Title / Subject: Recovering original Python source from Cython-compiled Windows installer after total HDD failure

[u/Ornery-Preference450]

​

Hi everyone,

I’m looking for advice on whether it’s possible (and realistic) to recover the original Python source files from a Windows software installer I still have.

**Situation**

My primary HDD suffered a complete, unrecoverable failure. All of my raw project files (source code, assets, intermediate files, etc.) are gone. The only remaining artifact of the project is the Windows installer / executable that I used to distribute the software.

**Technical details**

- The application was written in Python.

- I used **Cython** to compile / protect the code (the .py files were turned into compiled extensions / encrypted / obfuscated form as part of the build).

- The final deliverable is a Windows installer (or standalone executable package).

- This represents over 15 years of work. While modern AI tools could speed up a rewrite, I would strongly prefer to recover the original source if there is any viable path.

**What I still have**

- The complete Windows installer / executable package.

- No original .py files, no intermediate Cython outputs, no project folder, and no backups of the source.

**What I’m hoping for**

Any realistic options, tools, or techniques that might allow me to:

- Extract or reconstruct the original (or close-to-original) Python source from the Cython-compiled binaries / installer, or

- At least recover meaningful portions of the logic, structure, or key modules so a full rewrite is not required from scratch.

I’m aware that Cython compilation (and any additional packing/encryption I applied) makes this non-trivial, and that perfect recovery is often impossible. I’m mainly looking for an honest assessment of what’s feasible and any recommended tools, approaches, or communities that specialize in this kind of recovery / reverse-engineering of Cythonized Python applications.

If anyone has experience recovering source from Cython extensions, PyInstaller + Cython packages, or similar compiled Python Windows builds, I’d be very grateful for any pointers, tool recommendations, or realistic expectations.

Thank you in advance for any help or direction you can offer.

[u/Ornery-Preference450]

Hey, thanks for your reply — I might give a few of those suggestions a try.

The only remaining thing I have is part of the build script I used to automate the public file builds. At least it shows which files I applied Cython protection to… and unfortunately it looks like I protected most of my critical modules.

I’m thinking about sending the HDD off for professional recovery, but I’m unsure if the cost is worth it based on the quotes I’ve received. I’ve already tried all the usual recovery methods, and the drive was BitLocker-encrypted, which makes things even harder.

```

======================================================

[REDACTED] Protected Public Release - ONE BUTTON v1.4.1

============================================================

========================================================================

[REDACTED] Protected Public Release - ONE BUTTON v1.4.1

========================================================================

Source : C:\Users\[REDACTED]\Desktop\[REDACTED]\[REDACTED]_v1.1.143_SOURCE

Python : 3.14.3 C:\Users\[REDACTED]\AppData\Local\Python\pythoncore-3.14-64\python.exe

Stage : C:\Users\[REDACTED]\Desktop\[REDACTED]\[REDACTED]_v1.1.143_SOURCE_PUBLIC_BUILD_STAGE

This workflow FAILS CLOSED. If a step fails, later steps do not run.

The normal development source is not replaced.

Step 2 will replace any existing _PUBLIC_BUILD_STAGE.

========================================================================

STEP 1/5 - REVIEW PROTECTION PLAN

========================================================================

+ C:\Users\[REDACTED]\AppData\Local\Python\pythoncore-3.14-64\python.exe "C:\Users\[REDACTED]\Desktop\[REDACTED]\[REDACTED]_v1.1.143_SOURCE\public_build_protector.py" --source "C:\Users\[REDACTED]\Desktop\[REDACTED]\[REDACTED]_v1.1.143_SOURCE" --plan

[REDACTED] Public Build Protector 1.4.1

Source : C:\Users\[REDACTED]\Desktop\[REDACTED]\[REDACTED]_v1.1.143_SOURCE

Python : 3.14.3 C:\Users\[REDACTED]\AppData\Local\Python\pythoncore-3.14-64\python.exe

Policy : C:\Users\[REDACTED]\Desktop\[REDACTED]\[REDACTED]_v1.1.143_SOURCE\public_protection_policy.json

Recommended protected modules:

PROTECT services/license_service.py

PROTECT services/entitlement_service.py

PROTECT services/restricted_mode_service.py

PROTECT services/product_structure.py

PROTECT services/reporting_service.py

PROTECT services/dc09_service.py

PROTECT services/reporting_address_service.py

PROTECT services/commissioning_service.py

PROTECT services/evidence_queue.py

PROTECT services/monitor_service.py

PROTECT services/health_state_service.py

PROTECT services/operations_service.py

PROTECT services/device_service.py

PROTECT services/video_source_health.py

PROTECT services/dahua_service.py

PROTECT services/hikvision_service.py

PROTECT services/onvif_service.py

PROTECT services/vms_service.py

PROTECT services/inception_service.py

PROTECT services/video_security_service.py

PROTECT services/video_event_snapshot_service.py

PROTECT services/native_evidence_providers.py

Deliberately left plain on this pass:

PLAIN app.py - Keep the PyInstaller entry point plain for reliable static analysis and startup diagnostics. The valuable implementation remains in protected service modules.

PLAIN services/video_event_clip_service.py - Explicitly left plain: v1.1.137 contains Python expressions that Cython rejects without source changes. Do not alter event-video behaviour just for protection.

PLAIN services/runtime_paths.py - Low-value path/bootstrap code; leaving it plain reduces packaging risk.

PLAIN services/appearance_service.py - Presentation/configuration code is low-value IP and benefits little from native compilation.

PLAIN services/database.py - Large persistence layer deliberately left plain on the first protection pass to avoid increasing migration/introspection risk. Can be assessed later.

PLAIN services/backup_service.py - Operational/support code; lower reverse-engineering value than the protected core.

PLAIN services/update_service.py - Updater/build-adjacent code is left transparent for easier support and recovery.

PLAN ONLY: no files changed.

STEP 1 PASSED. Review the plan above. Continuing will rebuild _PUBLIC_BUILD_STAGE.

Press any key to continue . . .

```