e2891de712
The Crypt filter was already implemented in the codebase. This note documents the verification of acceptance criteria and test coverage. Acceptance criteria verified: - /Identity crypt passes through unchanged - Custom crypt returns ENCRYPTION_UNSUPPORTED - Missing /DecodeParms defaults to /Identity - Works correctly with FlateDecode - Comprehensive test coverage including proptests - INV-8 maintained (no panics) Also add missing malformed fixture entries to PROVENANCE.md. Co-Authored-By: Claude Code <noreply@anthropic.com>
61 lines
2.5 KiB
Markdown
61 lines
2.5 KiB
Markdown
# pdftract-15cs8: Crypt Filter Implementation Verification
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## Task Summary
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Implement Crypt filter (identity only, custom rejected with ENCRYPTION_UNSUPPORTED)
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## Finding
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The Crypt filter implementation was **already complete** in the codebase. No changes were required.
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## Implementation Location
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- File: `crates/pdftract-core/src/parser/stream.rs`
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- Lines: 795-885 (CryptDecoder struct and implementation)
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- Registered in get_decoder: line 960
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- Orchestrator error handling: lines 1460-1471
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## Acceptance Criteria Status
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| Criteria | Status | Location |
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|----------|--------|----------|
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| /Crypt with /Name /Identity passes through unchanged | ✅ PASS | Lines 850-851 |
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| /Crypt with /Name /MyCustom returns ENCRYPTION_UNSUPPORTED | ✅ PASS | Lines 853-854 |
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| /Crypt with no /DecodeParms defaults to /Identity | ✅ PASS | Lines 822-825 |
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| /Crypt with /Identity + FlateDecode works correctly | ✅ PASS | Test line 2678 |
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| proptest never panics | ✅ PASS | Tests lines 2879, 2892 |
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| INV-8 maintained (no panics) | ✅ PASS | Returns Err for hard errors |
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## Test Coverage
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The implementation includes comprehensive tests:
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- `test_crypt_decode_identity` - Line 2579
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- `test_crypt_decode_custom_rejected` - Line 2605
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- `test_crypt_decode_no_params` - Line 2632
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- `test_crypt_decode_missing_name` - Line 2652
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- `test_crypt_identity_then_flate` - Line 2678
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- `test_crypt_decoder_invalid_params` - Line 2709
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- `test_crypt_decode_bomb_limit` - Line 2755
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- `test_crypt_decoder_name` - Line 2778
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- `test_crypt_custom_names_rejected` - Line 2784
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- `proptest_crypt_decode_no_panic` - Line 2879
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- `proptest_crypt_decode_with_params_no_panic` - Line 2892
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- `proptest_crypt_decode_bomb_limit_no_panic` - Line 2926
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## Implementation Details
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### Public API
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- `CryptDecoder` implements `StreamDecoder` trait
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- `decode()` method checks `/DecodeParms /Name`
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- `/Identity` (or missing): pass through unchanged
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- Custom name: returns `FilterError::EncryptionUnsupported`
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### Orchestrator Integration
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The orchestrator catches `FilterError::EncryptionUnsupported` and:
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1. Emits `ENCRYPTION_UNSUPPORTED` diagnostic
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2. Returns empty bytes for the stream
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3. Marks the stream as undecryptable
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### INV-8 Compliance
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- No panics in the implementation
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- Hard errors return `Err(FilterError::EncryptionUnsupported)`
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- Corrupt data mid-stream would return `Ok(partial)` with diagnostic (not applicable for Crypt since it's a no-op)
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## Conclusion
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The Crypt filter is fully implemented per PDF spec 7.4.10 and meets all acceptance criteria. No changes required.
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