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

phase, verified, status, score, re_verification, human_verification

phase	verified	status	score	re_verification	human_verification
06-obfuscation-hardening	2026-02-24T23:32:25Z	human_needed	4/4	false	test expected why_human Run Kotlin cross-validation tests with kotlinc/java installed All 6 tests pass (Rust pack -> Kotlin decode -> SHA-256 match) kotlinc and java are not available in the current environment; Kotlin code is structurally verified but not runtime-tested

Phase 6: Obfuscation Hardening Verification Report

Phase Goal: Archive format resists casual analysis -- binwalk, file, strings, and hex editors reveal nothing useful Verified: 2026-02-24T23:32:25Z Status: human_needed Re-verification: No -- initial verification

Goal Achievement

Observable Truths

#	Truth	Status	Evidence
1	File table (names, sizes, offsets) is encrypted with its own IV -- hex dump of archive reveals no plaintext metadata	VERIFIED	TOC encrypted via crypto::encrypt_data(&toc_plaintext, &KEY, &toc_iv) in archive.rs:162,195. strings on archive reveals no filenames. Tested with multi-file archive -- no "hello", "test", ".txt" in output.
2	All headers are XOR-obfuscated with a fixed key -- no recognizable structure patterns in first 256 bytes	VERIFIED	First bytes of archive are a5d6 e46c e074 4cc8 instead of 00ea7263. XOR_KEY [0xA5, 0x3C, 0x96, 0x0F, 0xE1, 0x7B, 0x4D, 0xC8] applied in archive.rs:216-217 via format::xor_header_buf().
3	Random decoy padding exists between data blocks -- file boundaries are not detectable by size analysis	VERIFIED	rng.random_range(64..=4096) generates random padding (archive.rs:111). Random bytes written after each ciphertext block (archive.rs:231). inspect shows Padding after: 1718 bytes for test archive.
4	All three decoders (Rust, Kotlin, Shell) still produce byte-identical output after obfuscation is applied	VERIFIED (partial: Kotlin not runtime-tested)	Rust: 38 cargo tests pass (25 unit + 7 golden + 6 round-trip). Shell: 7/7 cross-validation tests pass. Kotlin: code structurally correct (XOR bootstrapping, TOC decryption) but kotlinc/java not available in environment.

Score: 4/4 truths verified (1 needs human runtime confirmation for Kotlin)

Required Artifacts

Artifact	Expected	Status	Details
src/format.rs	XOR_KEY constant, xor_header_buf(), read_header_auto() with XOR bootstrapping	VERIFIED	XOR_KEY at line 13, xor_header_buf() at line 85, read_header_auto() at line 149, write_header_to_buf() at line 95, serialize_toc() at line 171, read_toc_from_buf() at line 182, parse_header_from_buf() at line 111. 6 new XOR-related unit tests (lines 509-661).
src/archive.rs	Updated pack() with TOC encryption + decoy padding + XOR header; updated unpack()/inspect() with de-obfuscation	VERIFIED	pack() at line 58: TOC encryption (lines 160-163), decoy padding (lines 111-113), XOR header (lines 216-217). read_archive_metadata() shared helper at line 32 for unpack/inspect de-obfuscation.
src/crypto.rs	generate_iv() used for toc_iv	VERIFIED	generate_iv() at line 8, encrypt_data() at line 18, decrypt_data() at line 34. Used by archive.rs for toc_iv generation.
kotlin/ArchiveDecoder.kt	XOR_KEY constant, xorHeader(), TOC decryption, updated decode()	VERIFIED	XOR_KEY at line 39, xorHeader() at line 266, XOR bootstrapping in decode() at line 293-296, TOC decryption at lines 302-315.
shell/decode.sh	XOR_KEY_HEX, XOR de-obfuscation loop, TOC decryption via openssl, TOC_FILE abstraction	VERIFIED	XOR_KEY_HEX at line 107, hex_to_bin() at line 113, XOR bootstrapping loop at lines 138-161, header temp file parsing at lines 164-181, TOC decryption at lines 188-204, TOC_FILE/TOC_BASE_OFFSET abstraction throughout TOC parsing loop.
kotlin/test_decoder.sh	Cross-validation tests using obfuscated archives	VERIFIED	5 test cases (single text, multiple files, no-compress, empty file, large file) with SHA-256 verification.
shell/test_decoder.sh	Cross-validation tests using obfuscated archives	VERIFIED	6 test cases (single text, multiple files, no-compress, empty file, large file, Cyrillic filename) with SHA-256 verification. All 7 file verifications pass.

Key Link Verification

From	To	Via	Status	Details
archive.rs pack()	format.rs xor_header_buf()	XOR applied to 40-byte header buffer after write_header_to_buf	WIRED	archive.rs:216 write_header_to_buf, line 217 xor_header_buf
archive.rs pack()	crypto.rs encrypt_data()	TOC plaintext buffer encrypted with toc_iv	WIRED	archive.rs:162 crypto::encrypt_data(&toc_plaintext, &KEY, &toc_iv), line 195 re-encryption with correct offsets
archive.rs unpack()/inspect()	format.rs read_header_auto() + crypto.rs decrypt_data()	XOR bootstrapping on header, then TOC decryption	WIRED	read_archive_metadata() at line 32-51: read_header_auto (line 34), decrypt_data for TOC (line 43)
kotlin decode()	xorHeader()	XOR bootstrapping on header bytes before parseHeader	WIRED	ArchiveDecoder.kt:293-296: magic check, xorHeader(headerBytes) call
kotlin decode()	decryptAesCbc()	Encrypted TOC bytes decrypted with tocIv before parseToc	WIRED	ArchiveDecoder.kt:307 decryptAesCbc(encryptedToc, header.tocIv, KEY)
shell decode.sh	openssl enc -d	Encrypted TOC extracted and decrypted	WIRED	decode.sh:192 dd extract, lines 195-197 openssl decrypt, TOC_FILE variable set to decrypted temp file

Requirements Coverage

Requirement	Source Plan	Description	Status	Evidence
FMT-06	06-01, 06-02	XOR-obfuscation of headers with fixed key	SATISFIED	XOR_KEY constant identical across all 3 implementations. Header bytes obfuscated -- first 4 bytes are a5d6e46c not 00ea7263. XOR bootstrapping in all decoders.
FMT-07	06-01, 06-02	Encrypted file table with separate IV	SATISFIED	TOC encrypted via AES-256-CBC with random toc_iv stored in header. All 3 decoders decrypt TOC before parsing entries. strings reveals no filenames.
FMT-08	06-01, 06-02	Decoy padding (random data between blocks)	SATISFIED	Random padding 64-4096 bytes per file (archive.rs:111). Random bytes via rand::Fill (line 113). All decoders use absolute data_offset from TOC entries, naturally skipping padding.

Anti-Patterns Found

File	Line	Pattern	Severity	Impact
src/archive.rs	140,148	"placeholder" in comment about data_offset=0	Info	Not a stub -- placeholder offsets are immediately replaced with real values at line 185 in the two-pass algorithm. No issue.

Human Verification Required

1. Kotlin Cross-Validation Tests

Test: Run bash kotlin/test_decoder.sh on a system with kotlinc and java installed Expected: All 6 tests pass (Rust pack with obfuscation -> Kotlin decode -> SHA-256 match) Why human: kotlinc and java are not installed in the current environment. The Kotlin code is structurally verified (XOR_KEY, xorHeader(), TOC decryption all present and correctly wired), but has not been runtime-tested in this verification cycle.

Gaps Summary

No gaps found. All four success criteria from the ROADMAP are met:

1. File table encrypted with its own IV -- hex dump reveals no plaintext metadata (verified with strings scan)
2. Headers XOR-obfuscated -- no recognizable structure in first bytes (verified: a5d6e46c instead of 00ea7263)
3. Random decoy padding between blocks -- file boundaries not detectable (verified: Padding after: 1718 bytes in inspect output)
4. All three decoders produce byte-identical output -- Rust 38/38 tests pass, Shell 7/7 cross-validation pass, Kotlin structurally verified (needs runtime confirmation)

All 38 Rust tests pass (25 unit + 7 golden + 6 round-trip integration). All 7 Shell cross-validation tests pass. The only item requiring human action is running the Kotlin cross-validation tests with kotlinc/java installed.

Requirements FMT-06, FMT-07, FMT-08 are all satisfied with implementation evidence across all three decoder implementations.

---

Verified: 2026-02-24T23:32:25Z Verifier: Claude (gsd-verifier)