Files
pdfcraft/crates/redact/src/verify
d7ce875dd6 redact: independent redaction proof machinery (snapshot, sweep, budget) (#5557)
* redact: add the independent redaction proof machinery

* redact: harden the proof's paint check and count removed codes

The manifest counts character codes, not raw bytes: a composite font's
codes are several bytes, so the byte length overstated what was cut.

Annotation appearances are checked whatever their storage (a direct
dictionary has no reference of its own to dedupe on), and a stream
shared by several annotations is checked at each annotation's own
placement. The graphics-state stack and the clip holes of one walk are
bounded; deeper or more is unverifiable, never unbounded memory.
Even-odd clips cut holes only where the rule can be told cheaply - all
subpaths axis-aligned, disjoint, few - and anything else keeps its
paint reported, failing closed. The /W widths of a descendant font
cost bounded work, like a CMap.

* redact: settle the survivors a page sweep counted before its work ran out

A page that the search budget stops on left the counts made on earlier
pages unsettled: the survivors were seen but never reported, and the
regions that owned them were never marked. The sweep now stops and
still settles, so a located survivor is reported where it sits (the
page reads unswept either way, and the proof still fails).

* redact: prove the redacted output of every supported encryption

The authenticated-reopen regression now covers all four crypt
algorithms the writer supports, not only AES-128: the caller's
credentials prove the saved output, and empty or wrong credentials
still fail closed.

* redact: answer the review round on the proof

A glyph lying under several regions is now accounted for by every one
of them, so overlapping marks each carry their own share in a shared
proof instead of the first one absorbing the rest and the others
reading as if no text was there.

Each finding is recorded once per region as it is found, so a page
that paints over a region a thousand times neither grows the report
nor the memory with repeats.

The byte search walks the haystack once (the pattern's prefix function
is built once), so a needle of one letter over a haystack full of it
can no longer spend comparisons the search budget never charged for.

A numeric XML character reference may carry any number of leading
zeros; the padded form now decodes like the short one, so a survivor
spelled that way in the XMP is still found.

The /W widths of a descendant font are paid for from the shared work
budget: a form invoked again rebuilds its fonts, and a per-font
counter alone let the same array be paid for many times over.

* redact: sweep the proof's survivors out of every place a reader could look

Plant the removed text where the review listed it and expect the sweep to
report it: a compressed object stream, a page thumbnail, a form field
value, an XFA packet, and an object nothing refers to. A file whose page
content is bigger than the proof may decode for one stream is now shown
to come out unverified on its surfaces and its region, never clean.

* redact: spare the names a redacted word legitimately sits in, and charge failed decodes

A redacted word that is also a structural name (a /Subtype, a /Filter, a
/BaseFont) is structure, not a leftover copy: the name surface is now
swept against the matches the input itself had, and only a surplus of
matches is a survivor. The input's names are counted when the snapshot is
taken, for the region's needles and for strings added later alike.

A decode that fails after doing part of its work paid nothing: the
proof's cumulative decode allowance now charges every attempt, failures
included, so the same bomb cannot be decoded (and fail) again and again
for free.

* redact: count the input's names once each, and say so when the count runs out

The name allowance counted one entry per occurrence, so a document whose
pages repeat the same structural name paid for the same scan again and
again; names are now kept once, with their count. A name search that runs
out of work read as no matches, which would have swept names with none
allowed: that is reported on the text surface now, and the proof fails
rather than pass on an uncounted allowance.

* Bound redaction proof searches across many needles

Assisted-by: OpenAI Codex

* Redaction proof: drop find_all, which nothing calls

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Cargo.lock: put aho-corasick in its sorted place

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Redaction proof: review notes

A word split across a TJ array is looked for whole. Overlapping marks count a
removed copy once. A spent decode budget is a problem, not a raw-only stream.
Short needles stay out of the attachment text search, and an indirect /Decode
counts.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: eliets2 <287273517+eliets2@users.noreply.github.com>
Co-authored-by: FredApps <FredApps@users.noreply.github.com>
Co-authored-by: FredApps <153173854+FredApps@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
2026-11-06 09:15:07 +01:00
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