Cryptography — AES-256-GCM File Encryptor

CLI tool for encrypting and decrypting files using AES-256-GCM with password-derived keys (PBKDF2 + SHA-256).

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Features

• AES-256-GCM authenticated encryption — detects tampering automatically
• PBKDF2 key derivation with 200,000 iterations — brute-force resistant
• Random salt + nonce per encryption — same file + password = different output every time
• Simple CLI interface — encrypt and decrypt commands
• Works on any file type (text, binary, images, archives)

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Encrypted File Format

``` [MAGIC 4B][VERSION 1B][SALT 16B][NONCE 12B][TAG 16B][CIPHERTEXT ...] ```

The header embeds all parameters needed for decryption — no separate metadata file required.

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Quick Start

```bash pip install -r requirements.txt python -m cryptor.cli encrypt secret.txt -o secret.txt.enc python -m cryptor.cli decrypt secret.txt.enc -o secret.txt ```

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Project Structure

``` Cryptography/ ├── cryptor/ │ ├── crypto.py # AES-256-GCM core logic │ ├── cli.py # CLI interface (argparse) │ └── utils.py # Password prompt, path helpers ├── tests/ │ ├── test_crypto.py │ └── test_cli.py └── .github/workflows/ci.yml ```

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Running Tests

```bash pytest tests/ -v

7 passed

```

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Security Notes

Property	Implementation
Cipher	AES-256-GCM (authenticated)
Key derivation	PBKDF2-SHA256, 200,000 iterations
Salt	16 bytes, random per encryption
Nonce	12 bytes, random per encryption
Authentication tag	16 bytes, verified before decryption

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Requirements

``` pycryptodome>=3.20.0 pytest>=8.0.0 ```

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Author

Astrahan45 — Network Engineer · MSc Integrated Communications Systems