Show HN: An encrypted, local, cross-platform journaling app

Mini Diarium is a new encrypted, local-only journaling app

Mini Diarium is a new cross-platform journaling app that keeps all your entries encrypted and stored locally on your machine. The app, built with Tauri 2, SolidJS, and Rust, is a modern rebuild of the unmaintained app Mini Diary.

Developer Francisco J. Revoredo created it as a spiritual successor, preserving the original's core philosophy of being encrypted, local-only, and minimal. The new version is lighter and faster with stronger encryption.

Key file authentication replaces passwords

Mini Diarium's standout feature is its key file authentication system. Instead of just a password, you can unlock your diary with an X25519 private key file, similar to using an SSH key.

You can register multiple key files and manage all authentication methods from the Preferences. This allows for several practical scenarios:

• Using a .key file on a USB drive as a physical second factor
• Storing the key file in a password manager as a secure attachment
• Registering one key file per machine for easy access revocation
• Sharing an account with separate keys under different labels

The private key never enters the database, and the stored public key cannot unlock the diary. A wrong or tampered key file is rejected by AES-GCM authentication.

Strong encryption and local-only architecture

Every entry is encrypted with AES-256-GCM before touching disk. The app uses a wrapped master key design where each authentication method holds its own encrypted copy of a random master key.

This means adding or removing an authentication method is an O(1) operation with no re-encryption of your entries. The master key is never stored in plaintext.

The app has zero network access—no telemetry, analytics, or update checks. Everything runs locally, with the UI communicating with the Rust backend via Tauri invoke() and the backend reading and writing to local SQLite.

Import, export, and cross-platform support

Mini Diarium supports importing from several formats with merge conflict resolution. You can import from:

• Mini Diary JSON
• Day One JSON/TXT
• jrnl JSON

Export options include JSON and Markdown formats. The app also features automatic backups with rotation, a rich text editor, calendar navigation, themes, and statistics.

It's available for Windows, macOS, and Linux. Since it's an unsigned application, Windows SmartScreen may show a warning on first launch—you'll need to click "More info" then "Run anyway." On macOS, you may need to right-click the app icon and select "Open" to bypass Gatekeeper.

Quick start and keyboard shortcuts

To get started, launch Mini Diarium and create a password (there is no recovery if forgotten). Write your first entry—it auto-saves as you type. Navigate between days with keyboard shortcuts or by clicking dates on the calendar.

Key shortcuts include:

• Previous Day: Ctrl+Left (Cmd on macOS)
• Next Day: Ctrl+Right (Cmd on macOS)
• Go to Today: Ctrl+T (Cmd on macOS)
• Preferences: Ctrl+, (Cmd on macOS)
• Import: Ctrl+Shift+I (Cmd on macOS)
• Export: Ctrl+Shift+E (Cmd on macOS)

Lock your diary when you're done. The app is open source, and builds are reproducible from source. For security, you can verify the SHA256 checksum against checksums-linux.txt from the release before installation.