App Personal — open source

The Crypt-in Personal Windows app is open source under GPL-3.0. You can build it, fork it, contribute to it, or port it to Linux and macOS.

Licence: GPL-3.0  |  Binary: /beta/

The SDK it uses is Apache-2.0, which is compatible with GPL v3 — that compatibility is why the app is v3 and not v2. See Licence.

Source: github.com/lake8dev/cryptin-sdk — the repository opens at the developer beta, 30 September 2026. It does not exist yet, which is why the link is not clickable.

What the app does

• Detects the Crypt-in dongle over USB HID
• Authenticates with the PIN
• Encrypts files to .crin by drag and drop
• Decrypts .crin files
• Guides the first-boot backup of seed and PIN
• Activates the licence against the licence server

What the app does not do

• It contains no cryptographic keys
• It sends no secrets to lake8.dev
• It cannot decrypt anything without the dongle

That last point is the one worth testing yourself: unplug the dongle and the app becomes a file browser that opens nothing.

Build from source

git clone https://github.com/lake8dev/cryptin-sdk
cd cryptin-sdk/app-personal

# Requirements: Visual Studio 2022, .NET 8
dotnet build
dotnet run

Architecture

App Personal
├── UI layer (WinForms)
│   ├── MainForm      — drag and drop
│   ├── PinForm       — PIN entry
│   └── SetupWizard   — first boot, seed and PIN backup
│
├── Dongle layer
│   ├── HidConnection — USB HID transport
│   └── PinAuth       — VERIFY_PIN and state handling
│
├── Crypto layer
│   ├── CrinFormat    — .crin read and write
│   └── AesGcm        — AES-256-GCM, keys derived per file
│
└── Licence layer
    └── LicenceClient — activation and transfer

The crypto layer never holds a long-lived key: it derives the per-file key from the dongle secret and a per-file salt, uses it, and drops it.

Contributing

1. Fork the repository
2. Create a branch
3. Open a PR against contrib
4. CI runs automatically
5. Review by the community or by lake8.dev
6. If approved, merged to main
7. lake8.dev signs the release binary

lake8.dev always reviews any change to the crypto layer, the licence layer or the HID protocol.

The community can review UI and UX work, bug fixes with tests, platform ports, and documentation.

The firmware is never part of this repository: it stays closed source and is distributed only as a signed binary. See the open source policy.

Porting to Linux or macOS

The dongle layer uses hidapi, which is cross-platform. The UI layer is WinForms and needs replacing — Avalonia or GTK# on Linux, MAUI on macOS.

If you port it, open a PR: lake8.dev will review and merge.

Support

Questions: info@lake8.dev · Security: security@lake8.dev