RSA-OAEP Implementation Without Crypto Libraries

Justification

This project is an implementation of the RSA cryptographic algorithm with Optimal Asymmetric Encryption Padding (OAEP), built without using standard cryptography libraries. The main reasons for this development are:

1. Deep Understanding: Implementing the cryptographic algorithm from scratch allows a complete understanding of each step in the RSA-OAEP encryption and decryption process.

2. Full Control: With manual implementation, we have full control over the algorithm, enabling modifications and adjustments as needed.

3. Educational Value: This project serves as a learning tool to understand asymmetric cryptography concepts and secure padding techniques.

4. Transparency: Every step of the algorithm can be inspected and tested, providing full transparency on how the system works.

5. Use of OAEP: OAEP padding provides additional security compared to basic RSA implementations, protecting against various attacks such as Bleichenbacher's attack.

User Manual

1. Operating the GUI

Key Pair Generation

• Run the gui.py program, it will open a window with the Encrypt tab.
• Choose the Key Generation tab at the top left of the window.
• Select the file location to save your key pair (private and public key).
• Click the Generate Key Pair button, and the program will start generating the key pair.
• After successful creation, you can check your selected directory.

Encryption

Decryption

• Run the gui.py program, it will open a window with the Encrypt tab.
• Select your encrypted file by browsing through your computer directories.
• Choose your private key file from your computer.
• Click the Decrypt button, and it will display a success message once the decryption process is finished.
• Check your current directory for the successfully decrypted message.

2. Project Structure

TO BE ADJUSTED This project consists of several important files:

• rsa.py: Contains the core implementation of RSA and OAEP algorithms.
• key_pair_generation.py: CLI program for generating key pairs.
• keygen_cli.py: Alternative CLI for key generation.
• keygen_gui.py: Graphical interface for key generation.
• gui.py: Graphical interface for message encryption.
• encrypt_file.py: CLI program for encrypting files.
• decrypt_file.py: CLI program for decrypting files.

3. Technical Notes

• Implementation uses 2048-bit RSA keys.
• OAEP padding is applied using the SHA-256 hash function.
• Key formats are saved in hexadecimal representation with e:n or d:n format.
• Primality testing is implemented using the Miller-Rabin algorithm.
• Key generation may take some time as it involves finding large prime numbers.

5. Security

• Keep your private key safe and do not share it with others.
• For secure communication, only share your public key with parties who want to send encrypted files.
• This implementation is intended for educational purposes; for production use, it is recommended to use well-tested and audited cryptographic libraries.

6. Constraints

• The size of files that can be encrypted is limited by the RSA key size.
• The current encryption GUI supports TO BE ADJUSTED, TO BE ADJUSTED, TO BE ADJUSTED.

System Requirements

• Python 3.6 or later
• Tkinter for the graphical interface
• No external cryptographic libraries required