Replace the AACS-specific inline key-fetch in the decrypt decorator with
a scheme-neutral recovery seam: the input stream (L3) installs a Recover
closure (none / AACS key-fetch) and the decorator (L2) runs it at the
single decrypt-miss point. FMTS (AACS 2.1) forensic-segment units that no
key opens are just undecryptable units, concealed and counted as ordinary
decrypt loss with no FMTS-specific branch ("a loss is a loss"), so the
separate bytes_undecryptable bucket collapses into one loss count.
- sector/recovery.rs: the seam (MissOutcome, none/key_fetch factories),
naming no encryption scheme in its type.
- FMTS: segment routing primitives + BYPASS_FMTS_KEY, and an upfront
ensure_forensic_segments_decryptable gate (Error::FmtsKeyMissing) in
the mux input path, parallel to the unit-key gate.
- CSS descramble/rekey moves from decrypt_sectors into
css::descramble_region: CSS self-recovers from the data itself, so it
stays OFF the seam (which is only for external inputs).
- disc/mod.rs also: main-title selection aligned to largest physical
size; is_regular read from the open file handle, not metadata(path),
fixing a swallowed sync_all on a fresh-rip ISO. decrypt_threads()
resolved once via OnceLock off the per-buffer hot path.
Post-read verify gate (new src/disc/verify.rs): UnitVerifier buffers/aligns the disc-absolute read stream into clip-file 6144-byte units, then makes one decryptability() decision per unit (CPI gate -> held keys -> key_fetch -> strict TS). POST_READ_VERIFY const kill-switch; fail-safe contract (only ever downgrades units it is confident are undecryptable; every doubt skips). Hooked into Disc::sweep (producer observes ciphertext -> WorkItem::MarkBad after the Good, FIFO-ordered) and Disc::patch (post-loop reverify_iso reads recovered units whole from the patched ISO). extract::clip_layouts enumerates AACS clips for the gate.
Standards-correct AACS verify: aacs::unit_is_clean_ts is a strict port of libaacs _verify_ts (all 32 TS syncs, not a majority vote); decrypt_unit accepts a key only on it; the majority verify_ts is removed. Deleted the Disc::verify_clips post-pass bolt-on (its primitive is absorbed by the read-path gate).
libaacs/DVD audit fixes: content-cert bus_encryption flag now read from bit 7 (was bit 0 - defeated the bus-key fail-loud gate); cc_id read from offset 14; title_cps_unit range-validated + 1->0 index-converted per libaacs. Corrected attack_crib ("functionally-equivalent" not "exact" port) and read_disc_key (READ DVD STRUCTURE 0xAD, not REPORT KEY) doc comments.
Also includes accumulated uncommitted work: key-fetch seam and TrueHD/DTS audio fix.
Matthew Jackson