ImpTune/.planning/phases/01-foundation/01-03-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
01-foundation	03	infra	intunewin pycryptodome aes-256-cbc hmac-sha256 python zipfile		build_intunewin() function: Python-native .intunewin assembler using pycryptodome 14 byte-level validation tests for .intunewin format compliance Verified encrypted blob layout: HMAC(32) + IV(16) + AES-256-CBC ciphertext Detection.xml schema with all 8 EncryptionInfo sub-elements and correct namespace	05-export (uses build_intunewin directly for Intune package generation)	added patterns pycryptodome 3.20.x — AES-256-CBC encryption and PKCS7 padding pytest — test runner (already required) TDD: failing tests committed first, then implementation Encrypted blob layout: HMAC(32) + IV(16) + ciphertext (AES-256-CBC) Inner ZIP uses DEFLATE; outer ZIP uses STORED (no double-compression of encrypted content) All crypto values in Detection.xml use standard base64 encoding	created modified imptune/generators/intunewin_builder.py imptune/generators/__init__.py tests/test_intunewin.py tests/__init__.py	IV is 16 bytes (not 32) — corrected from STACK.md documentation error; aligns with AES standard and svrooij.io verification MacKey is 32 bytes — same size as EncryptionKey, consistent with SvRooij.ContentPrep behavior Inner ZIP uses DEFLATE compression (matches C# reference implementation .NET default) Real Intune upload validation deferred to Phase 5 gate — local byte-level tests are necessary but not sufficient	Pattern: .intunewin encrypted blob = HMAC-SHA256(32) + IV(16) + AES-256-CBC-ciphertext Pattern: build_intunewin(source_dir, setup_file, output_path) is the public API Pattern: All crypto roundtrip tests in test_intunewin.py verify encrypt-then-decrypt recovers original files	INFRA-02	7min	2026-04-10

Phase 1 Plan 03: .intunewin Builder Summary

Python-native .intunewin assembler using pycryptodome: AES-256-CBC encryption with HMAC-SHA256, producing the exact 48-byte header + ciphertext blob layout that Intune expects

Performance

• Duration: ~7 min
• Started: 2026-04-10T09:23:18Z
• Completed: 2026-04-10T09:25:32Z
• Tasks: 1 (TDD: RED + GREEN commits)
• Files modified: 4

Accomplishments

• Implemented build_intunewin(source_dir, setup_file, output_path) as a standalone Python module requiring no external binary (INFRA-02)
• All 14 byte-level tests pass: outer ZIP structure, Detection.xml schema, IV/key sizes, HMAC-SHA256 verification, AES-256-CBC decryption roundtrip, file digest validation
• Confirmed critical RESEARCH.md correction: IV is 16 bytes (not 32 as incorrectly documented in STACK.md)
• Highest-risk unknown in Phase 1 is now validated at the byte-level; only a real Intune tenant upload remains outstanding

Task Commits

Each task was committed atomically using TDD:

1. RED — Failing tests - 4d455e7 (test)
2. GREEN — Implementation - 25f82e6 (feat)

TDD spike: failing tests committed first (RED), then implementation to pass (GREEN).

Files Created/Modified

• imptune/generators/intunewin_builder.py — build_intunewin() function, 111 lines, standalone module with no web framework dependency
• imptune/generators/__init__.py — generators package marker
• tests/test_intunewin.py — 14 byte-level tests organized into 4 test classes
• tests/__init__.py — tests package marker

Decisions Made

• IV is 16 bytes: STACK.md stated 32 bytes — this is a documentation error. AES block size is always 16 bytes. pycryptodome raises ValueError: IV must be 16 bytes long with 32-byte IV. Implementation uses os.urandom(16).
• MacKey is 32 bytes: svrooij articles do not specify exact MacKey size; chose 32 bytes (same as EncryptionKey) consistent with SvRooij.ContentPrep source behavior.
• Inner ZIP uses DEFLATE: Matches the C# reference implementation (.NET ZipArchive default). The conflicting "no compression" WebSearch result was treated as low-confidence (tertiary source); DEFLATE will be confirmed/corrected in the Phase 5 real Intune upload gate.
• Real Intune validation deferred: Pitfall 5 from RESEARCH.md is explicitly acknowledged — local byte-level tests confirm format structure, but the definitive validation requires a real Intune tenant upload in Phase 5.

Deviations from Plan

None - plan executed exactly as written.

Issues Encountered

None — all crypto operations succeeded on first implementation. pycryptodome correctly enforced 16-byte IV constraint (which would have caught the STACK.md documentation error if it had been used with 32 bytes).

User Setup Required

None — no external service configuration required. The .intunewin format validation against a real Intune tenant is a manual gate in Phase 5, not a configuration step.

Next Phase Readiness

• build_intunewin() is ready for use in Phase 5 (package export)
• Module is standalone — no dependency on FastAPI, SQLite, or any web framework
• Outstanding concern: byte-level format confidence is MEDIUM until a real Intune tenant upload confirms acceptance
• Blocker for Phase 5 only: access to a real Intune tenant for upload testing

---

Phase: 01-foundation Completed: 2026-04-10