LockNote

A single .exe that is both a text editor and an encrypted vault. Your notes are stored inside the executable itself — no config files, no temp files, no installation, no dependencies.

 ┌─────────────────────────────────────────┐
 │            LockNote.exe                 │
 │  ┌───────────────┬───────────────────┐  │
 │  │   Program     │  Encrypted data   │  │
 │  │   (Rust)      │  (AES-256-CBC)    │  │
 │  └───────────────┴───────────────────┘  │
 └─────────────────────────────────────────┘
        One file. Zero footprint.

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The problem

You need to store sensitive text (passwords, keys, private notes) on a USB stick, a shared PC, or a network drive. Traditional note apps leave cleartext files on disk. Password managers require installation. Cloud solutions require connectivity and trust.

The solution

LockNote is a self-contained encrypted notepad. Copy a single .exe anywhere — USB drive, desktop, network share — and your encrypted notes travel with it. Nothing is ever written to disk in cleartext.

What you type	What's on disk	What an attacker sees
my secret API key: sk-1234	AES-256 ciphertext	Random bytes

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Quick start

Download

Grab LockNote.exe from the latest release — a single portable file, ready to use.

Build from source

Requires Rust (stable, x86_64-pc-windows-gnu target):

scripts\build.cmd

Output: build\LockNote.exe

First launch

1. Create a password (entry + confirmation, with strength indicator)
2. Type your notes in the editor
3. Ctrl+S to encrypt and save — data is written inside the .exe itself

Subsequent launches

1. Enter your password (5 attempts max)
2. Edit your notes
3. Ctrl+S to re-encrypt with fresh salt and IV

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Features

Editor

• Find (Ctrl+F) and Find & Replace (Ctrl+H) popups with Previous/Next navigation, live match counter (3 / 12), match case, whole word
• Go to line (Ctrl+G)
• Undo / redo (Ctrl+Z / Ctrl+Y)
• Line numbers gutter (auto-adjusting width)
• Insert timestamp (F5 — inserts yyyy-MM-dd HH:mm)
• Duplicate line (Ctrl+D) and delete line (Ctrl+Shift+K)
• Word, character, and line count in status bar
• Cut / Copy / Paste / Paste plain text (Ctrl+Shift+V)
• Right-click context menu with clipboard operations
• Select all (Ctrl+A)

Security

• AES-256-CBC encryption with HMAC-SHA256 authentication
• Argon2id key derivation (64 MiB memory cost, tunable)
• Password strength indicator on creation
• 5 unlock attempts max (brute-force protection)
• Zero cleartext on disk — ever
• All sensitive buffers zeroed after use

Settings

• Dark / light theme with system-aware defaults
• Save-on-close behavior: Ask / Always / Never
• Configurable font family and size
• Minimize to system tray
• Always on top (View menu toggle)
• Auto-update check via GitHub releases

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Keyboard shortcuts

Shortcut	Action
Ctrl+S	Save (encrypt & write)
Ctrl+F	Find (popup)
Ctrl+H	Find & Replace (popup)
Ctrl+G	Go to line
Ctrl+Z / Ctrl+Y	Undo / Redo
Ctrl+D	Duplicate current line
Ctrl+A	Select all
Ctrl+Q	Quit
Ctrl+Shift+V	Paste as plain text
Ctrl+Shift+K	Delete current line
F5	Insert timestamp
Enter (in Find popup)	Find next

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How it works

Self-modifying executable

LockNote appends encrypted data after a binary marker at the end of its own .exe. Since Windows locks a running executable, saves go through an atomic swap mechanism.

┌──────────────────────┬────────┬──────────────────────────────┐
│   Rust PE executable │ Marker │  [salt][iv][hmac][ciphertext] │
│                      │(16 B)  │        (variable)            │
└──────────────────────┴────────┴──────────────────────────────┘

Cryptography

Component	Detail
Cipher	AES-256-CBC (PKCS7 padding)
Authentication	HMAC-SHA256 (encrypt-then-MAC)
Key derivation	Argon2id (m_cost 64 MiB, t_cost 3, 4 lanes)
Salt	16 bytes, random per save
IV	16 bytes, random per save
KDF params stored	m_cost, t_cost, p_lanes (12 bytes, allows cost bump without format change)
Key material	64 bytes (32 enc + 32 mac) from a single Argon2id call
Verification	HMAC checked before decryption (constant-time comparison)

Wire format: [salt 16B][IV 16B][argon2 params 12B][HMAC 32B][ciphertext]

Security properties

• Zero cleartext on disk — no temp files, no swap, no config
• Fresh randomness — salt and IV regenerated on every save
• Encrypt-then-MAC — ciphertext integrity verified before decryption
• Constant-time comparison — HMAC check is not vulnerable to timing attacks
• Buffer cleanup — all sensitive byte arrays zeroed after use
• Brute-force protection — 5 password attempts max, then the program exits

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Architecture

src/
├── main.rs                     Entry point, panic handling
├── crypto/mod.rs               AES-256-CBC + HMAC-SHA256, Argon2id
├── storage/mod.rs              Binary marker, read/write encrypted payload
├── settings/mod.rs             User settings (theme, save-on-close)
├── theme/mod.rs                Dark/light theme system
├── updater.rs                  Auto-update check via GitHub releases
├── integration_tests.rs        Integration tests
├── ui/
│   ├── mod.rs                  UI entry point, password flow
│   ├── editor.rs               Editor, menus, shortcuts, status bar
│   └── dialogs/
│       ├── create_password.rs  Password creation dialog
│       ├── unlock.rs           Password prompt (5 attempts max)
│       ├── close_confirm.rs    Save-on-close confirmation
│       ├── goto_line.rs        Go-to-line dialog
│       ├── find_replace.rs     Find / Find & Replace popup
│       ├── settings_dialog.rs  Settings UI
│       ├── preferences_dialog.rs  User preferences (font, behavior)
│       ├── security_dialog.rs  Security settings (password change)
│       └── about.rs            About dialog

Built with Rust using native-windows-gui for the native Windows UI, and pure Rust cryptography crates (aes, cbc, hmac, sha2, pbkdf2).

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Testing

cargo test

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Requirements

Component	Requirement
OS	Windows 10 or 11 (x64)
Runtime	None — native Rust executable
Build	Rust stable (x86_64-pc-windows-gnu)
Dependencies	None at runtime

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LockNote Pro

Looking for more features? LockNote Pro adds:

Category	Features
Editor	Multi-tab notes with color labels, Markdown preview (split or full)
Security	Auto-lock after inactivity, clipboard auto-clear, TOTP two-factor authentication, duress password (decoy content under coercion)
Vault	Built-in encrypted password & secrets manager with categories, reveal-on-click, copy with auto-clear
Attachments	Embed encrypted files (images, PDFs, documents) inside the executable
Steganography	Hide your encrypted notes inside a normal-looking image (JPEG, PNG, BMP)
QR code export	Transfer encrypted notes to your phone via QR code — no network needed
Snapshots	Named version history with instant restore
Localization	English, French, Spanish, German
Productivity	Auto-save, GZip compression, global hotkey (Ctrl+Shift+L), import/export text files

Get LockNote Pro

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Contributing

1. Fork the repo
2. Create a feature branch
3. Make sure scripts\build.cmd and cargo test pass
4. Open a Pull Request

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License

Custom License — Created by UITGuard

• Personal use: Free to use, modify, and redistribute
• Commercial / Enterprise use: Paid license required — contact [email protected]