Hybrid Encryption System

A Python-based encryption system that combines RSA and AES encryption algorithms to provide secure message encryption. This hybrid approach leverages the strengths of both symmetric (AES) and asymmetric (RSA) encryption.

🔐 How It Works

The system uses a hybrid encryption approach:

1. Message Encryption: Your message is encrypted using AES-256-ECB
2. Key Protection: The AES key is encrypted using RSA-2048
3. Storage: Both encrypted message and encrypted AES key are saved securely

This approach combines:

• AES: Fast symmetric encryption for large messages
• RSA: Secure asymmetric encryption for key exchange

🚀 Features

• Hybrid Encryption: RSA + AES encryption for optimal security and performance
• Key Management: Automatic RSA key pair generation and secure storage
• Multiple Encryption Modes:
  • Hybrid encryption (RSA + AES)
  • AES-only encryption
  • RSA-only encryption
• Secure Decryption: Complete decryption system with error handling
• File Management: Encrypted data saved in JSON format
• User-Friendly Interface: Interactive command-line interface

📋 Requirements

pip install rsa cryptography

Dependencies

• rsa: RSA encryption/decryption
• cryptography: AES encryption and cryptographic primitives
• pickle: Key serialization
• json: Data storage format

🛠️ Installation

1. Clone or download the project files
2. Install required dependencies:

   pip install rsa cryptography

3. Run the encryption system:

   python encrypt.py

📖 Usage

Encryption (encrypt.py)

Run the encryption script:

python encrypt.py

Available Options:

1. Generate new keys and encrypt - Creates new RSA key pair and encrypts your message
2. Use existing keys to encrypt - Uses previously generated keys for encryption
3. AES-only encryption - Encrypts using only AES-256
4. RSA-only encryption - Encrypts using only RSA (limited message size)
5. Exit - Quit the program

Decryption (decrypt.py)

Run the decryption script:

python decrypt.py

Available Options:

1. Decrypt hybrid encrypted message - Decrypts RSA + AES encrypted data
2. Decrypt AES-only encrypted message - Decrypts AES-only data
3. Decrypt RSA-only encrypted message - Decrypts RSA-only data
4. Decrypt custom hybrid data - Specify custom file paths for decryption
5. List available encrypted files - Show all available encrypted files
6. Exit - Quit the program

📁 File Structure

After running the encryption system, the following files will be created:

├── encrypt.py              # Main encryption script
├── decrypt.py              # Main decryption script
├── keys/                   # Directory for RSA keys
│   ├── private_key.pkl     # RSA private key (keep secret!)
│   └── public_key.pkl      # RSA public key
├── encrypted_data.json     # Hybrid encrypted data
├── aes_encrypted.json      # AES-only encrypted data (if used)
└── rsa_encrypted.json      # RSA-only encrypted data (if used)

🔑 Key Management

RSA Keys

• Key Size: 2048-bit RSA keys
• Storage: Keys are saved as pickle files in the keys/ directory
• Security: Keep your private key (private_key.pkl) secure and secret

AES Keys

• Key Size: 256-bit AES keys
• Generation: Randomly generated for each encryption
• Protection: AES keys are encrypted with RSA before storage

📄 Data Format

Hybrid Encrypted Data (encrypted_data.json)

{
    "encrypted_message": "hex_encoded_aes_encrypted_message",
    "encrypted_aes_key": "hex_encoded_rsa_encrypted_aes_key",
    "encryption_method": "AES-256-ECB + RSA-2048",
    "timestamp": "encryption_timestamp"
}

🔒 Security Features

• RSA-2048: Industry-standard asymmetric encryption
• AES-256: Advanced symmetric encryption
• PKCS7 Padding: Proper message padding for AES
• Secure Key Generation: Cryptographically secure random key generation
• Key Separation: AES keys are never stored in plaintext

⚠️ Important Notes

1. Keep Private Keys Safe: Never share your private key file
2. Backup Keys: Store copies of your keys in a secure location
3. Message Size Limits: RSA-only mode has message size limitations
4. Key Dependencies: You need the private key to decrypt any encrypted data

🎯 Example Workflow

1. First Time Setup:

   python encrypt.py
   # Choose option 1 to generate new keys
   # Enter your message
   # Keys and encrypted data are saved

2. Decrypt Your Message:

   python decrypt.py
   # Choose option 1 for hybrid decryption
   # Your original message is recovered

3. Subsequent Encryptions:

   python encrypt.py
   # Choose option 2 to use existing keys
   # Enter new message to encrypt

🛡️ Security Considerations

• This implementation uses ECB mode for AES, which is suitable for demonstration but consider CBC/GCM for production
• Store private keys in secure locations
• Consider implementing additional authentication mechanisms for production use
• Regular key rotation is recommended for high-security applications

🤝 Contributing

Feel free to contribute improvements, bug fixes, or additional features to this hybrid encryption system.

📜 License

This project is provided as-is for educational and development purposes.