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feat(sdk): read deflate-compressed ZIP entries in TDF archives - #4247
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OpenTDF writers store both TDF entries uncompressed, but other ZTDF/TDF writers compress them with DEFLATE (method 8). The reader ignored the compression method and returned the compressed bytes as entry content, so such archives failed later with a misleading JSON parse or segment integrity error. The zipstream reader now accepts STORED (0) and DEFLATE (8) entries and rejects any other method when the archive is opened, with ErrUnsupportedCompression naming the entry and the method. Writers are unchanged and still emit STORED entries. For a deflated entry the compressed size from the central directory (including ZIP64) bounds what is read from the archive and the declared uncompressed size is its logical length. Inflation never runs more than one byte past the declared size, and a stream that inflates to more or fewer bytes is an error. A declared size beyond DEFLATE's 1032:1 limit is rejected up front, and read buffers grow with inflated data rather than being sized from the declaration. The manifest size cap applies to the uncompressed size and is checked before any data is read. Payload reads stay in uncompressed coordinates. A deflated payload is inflated sequentially with a forward cursor rather than buffered whole: reads ahead skip forward, reads behind restart from the entry start, and the last range read is kept so the repeated segment fetches the sdk's Read makes stay linear. Access to the shared ReadSeeker and the cursor is serialized with a mutex. No CRC-32 check is made; TDF segment hashes and the root signature already cover integrity. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Signed-off-by: Paul Flynn <pflynn-virtru@users.noreply.github.com>
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Deflated TDF entries are now decoded by archive/zip instead of a hand-built inflater. archive/zip owns decompression, enforcement of the declared uncompressed size (ErrFormat past it, io.ErrUnexpectedEOF short of it), CRC-32 verification (ErrChecksum) when an entry is read to the end, and ZIP64 and data-descriptor handling. The custom entry source, size and end checks, method-name table and 1032:1 ratio check are removed; bounded buffer growth already keeps a forged declared size from forcing a large allocation. The zip.Reader is built lazily over the archive's ReadSeeker, through a ReaderAt adapter used under the existing mutex, and only on the first read of a deflated entry. Archives holding only STORED entries, which is every archive OpenTDF writes, never touch archive/zip and keep the existing path. Each deflated entry is matched to its zip.File by data offset as well as name, and archive/zip must agree on its method and sizes, so duplicate names cannot cross-wire and the bounds NewReader checks still hold. Methods other than STORED and DEFLATE are still refused when the archive is opened, now wrapping the exported zip.ErrAlgorithm so callers outside the SDK can test for it. zipstream keeps only what archive/zip does not provide: a forward cursor over the opened entry for random-access payload reads, the last-range cache that keeps the sdk's repeated segment reads linear, the manifest cap checked against the uncompressed size before reading, and buffers that grow with the inflated data. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Signed-off-by: Paul Flynn <pflynn-virtru@users.noreply.github.com>
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Inline comments:
Review comments at @sdk/internal/zipstream/reader.go:
- Around line 507-557: Update the zero-length fast path in ReadFileData so it
returns immediately for deflated entries only when index is not at the declared
end, while allowing an end-position read to open and validate the DEFLATE
stream. Preserve the existing bounds checks and empty result for non-end
zero-length reads.
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sdk/internal/zipstream/fuzz_test.gosdk/internal/zipstream/inflate.gosdk/internal/zipstream/inflate_test.gosdk/internal/zipstream/reader.gosdk/internal/zipstream/zip64_conformance_test.gosdk/tdf_test.go
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ReadFileData short-circuited every zero-length read of a deflated entry, so an empty read at the declared end skipped the end-of-stream and CRC-32 checks that any other read reaching the end gets. An entry declaring zero bytes over real data read back as empty. Only skip inflation when the empty read is short of the end. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Signed-off-by: Paul Flynn <pflynn-virtru@users.noreply.github.com>
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A stored manifest can never be longer than its archive, but DEFLATE expands about 1000 times. With no manifest size limit configured, which is the default and the only behavior IsValidTdf has, a few-MB archive could make the reader inflate and allocate gigabytes for a deflated manifest before anything validated it. The Reader now carries an inflation budget, the larger of the archive's length and 10 MiB. ReadAllFileData holds a deflated entry to it when called with math.MaxInt64, which is what TDFReader passes when no limit is configured; any other limit applies as given, even above the budget, which is how a caller admits a legitimately large compressed manifest. ReadFileData refuses a deflated entry declaring more than the budget outright: payload ciphertext does not compress, so a real deflated payload never declares more than its archive holds. Both checks run on the declared uncompressed size before any entry data is read, and since archive/zip stops one byte past that size, bounding it bounds inflation. The errors wrap errZipFileSizeError and say how to proceed. Stored entries are unchanged. The WithMaxManifestSize godoc now describes the cap on compressed manifests and the override. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Signed-off-by: Paul Flynn <pflynn-virtru@users.noreply.github.com>
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The zipstream reader never looked at an entry's compression method and returned its bytes verbatim, so IsValidTdf accepted, and LoadTDF tried to decrypt, a deflated 0.payload as if it were ciphertext. It did the same for method 8 declared over bytes that are not compressed. web-sdk rejects both. The TDF container profile stores both entries uncompressed, and every OpenTDF writer emits STORED entries. NewReader now refuses any entry whose central directory record declares a method other than 0, with an error wrapping zip.ErrAlgorithm. This is a policy choice, kept in its own commit so it can be dropped: #4247 and opentdf/java-sdk#424 instead add DEFLATE reading to the Go and Java readers. Which way the SDKs go is open under DSPX-4924. Signed-off-by: Dave Mihalcik <dmihalcik@virtru.com>
Proposed Changes
OpenTDF writers store both TDF entries (
0.payloadand the manifest) uncompressed, but other ZTDF/TDF writers compress them with DEFLATE (ZIP method 8). The Go reader ignored the compression method and returned an entry's compressed bytes as its content, so those archives failed later with a misleading JSON parse error or a segment integrity failure. This PR reads deflated entries through the standard library'sarchive/zip, and rejects every other method with a clear error.archive/zipreader is built lazily, on the first read of a DEFLATE entry, so an archive with no deflated entries never touchesarchive/zip. A test pins this.archive/ziphandles deflated entries. It decompresses them, enforces the declared uncompressed size (zip.ErrFormatfor data past it,io.ErrUnexpectedEOFfor data short of it), and verifies the CRC-32 (zip.ErrChecksum). It also handles ZIP64 and data descriptors.io.ReaderAtadapter over the caller'sReadSeeker. Size comes fromSeek(0, io.SeekEnd), and every access happens under the reader's existing mutex.*zip.Fileby data offset (File.DataOffset()) as well as name, so duplicate names can't get crossed.archive/zipmust also report the same method and sizes, so the boundsNewReaderalready checks (entry data never reaches into the central directory) hold for whatarchive/zipreads.NewReader, so alsoLoadTDFandIsValidTdf). The error wraps the exportedzip.ErrAlgorithm, so callers outside the SDK can useerrors.Is(err, zip.ErrAlgorithm). The message names the entry and the method, e.g.zip: unsupported compression algorithm: entry "0.payload" uses compression method 12; only stored (0) and deflate (8) are supported.ReadPayload/ReadFileDatakeep taking uncompressed(index, length). A deflated payload is never buffered whole. A forward cursor runs over theReadCloserfromFile.Open():io.CopyN(io.Discard, ...).archive/zipcheck that the stream ends there and verify the CRC.Readfetches the whole current segment on every call throughReadAt. A caller reading in small pieces therefore asks for the same segment many times in a row, and without the cache each repeat would re-open and re-inflate the entry, making a sequentialRead/io.ReadAllquadratic. The last range returned is kept, callers get copies, and a test pins that a sequential pass stays linear.WithMaxManifestSize/WithTDFManifestMaxSizeis checked against the declared uncompressed size before any entry data is read.IsValidTdf, which has no limit option) would let a few-MB archive inflate to gigabytes before anything validated it. EachReadertherefore carries a budget: the larger of the archive's length and 10 MiB (minInflateBudget). Both checks below use the declared uncompressed size and run before any entry data is read. Becausearchive/zipstops one byte past the declared size, bounding the declared size bounds inflation. Both errors wrap the existing file-size error and say what to do.TDFReaderpasses toReadAllFileDataasmath.MaxInt64, a deflated manifest must declare no more than the budget. An explicit limit applies as given, even above the budget; that is how to read a legitimately large compressed manifest. TheWithMaxManifestSizegodoc says this.ReadFileDatarejects a deflated payload that declares more than the budget, with no override. Payload ciphertext does not compress, so a real deflated payload never declares more than its archive holds.archive/zipreports the shortfall.MaxInt64, which can't be represented. The 1032:1 DEFLATE-ratio check from the first revision is gone:archive/zipstops one byte past the declared size, and the budget plus growing buffers prevent over-allocation, so the ratio check added no protection.WriteTo,io.Copy, sequentialRead,Seekforward) costs one pass.archive/zippulls compressed data 4 KiB at a time through flate's buffered reader. Each of those pulls is one seek and one read on the archiveReadSeeker.Reader, serializes access to the archiveReadSeekerand the deflated entries' cursors. As a side effect, concurrentReadAtcalls on stored payloads are now safe too. Before, they raced on the sharedSeek+Read.tdf3_reader.goandzip_headers.goalone so this doesn't conflict with the open manifest-name PRs.Checklist
Testing Instructions
sdk/internal/zipstream/inflate_test.gocovers:ReadSeeker.TDFReaderwith a deflated manifest and/or payload, under bothmanifest.jsonand0.manifest.json, in all four stored/deflated combinations, with segments read in reverse.zip.ErrAlgorithm, and the message names the entry and the method.zip.ErrFormat; larger givesio.ErrUnexpectedEOF.zip.ErrChecksumon full reads of the manifest and the payload, and partial reads still succeed.archive/zipitself, with data descriptors.archive/zip, and thezip.Readeris built only on the first deflated read.zip.ErrFormatafter reading only a fraction of the compressed data.NewTDFReader+ManifestpathIsValidTdfuses), a sub-1 MiB archive whose deflated manifest declares more than 10 MiB is refused with zero entry bytes read, and an explicit larger limit admits it. A manifest within the budget reads by default. An archive longer than 10 MiB raises the budget to its own length. A deflated payload declaring more than the budget is refused byReadPayload. Insdk/manifest_size_test.go,TestIsValidTdf_DeflatedManifestInflationBudgetcovers the same case throughIsValidTdf.-race.MaxInt64is rejected at open. A terabyte declared size is refused by the budget by default, and under an explicit limit it does not allocate up front.Other test changes:
FuzzReaderhas seeds for both entries deflated with ZIP64, an overdeclared deflated entry, and bzip2. In-range reads of deflated entries may fail, but never with partial data.sdk/tdf_test.goTest_DeflatedZipEntries: the SDK writes a TDF,archive/ziprewrites it with deflated entries under both manifest names, and the SDK decrypts it end to end withWriteTo, reverseReadAt, andSeek+Read.Run:
Cross-SDK verification
xtest run opentdf/tests actions/runs/39625561654 (2026-10-21) built the platform and otdfctl from opentdf/platform
feat/zip-inbound-deflate(553e9623), java-sdkfeat/zip-inbound-deflate(b02a4121) and web-sdkfeat/zip-inbound-deflate(94e09e4d), and rantest_tdf_roundtrip_deflated_entriesfrom opentdf/tests#671 withforce-supports=zip-deflate. The test encrypts with one SDK, rewrites every ZIP entry with DEFLATE, checks the entries are compressed, and decrypts with another SDK.All 9 cells ran (none skipped) and passed:
This PR is the reader in the go column.
For comparison, the same test fails wherever an SDK built from
maindecrypts (opentdf/tests#671 CI):json.Unmarshal failed: invalid character 'u' looking for beginning of valueInvalidZipException: Archive ended 1110 bytes into the 1438 byte entry [0.manifest.json]InvalidFileError: entry [0.payload] uses unsupported compression method [8]🤖 Generated with Claude Code
Summary by CodeRabbit
New Features
Bug Fixes