How It Works

1. User Setup

• Connect the HID keyboard.
• Input the custom SHA-256 interruption vector (not stored, only used in RAM).
• Configure the destination IP and port of the target device.

2. Sending a Message

• The system encrypts the message using SHA-256 hashing with the user-defined vector.
• The encrypted message is sent via Ethernet using the W5500 module.

3. Receiving & Decryption

• The recipient device receives the encrypted message.
• If the same interruption vector is manually entered, the message is decrypted successfully.
• If the incorrect vector is used, the message remains unreadable.

Why is it Impossible to Decrypt?

• No stored encryption keys: Each session requires a manually entered vector, meaning even if a device is captured, past messages cannot be retrieved.
• Custom communication protocol: Without knowing the exact system architecture, attackers cannot decipher the encryption method or data structure.
• SHA-256 strength: Even with brute force, SHA-256 remains computationally infeasible to break.

Conclusion

This project is perfect for individuals or organizations needing absolute privacy in communications. Whether for personal security, journalistic protection, or sensitive military applications, our STM32F103-based system ensures that messages remain confidential and beyond the reach of any third-party eavesdropping.