Second pass over src/aacs and src/css. No production change; the only
non-test edits are two fixture bytes and one test rename.
Five latent panics on untrusted data, every guard correct and none
tested — so each was free to be deleted:
variant.rs:224 a 0x04 record not a multiple of 5 indexes p_uv[0..4]
off a one-byte tail
variant.rs:269 a 0x0c record shorter than the 0x04 slot count
slices past the cvalue table
stevenson.rs:177 short sector read -> index 138 into a 129-byte slice
stevenson.rs:208 a crib longer than the 1920-byte encrypted region
-> index 2058 into 2048
stevenson.rs:272 a header periodic all the way to offset 0 ->
subtract with overflow
That last one is reachable from ORDINARY DVD data — constant or padding
bytes are periodic. Verified on HEAD: widening the guard to <= 0x80
passes all 64 css tests unmutated.
media_key_variant_from_kp had only a soft-correction test, so every
step past that early return was unexecuted. The new two-slot fixture
puts the covering slot at index 1, so the uvs[1 + 5*idx] and
cvalues[idx*16] strides stop multiplying by zero.
derive.rs:319 + -> - confirmed killable, as the first pass predicted:
p == 0 makes (p-1)..32 underflow. Every prior fixture used a uv whose
lowest set bit was 4, 10 or 11, so trailing_zeros() was never 0.
One fixture bug caught and fixed rather than papered over: a |= mutant
first SURVIVED because mk[14]'s 0x04 bit happened to be set, making OR
and XOR agree. The byte is now clear and an assert_eq! pins it, so the
fixture cannot drift back into agreeing with the mutation it exists to
catch.
walk_mkb_be24_high_byte_is_honored renamed to
walk_mkb_be24_middle_byte_is_honored. Its 0x00_0110 length exercises
the << 8 term only, which is why << 16 -> >> 16 survived it. The name
was the lie; both framings are worth having, and the comment now points
at the genuine high-byte test at 0x01_0004.
derive.rs 146:32 and 154:30 stay untested, now with a proof rather than
a judgement: bit_pos == -1 requires current_v_mask == 0xFFFF_FFFF, and
calc_v_mask can never return that — its loop condition holds at
!v_mask == 0, so it always shifts at least once. Both branches are
reachable only after the walk has gone non-convergent and is heading
for the bounded exit, where the return value is undefined. Termination
is already pinned.
Equivalents proven by observing green, including six more OR/XOR pairs
on provably disjoint bit fields, and the two KEY_CORRECTION_DATA sites
where the constant is the documented all-zero placeholder so x ^ 0 ==
x | 0. Those become killable only if a real per-licensee KCD is wired
in.
A partial confirmation sweep (138 of 415 mutants before the box
saturated) found 135 caught, one timeout that is itself a detection,
and exactly one survivor — the KEY_CORRECTION_DATA equivalent above.
163 of 322 surviving mutants across src/aacs and src/css. No production
line changed — every function read correct; the finding was always an
absent test.
Two structural holes, both verified against HEAD before landing.
variant.rs had no test that ever produced a Media Key. Every terminal
assertion in the module was an Err classification — NotVariantMkb,
SoftCorrectionRequired, OnlineChallengeRequired. So the entire 2.1
success path (VARIANTS lookup, VKD selection, Kpnew, the final unwrap,
the verify gate) was pinned by nothing, and that path produces the
Media Key that becomes the VUK that decrypts every byte of a 2.1 disc.
Built the first complete planted variant MKB: the VARIANTS entry is
chosen as Kvn ^ 1 so the real VKD sits behind a decoy at table index 1,
making the lookup load-bearing rather than incidentally correct. That
one fixture kills 23 operator mutants across three functions.
aesg3 — the subset-difference tree node function — was in the survivor
list as replaceable by [0; 16], meaning every device key in the crate
would derive the same Processing Key. It is caught today only as a side
effect of a negative test added after the mutation run; nothing asserted
the relation itself. Pinned now via the spec relation ([C] 3.2.2) using
the FORWARD primitive, with s0 transcribed independently rather than
read back from AESG3_SEED, so the test cannot agree with a mutated
constant.
Same shape in derive.rs: plant_mkb was one slot with zero descent, so
slot indexing was the identity permutation and the ancestor-descent
branch never ran — which is why 39 of recover_dk_position's mutants
survived. Added a 3-slot fixture keyed at index 2 and a four-level
descent fixture whose expected Processing Key is written out as an
explicit aesg3 chain rather than computed by calc_pk_from_dk; a fixture
built by the function under test moves with its own mutations.
Two latent panics on untrusted input now have tests: a 0x05 cvalue
table shorter than the 0x04 slot index, and a drive declaring more
payload than the 32772-byte response buffer holds.
23 equivalents claimed with reasoning, and confirmed empirically where
possible — all eight css/lfsr mutants were run and exactly the seven
disjoint-bit-lane ones survived.
Explicitly NOT claimed equivalent: derive.rs 146:32 and 154:30 are
reachable, but only on the non-convergent bounded-exit path where the
function's sole contract is termination. A test there would pin
defined-but-meaningless output.
Noted for the next pass: the pre-existing walk_mkb_be24_high_byte_is_honored
used total length 0x0110, whose high byte is zero — it exercised the
middle byte only, which is why << 16 -> >> 16 survived it. Left in
place; a real one was added at 0x01_0004.
AacsState (public via Disc.aacs) and Key (the decrypt_with key-transport enum)
are crate-root re-exported and carried VUK/unit/read-data keys + volume id on
#[derive(Debug)]; HandshakeResult carried the VID + AACS 2.0 bus key. Manual
Debug impls print shape only, guarded by red->green tests.
These carry raw unit-key / VUK / processing-key bytes on their Debug; manual impls
print shape only (unit_keys_len, redacted markers). Each has a red→green test.
Round-7 findings from the 10-phase release audit (no HIGH; convergence):
- Cap DtsParser.pts_marks (MAX_PTS_MARKS): a run of zero-length timed PES
packets grew no buffer bytes, so the drain_front mark-prune never ran —
the deque could accumulate without bound on hostile PS input.
- detect_disc_format tested HVDVD_TS before BDMV while the title-scan
dispatch tests BDMV first, so a disc with both trees would be classified
HD-DVD but enumerated as Blu-ray. Align both to BDMV → HVDVD_TS →
VIDEO_TS.
- Document why the DTS new-PES re-base can emit a locally-decreasing PTS
(the muxer's block_ts applies the strictly-monotonic audio nudge, tested
in mkv.rs) — this is by design, not a mux defect.
- Fix stale aacs/keys.rs comment references (functions moved to
aacs/inf.rs / aacs::resolve/derive in the module split).
Round-2 findings from the 10-phase release audit:
- parse_vti_clip_order bucketed hits by residue with an O(stride*hits)
rescan and no hit cap, so a crafted HD-DVD VTI packed with millions of
`.EVO` tokens (up to the 64 MiB UDF read cap) could burn seconds of CPU
on a routine scan. Bucket in a single O(hits) pass and cap collected
hits at MAX_VTI_HITS (a real table holds a few dozen).
- Fix the stale `super::keys::…` intra-doc links left by the aacs module
rename: the referenced fns live in `super::derive`.
Round-1 findings from the 10-phase release audit:
- SparsePtsReorder buffered its current GOP with no bound, draining only on
a keyframe — an open-GOP or crafted program stream that never signals one
could hold the whole title in RAM. Force-complete the GOP at
MAX_GOP_FRAMES, matching the MPEG-2 parser's backstop.
- inject_unit_keys labelled a 2.1 FMTS disc as AACS 1.0 / bus-encryption
off; FMTS is UHD-family, so synthesize the UHD version + bus encryption.
- The compiled Key Correction Data was a non-zero 16-byte constant fed into
the Media Key derivation. Per the no-compiled-keys rule it is now all-zero;
the chain still cannot complete on a real disc (documented), so this is
behaviour-neutral — all variant tests pass unchanged.
- Fix stale doc references (broken `super::variants` intra-doc links, and
`aacs::keys` comments) left by the module rename.
Correct the variant Media Key chain against two real variant MKBs
(Zombieland v70, Stand By Me v70): C for Kmp is the per-slot block of
the 0x0c cvalue table indexed by the matched subset-difference, not the
0x2d head. The 0x2d record is the VARIANTS table (leading body-16 bytes,
one big-endian u16 per subset-difference) followed by a trailing 16-byte
Nonce, with no leading header. VKD stays at 0x2f.
Route record-type selection through the named REC_* consts in mkb rather
than bare hex, and document that Key Correction Data is per-licensee: no
universal constant exists and none is compiled in, so on a real disc the
chain yields a wrong Media Key that the Verify-Media-Key gate rejects
rather than emitting a bad key. This is a key-acquisition gap, not a
code gap.
- aacs/resolve: a media-keys-only provider missing the VID classifies as
VidUnavailable, not NoMaterial (an MK derives the VUK once the VID
arrives).
- disc/bluray: mark a clip seen only after its .clpi parses, so a
transient parse failure on the first PlayItem cannot suppress the
clip's extents for a later PlayItem referencing it that succeeds.
- disc/patch: log rather than swallow mapfile record/flush failures on a
reverify downgrade, so a failed persist cannot silently mismark a bad
unit good on resume.
- mux/ts: flag a discontinuity when a partial PES is dropped, matching
the other partial-drop paths.
- mux/demux_thread: the no-demuxer branch forwards an empty batch for
early consumer-disconnect detection instead of reading the whole disc.
- io/pipeline: correct the send-timing log (as_secs_f64, not as_micros
printed as ms).
- aacs/derive, aacs/variant, disc/read_error, keysource: comment/doc
accuracy. sector/prefetched, udf: remove dead fields/functions.
- mux/disc: assert unit-aligned read counts in the test.
Redesign derive_media_key_variant to the minimal derivation surface:
derive_media_key_variant(mkb_records, pk) -> Km
- PK-input only. Deriving Kp from device keys (DK -> PK) is a separate
concern (walk_processing_key); a leaked 2.1 key is a PK, and the chain
starts at Kp. A bare PK arrives without its subset-difference slot, so
the primitive tries it against every slot and returns the Km for the
slot that passes the MKB's Verify-Media-Key record -- mirroring the
classical bare-PK derive_media_key_from_pk, gated by the chain's own
verify so an unverified key is never returned.
- VID-free: the Media Key is MKB-scoped. VUK stays the separate
derive_vuk(Km, VID) step.
- KCD is a fixed algorithm constant compiled in, not a caller parameter
(removes the kcd argument, the placeholder const, and KcdNotProvided).
- Soft-correction / online-challenge slots are treated as non-covering;
surfaced over the generic miss so a disc needing those modes is
distinguishable from a non-covering key.
resolve_keys_v21 updated to walk DK -> PK first, then call the primitive
and derive the VUK from Km + VID. Module + helper docs refreshed to the
pinned record layout; tests reworked for the PK-only signature.
variants_for_uv previously returned None (placeholder), dead-stopping the
Media Key Variant chain at VariantsTableUnavailable on any real disc. Layout
now pinned against two real 2.1 variant MKBs (Zombieland v70, Stand By Me v70):
the 0x2d Encrypted-Media-Key-Variant-Data body is sd_count u16 VARIANTS entries
(1:1 with 0x0c cvalues / 0x04 subset-diffs) followed by the 16-byte per-disc
Nonce at the tail. variants_for_uv reads the sd_slot_index-th u16.
With this the chain runs fully: Kmp -> Kpnew(=Kmp^KCD, extracted CyberLink
constant) -> VKD(0x2f) -> Km -> Kvu. The only remaining input is a covering
2.1 Processing Key to validate against a known answer; until then the final
Verify-Media-Key (0x86) gate rejects any wrong layout pick, so a bad key can
never be emitted. Tests updated to reflect the wired lookup; 1.86 precommit
green (fmt+clippy+tests).
The volume_key module was only 34 lines and is just the tail of the same
DK/PK -> MK -> VUK -> UK derivation ladder as media_key. Fold both into one
derive module so every aacs module is a substantial, distinct responsibility
(crypto/mkb/derive/inf/content/variant/resolve). Relocation only; logic hash
identical (95fb9924); 2210 tests green.
Break the 2800-line keys.rs into four responsibility-scoped modules:
- media_key.rs: DK/PK -> Media Key subset-difference walk (+ probe harness)
- volume_key.rs: VUK derivation, unit-key unwrap
- inf.rs: Unit_Key_RO.inf parsing, disc_hash, content cert, in-drive MKB read
- resolve.rs: the resolve_keys_* orchestration (keys.rs renamed)
Relocation only; the (white-box) test suite stays in resolve.rs and pulls
the moved items via glob imports. Proven byte-identical to the pre-refactor
state via the logic hash (95fb9924); 2210 tests green.
Relocate the shared MKB machinery into a single mkb module: the record
framing walker + MkbRecord view (from variant), the MkbType/AacsVersion
classification, the MKB-file utilities, and the record-body finders (from
keys). Fixes the inversion where the MKB parser lived in the 2.1-only
variant module. variant.rs keeps its local MkbRecord-based mkb_find_mk_dv
(name collision with the raw one; unified in the dedup follow-up).
Relocation only. Proven byte-identical to the pre-refactor state via the
function-body logic hash (imports normalized out); 2210 tests green.
Relocate the shared low-level primitives into a single crypto module:
aes_ecb_encrypt/decrypt, aes_cbc_decrypt, aes_g (from content/variant) and
aesg3 + AESG3_SEED (from keys), plus AACS_IV. Fixes the scatter where AES-G
lived in the 2.1 file and AES-G3 in keys. Relocation only — no rename, no
logic change (logic-hash identical to baseline; 277 items; 2210 tests green).
Pure file+module-path rename. 'content' names the AACS unit-decrypt layer
(distinct from the top-level sector-decrypt driver crate::decrypt), and
'variant' (singular, spec term 'Media Key Variant') names the 2.1 chain.
Logic-hash identical to baseline; 277 items intact; tests green.
Matthew Jackson