRUST_HOOK_CODE.

Placement (D2 3ceabfc + adv-d2 F1 affb456)

On master plus #279-#282, the comb products overflowed LOADER (the prompts) and NET_CODE (the hook). The fix is placement only; no code changes.

• comb (cold-bank cfg):
  • TRUST_PROMPT_CODE rides the cold TRUST group: only TRUST_POLICY_CODE, which runs there, calls it.
  • The hook stays in NET_CODE.
  • The policy state (TRUST_POLICY_BSS) moves to NET_CODE.
  • The LOADER_OVERFLOW tenants (boot/vic/crypto_swap) move to CRYPTO_HOT, under TRUST_STORE only. They go through src/loader_overflow.inc, which names the segment LOADER_OVERFLOW_TS.
• TRUST_BUNDLE=1 fills the TRUST group and grows the state, so two .ifdef TRUST_BUNDLE directives switch them to TRUST_PROMPT_RES / TRUST_POLICY_BSS_RES, placed in CRYPTO_HOT.
• uci (onchip / REU): TRUST_PROMPT_CODE and _RES move from LOADER to CRYPTO_OVERLAY. LOADER_OVERFLOW_TS sits beside LOADER_OVERFLOW in NET_CODE.
• COLD_BANK=0 + TRUST_STORE=1 is still an $(error).

Byte identity (master c26e268 + this + #269 8fdebe7; every hash below re-measured there, identical to the pre-rebase trial 113415a)

• Every image without the trust store is byte-identical to the same stack without this PR:

  image	PRG
  uci	0046561b
  uci-onchip	1061e8ff
  uci-comb	26e032dd
  comb demo	0f949c33
  comb demo + HTTPS_PIN_SPKI	5835f7c2
  ip65	0a0b7a78
  ip65-onchip	78a10748
  uci-m3	links

• adv-d2 F1: D2 alone had moved LOADER_OVERFLOW for every comb image and broke the demo + pin build (HOT -56). affb456 restores it.

Margins (tools/measure_margins.py, free bytes, on c26e268 + #268 + #269)

image	PRG	LOADER	NET_CODE	OVERLAY	HOT
ship uci-onchip TS (TRUST_RELEASE=1)	da4d607e	588	184	333	166
ship uci-comb TS (TRUST_RELEASE=1)	e6750100	78	38	47	1,237
comb Wikipedia demo TS	59bbc7bd	21	38	29	48
onchip + bundle	0c76f1d1	31	184	210	32
comb + bundle	9e46fd9a	67	53	47	990
onchip + bundle + pin	8cafb05d	31	184	14	32
uci TS	58f2214b	588	176	430	122

• Rig builds (rig_trust_policy local/live, test_rig_scratch demo-trust, rig_trust_store) all link.
• Known and not shipped: comb + TS + pin does not link (it did not before D2 either), and a 63-char host on comb + TS is 1 B over.

Red-green

• tools/test_trust_policy_6502.py runs the shipped do_https_get on the 6502 interpreter, with a real Python ECDSA check of the struct the C64 built. Default five images: 432/432.
  • Since adv-d2 F2 (a0f53fa), a simulated handshake fills all 2048 B of cert_buf, as a real flight does. A resident call into the cold prompt now runs $02.
• tools/mutate_trust_policy.py: 22/22 killed. That includes the new "resident stub calls into the cold TRUST group" mutant, which survived before a0f53fa.
• tools/test_typed_target.py on TRUST_STORE images (adv-d2 F3, d1bb592). The suite answers CONTINUE UNPINNED? when it appears: Y for accepted targets, and refused targets must never be asked. One case answers N and expects NOT DIALLED.
  • Before: the suite hung on every TRUST_STORE image.
  • Now: onchip + TS 163/163, comb + TS 164/164; non-TS 138/138 and 139/139.
  • adv-d2's three mutants of the new path all go red.
• tools/test_trust_bundle_policy_c64.py (VICE, real 6502 SHA/ECDSA): good, cached, flipped record, wrong key and replay, 5/5.
• Other suites on the trial: test_cold_bank 118/118 (its cfg mirror includes the D2 edits), test_trust_store_6502 128/128 on onchip and comb, test_reu_body_sink 76/76, test_quit_basic_exit comb + TS 68/68.
• Comb with LOADER_OVERFLOW_TS in HOT: test_ecdsa_kat_oracle comb + TS 6/6.
• Root pytest: 433 passed and 1 failed. The failure is test_ip65_hw_checks_unit, which needs an ip65 build: build state only.

Hardware

U64E, fw 3.15 3a1ff9ff, FPGA 126, core 1.50, 48 MHz. Each run went through DeviceLock, then prepare_device and preflight_reu, using tools/uci/rig_trust_policy.py in /USB1/c64https-test. The PRGs were built on 8fdebe7, whose image bytes equal this branch's.

run	PRG sha256	result
local, comb TS (TRUST_STORE_DIR=/USB1/c64https-test HTTPS_PORT=4433)	d825488203f54d79…	PASS 28/28
local, onchip TS (same flags)	356f2b13589bd829…	PASS 28/28
live, comb Wikipedia demo TS: en.wikipedia.org first use	1baa43a96bd5f681…	PASS 4/4: TOFU C0A0573A… recorded

The live run's first attempt (same PRG) was 1/4. The rig's 240 s fetch budget expired mid-body. 011209b makes live mode wait 900 s, and the 4/4 run above used that.

Deviations

• COLD_BANK=0 + TRUST_STORE=1 is refused at build time.
• The bundle-corroborated record flag is not set.
• A store FAIL skips the bundle for that fetch.

🤖 Generated with Claude Code