* fix(hardware): constant-time HMAC sync-beacon tag compare (ADR-157 §B4)
AuthenticatedBeacon::verify compared the 8-byte HMAC-SHA256 tag with
`self.hmac_tag == expected`, which short-circuits on the first differing
byte and leaks, via verification latency, how many leading bytes a forged
tag matched — a byte-by-byte tag-recovery oracle (~256·N trials vs 256^N).
Replace with a hand-rolled branch-free `constant_time_tag_eq`: XOR-accumulate
every byte difference into a single u8 with no early exit, compare to zero
once. `#[inline(never)]` + `core::hint::black_box(diff)` resist the optimizer
reintroducing a short-circuit or a non-constant-time memcmp; length mismatch
returns false without inspecting contents. No new dependency — ADR-157 had
deferred this only to avoid the `subtle` crate; a fixed 8-byte compare needs
none.
Test (hard gate): tag_compare_is_constant_time_shape — equal / first-differ /
last-differ / all-differ / length-mismatch + end-to-end verify() last-byte
tamper. Proven to fail on a last-byte-skipping constant-time bug. A coarse
timing smoke check (tag_compare_timing_invariance_smoke) is #[ignore]d to
avoid CI flakiness. Grade MEASURED (constant-time construction).
ADR-157 §8 §B4 → RESOLVED. wifi-densepose-hardware: 164 passed / 0 failed.
Co-Authored-By: claude-flow <ruv@ruv.net>
* feat(wifiscan): MEASURE native wlanapi.dll vs netsh throughput (ADR-157 §5 #4)
ADR-157 §5 #4 recorded the native wlanapi.dll multi-BSSID fast path as
"asserted but NOT implemented; live scanner is the ~2 Hz netsh shim". Audit
finding: that status is stale — wlanapi_native::scan_native already implements
the real WlanOpenHandle → WlanEnumInterfaces → WlanGetNetworkBssList →
WlanFreeMemory/WlanCloseHandle FFI (handle cleanup on all exits, length-bounded
buffer walks, #[cfg(windows)] with typed Unsupported off-Windows), and
WlanApiScanner::scan_instrumented already wires it native-first with a netsh
fallback. The missing piece was an honest MEASUREMENT.
Add benchmark_backend(backend, window): drives one specific backend over a
fixed wall-clock window so netsh is timed independently (the existing
benchmark() picks native-first and so never measures netsh on a box where
native works). Returns None for an unavailable native path (honest negative,
not a fabricated number).
MEASURED on this box (Intel Wi-Fi 7 BE201 320MHz, 2026-06-13), 10 s window:
native 21.42 Hz vs netsh 3.84 Hz = 5.57× (mean 5.0 BSSIDs/scan each).
native-only run: 18.0 Hz. 50/50 back-to-back native scans, no handle leak.
A real positive result — NOT a fabricated 10×. Achieved 21.4 Hz is in the
asserted >2 Hz regime, below the asserted 10–20 Hz upper bound.
Tests (live-WLAN, #[ignore] for CI, RUN here):
measure_native_vs_netsh_throughput, native_scans_dont_leak_handles,
measure_native_scan_rate. Non-ignored pin native_scan_runs_real_ffi_on_windows
(pre-existing) stays green. wifi-densepose-wifiscan: 94 passed / 0 failed.
ADR-157 §5 #4 + §8 → MEASURED (was ACCEPTED-FUTURE / CLAIMED-unmeasured).
Co-Authored-By: claude-flow <ruv@ruv.net>
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