4eaedc2872
- Add 06-01-SUMMARY.md with execution results - Update STATE.md: phase 6, plan 1/2, 90% progress - Update ROADMAP.md: phase 06 plan progress 1/2 - Mark FMT-06, FMT-07, FMT-08 complete in REQUIREMENTS.md Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
111 lines
4.2 KiB
Markdown
111 lines
4.2 KiB
Markdown
---
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phase: 06-obfuscation-hardening
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plan: 01
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subsystem: crypto
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tags: [xor, aes-256-cbc, obfuscation, binary-format, padding]
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# Dependency graph
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requires:
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- phase: 02-core-archiver
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provides: pack/unpack/inspect pipeline with AES-256-CBC encryption
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- phase: 03-round-trip-verification
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provides: unit tests, golden vectors, integration tests
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provides:
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- XOR header obfuscation with cyclic 8-byte key
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- AES-256-CBC encrypted TOC with random toc_iv
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- Decoy random padding (64-4096 bytes) between data blocks
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- XOR bootstrapping auto-detection (plain vs obfuscated headers)
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- Buffer-based header/TOC serialization helpers
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affects: [06-02 (Kotlin/Shell decoder updates), cross-validation tests]
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# Tech tracking
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tech-stack:
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added: []
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patterns: [xor-header-obfuscation, toc-encryption, decoy-padding, read_archive_metadata-helper]
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key-files:
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created: []
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modified:
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- src/format.rs
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- src/archive.rs
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key-decisions:
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- "Always enable all 3 obfuscation features (no --no-obfuscate flag in v1)"
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- "Decoy padding range 64-4096 bytes per file (FORMAT.md allows up to 65535)"
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- "Shared read_archive_metadata() helper for unpack/inspect de-obfuscation"
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- "Two-pass TOC serialization: first pass for size, second with correct data_offsets"
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patterns-established:
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- "XOR bootstrapping: check magic first, attempt XOR de-obfuscation on mismatch"
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- "Buffer-based serialization: write_header_to_buf() and serialize_toc() for encryption pipeline"
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- "read_archive_metadata() as shared de-obfuscation entry point"
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requirements-completed: [FMT-06, FMT-07, FMT-08]
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# Metrics
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duration: 3min
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completed: 2026-02-25
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---
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# Phase 6 Plan 1: Rust Obfuscation Pipeline Summary
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**XOR-obfuscated headers, AES-encrypted TOC, and random decoy padding in Rust archiver with full backward-compatible decode**
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## Performance
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- **Duration:** 3 min
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- **Started:** 2026-02-24T23:16:21Z
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- **Completed:** 2026-02-24T23:20:06Z
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- **Tasks:** 2/2
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- **Files modified:** 2
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## Accomplishments
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- Archives are completely unrecognizable: no magic bytes, no plaintext filenames, no detectable structure
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- Flags byte is 0x0F when compression + all 3 obfuscation features are active
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- All 38 existing tests pass (25 unit + 7 golden + 6 round-trip integration) -- zero failures
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- XOR bootstrapping allows transparent detection of both plain and obfuscated headers
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## Task Commits
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Each task was committed atomically:
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1. **Task 1: Add XOR header obfuscation and TOC encryption to format.rs** - `8ac2512` (feat)
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2. **Task 2: Update pack/unpack/inspect with full obfuscation pipeline** - `b6fa51d` (feat)
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## Files Created/Modified
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- `src/format.rs` - Added XOR_KEY constant, xor_header_buf(), write_header_to_buf(), read_header_auto() with XOR bootstrapping, serialize_toc(), read_toc_from_buf(), parse_header_from_buf(), plus 6 new unit tests
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- `src/archive.rs` - Updated pack() with TOC encryption + decoy padding + XOR header; updated unpack()/inspect() with shared read_archive_metadata() de-obfuscation helper
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## Decisions Made
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- Always enable all 3 obfuscation features in pack() -- no opt-out flag in v1 (the whole point is hardening)
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- Decoy padding range 64-4096 bytes per file -- meaningful noise without significant size inflation
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- Two-pass TOC serialization approach: first serialize with placeholder offsets to determine encrypted TOC size, then re-serialize with correct data_offsets and re-encrypt (encrypted size is identical because plaintext length is unchanged)
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- Shared read_archive_metadata() function factored out for both unpack() and inspect() to avoid code duplication
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## Deviations from Plan
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None - plan executed exactly as written.
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## Issues Encountered
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None
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## User Setup Required
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None - no external service configuration required.
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## Next Phase Readiness
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- Rust archiver produces fully obfuscated archives; decoders will use same de-obfuscation patterns
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- Plan 06-02 should update Kotlin ArchiveDecoder.kt and Shell decode.sh to handle XOR headers, encrypted TOC, and padding_after > 0
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- Cross-validation tests should confirm byte-identical extraction across all three decoders
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## Self-Check: PASSED
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- FOUND: src/format.rs
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- FOUND: src/archive.rs
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- FOUND: 06-01-SUMMARY.md
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- FOUND: commit 8ac2512
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- FOUND: commit b6fa51d
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---
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*Phase: 06-obfuscation-hardening*
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*Completed: 2026-02-25*
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