Add README

README.md

@@ -0,0 +1,76 @@
+# MagSec Encrypter
+
+A Windows desktop app for encrypting **text** and **image files** with authenticated, password-based encryption — wrapped in a polished, space-themed UI.
+
+![Platform](https://img.shields.io/badge/platform-Windows-0a7bdc)
+![.NET](https://img.shields.io/badge/.NET-10.0--windows-512bd4)
+![UI](https://img.shields.io/badge/UI-WinForms-2d4dde)
+
+## Features
+
+- **Text encryption** — encrypt/decrypt any text and copy the Base64 result to the clipboard.
+- **Image encryption** — encrypt image files (`.png`, `.jpg`, `.jpeg`, `.bmp`, `.gif`, `.webp`) into a `.mseimg` container and restore them later, with an in-app preview.
+- **Up to four access keys** — combine 1–4 keys into a single secret; the same combination is required to decrypt.
+- **Key tools** — generate a strong random key, toggle key visibility, and watch a live key-strength indicator.
+- **Drag & drop** — drop an image or a `.mseimg` file straight onto the window.
+
+## Security
+
+MagSec Encrypter uses modern, authenticated encryption from the .NET cryptography stack:
+
+| Aspect | Detail |
+| --- | --- |
+| Cipher | **AES-256-GCM** (authenticated encryption) |
+| Key derivation | **PBKDF2-HMAC-SHA512**, 600,000 iterations |
+| Salt | 16 bytes, random per operation |
+| Nonce | 12 bytes, random per operation |
+| Auth tag | 16 bytes |
+| Header integrity | The full header (format prefix, version, KDF parameters, salt, nonce) is bound into the GCM tag as **associated data**, so any tampering is detected on decrypt. |
+| Memory hygiene | Derived keys and secret bytes are zeroed (`CryptographicOperations.ZeroMemory`) after use. |
+| Key policy | A minimum combined key length is enforced to discourage weak secrets. |
+
+### Payload format
+
+Encrypted output is a self-describing **v2** binary payload (Base64-encoded for text):
+
+```
+prefix(4) | version(1) | kdfId(1) | iterations(4, big-endian) | salt(16) | nonce(12) | tag(16) | ciphertext
+```
+
+Storing the KDF parameters in the header provides **crypto agility** — the work factor or hash can change in future versions without breaking existing files. Legacy **v1** payloads (`TXT1` / `IMG1`) remain decryptable for backwards compatibility.
+
+> ⚠️ **There is no key recovery.** If you lose your key combination, the data cannot be decrypted. Store your keys somewhere safe.
+
+## Requirements
+
+- Windows
+- [.NET 10 SDK](https://dotnet.microsoft.com/download) (target framework `net10.0-windows`)
+
+## Build & run
+
+```bash
+dotnet build
+dotnet run
+```
+
+Or open the project in Visual Studio and press **F5**.
+
+## Usage
+
+1. Enter one or more **access keys** in the left rail (or click **Generate** for a strong random key).
+2. **Text:** type or paste into the Input box, then **Encrypt** / **Decrypt**. Use **Copy output** to grab the result.
+3. **Images:** **Open image** → **Encrypt image** to save a `.mseimg` file. To restore, **Open encrypted file** → **Decrypt image**.
+4. Use the **same key combination** for decryption that you used to encrypt.
+
+## Project layout
+
+| File | Purpose |
+| --- | --- |
+| `Form1.cs` | App logic, cryptography, custom controls, and the animated background |
+| `Form1.Designer.cs` | WinForms layout |
+| `Program.cs` | Entry point |
+| `TextEncryptorApp.csproj` | Project configuration |
+
+## License
+
+No license has been specified for this project.