android-encrypted-archiver/.planning/phases/06-obfuscation-hardening/06-01-SUMMARY.md

phase, plan, subsystem, tags, requires, provides, affects, tech-stack, key-files, key-decisions, patterns-established, requirements-completed, duration, completed

phase	plan	subsystem	tags	requires	provides	affects	tech-stack	key-files	key-decisions	patterns-established	requirements-completed	duration	completed
06-obfuscation-hardening	01	crypto	xor aes-256-cbc obfuscation binary-format padding	phase provides 02-core-archiver pack/unpack/inspect pipeline with AES-256-CBC encryption phase provides 03-round-trip-verification unit tests, golden vectors, integration tests	XOR header obfuscation with cyclic 8-byte key AES-256-CBC encrypted TOC with random toc_iv Decoy random padding (64-4096 bytes) between data blocks XOR bootstrapping auto-detection (plain vs obfuscated headers) Buffer-based header/TOC serialization helpers	06-02 (Kotlin/Shell decoder updates) cross-validation tests	added patterns xor-header-obfuscation toc-encryption decoy-padding read_archive_metadata-helper	created modified src/format.rs src/archive.rs	Always enable all 3 obfuscation features (no --no-obfuscate flag in v1) Decoy padding range 64-4096 bytes per file (FORMAT.md allows up to 65535) Shared read_archive_metadata() helper for unpack/inspect de-obfuscation Two-pass TOC serialization: first pass for size, second with correct data_offsets	XOR bootstrapping: check magic first, attempt XOR de-obfuscation on mismatch Buffer-based serialization: write_header_to_buf() and serialize_toc() for encryption pipeline read_archive_metadata() as shared de-obfuscation entry point	FMT-06 FMT-07 FMT-08	3min	2026-02-25

Phase 6 Plan 1: Rust Obfuscation Pipeline Summary

XOR-obfuscated headers, AES-encrypted TOC, and random decoy padding in Rust archiver with full backward-compatible decode

Performance

• Duration: 3 min
• Started: 2026-02-24T23:16:21Z
• Completed: 2026-02-24T23:20:06Z
• Tasks: 2/2
• Files modified: 2

Accomplishments

• Archives are completely unrecognizable: no magic bytes, no plaintext filenames, no detectable structure
• Flags byte is 0x0F when compression + all 3 obfuscation features are active
• All 38 existing tests pass (25 unit + 7 golden + 6 round-trip integration) -- zero failures
• XOR bootstrapping allows transparent detection of both plain and obfuscated headers

Task Commits

Each task was committed atomically:

1. Task 1: Add XOR header obfuscation and TOC encryption to format.rs - 8ac2512 (feat)
2. Task 2: Update pack/unpack/inspect with full obfuscation pipeline - b6fa51d (feat)

Files Created/Modified

• 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
• src/archive.rs - Updated pack() with TOC encryption + decoy padding + XOR header; updated unpack()/inspect() with shared read_archive_metadata() de-obfuscation helper

Decisions Made

• Always enable all 3 obfuscation features in pack() -- no opt-out flag in v1 (the whole point is hardening)
• Decoy padding range 64-4096 bytes per file -- meaningful noise without significant size inflation
• 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)
• Shared read_archive_metadata() function factored out for both unpack() and inspect() to avoid code duplication

Deviations from Plan

None - plan executed exactly as written.

Issues Encountered

None

User Setup Required

None - no external service configuration required.

Next Phase Readiness

• Rust archiver produces fully obfuscated archives; decoders will use same de-obfuscation patterns
• Plan 06-02 should update Kotlin ArchiveDecoder.kt and Shell decode.sh to handle XOR headers, encrypted TOC, and padding_after > 0
• Cross-validation tests should confirm byte-identical extraction across all three decoders

Self-Check: PASSED

• FOUND: src/format.rs
• FOUND: src/archive.rs
• FOUND: 06-01-SUMMARY.md
• FOUND: commit 8ac2512
• FOUND: commit b6fa51d

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Phase: 06-obfuscation-hardening Completed: 2026-02-25