SC2 RSA Signature Verification

This project provides a custom implementation of RSA signature verification in SC2, enabling secure message validation through RSA signatures. RSA signatures work by encrypting a hash of the message with a private key, allowing the recipient to verify its authenticity by decrypting it with the corresponding public key.

The project includes:

• BigNum Library: An arbitrary-precision arithmetic library (specifically written for SC2) to handle large integers beyond the 32-bit limit.

• SHA1 Library: A hashing library (also specifically tailored for SC2) to provide the necessary functionality for message hashing in RSA signature verification.

• Python Signing Tool: Generates RSA key pairs, signs messages, and outputs a Base64-encoded string for use in SC2.

Table of Contents

• Installation
• Usage
• Example
• License

Installation

1. Clone the repository:

   git clone https://github.com/R-P-S/SC2-RSA.git
   cd SC2-RSA
   

2. Requirements:

   • Python 3

     If Python is not installed, download and install it here.

3. Install Required Python Package

    pip install https://github.com/R-P-S/SC2-RSA/archive/master.zip
   

   This command installs all necessary Python dependencies for the signing tool.

Usage

1. Initial Run of the Python Signing Tool

   $ sc2signer
   

   The tool will guide you through the setup. On the first run, you’ll be asked to select an RSA key size:

   • Select 1024 or 2048 bits. A 1024-bit key is recommended for optimal performance. If you're using a 2048-bit key, set the constant KEY_SIZE_MULTIPLIER to 2 in bignum.galaxy or in the trigger library if using the GUI.

     Once keys are generated, the script saves them to a .pem file and copies the public key to your clipboard. Paste this key into the PUBLIC_KEY constant in rsa.galaxy or, if using the GUI, into the PUBLIC_KEY constant in the trigger module.

2. Signing Messages with the Python Script

   • Enter a message and player ID (X-S2-X-XXXXXXX) when prompted.
   • The script will ask how many days the signed message should remain valid. If you provide a number of days (e.g., 7), the tool calculates a Unix timestamp for expiration. It embeds that timestamp in the signed message. If you enter 0 for days, there is no expiration attached to the signature.
   • The script outputs a signed message in Base64 format.

3. Verifying Signatures in SC2

   Once a signed message is generated, it can be verified in-game. The included example trigger gt_DecryptSignature listens for the chat command (e.g., -m {signed_message}) and verifies the signature by:

   • Decrypting the RSA signature.
   • Comparing it with the expected hash.

4. Key File Location

   The RSA key pair is stored in a user-specific directory. Make sure to keep this file secure, as it contains the private key used for signing.

   • Windows: C:\Users\<Username>\AppData\Local\SC2Signer\rsa_keys.pem
   • macOS: /Users/<Username>/Library/Application Support/SC2Signer/rsa_keys.pem
   • Linux: /home/<Username>/.local/share/SC2Signer/rsa_keys.pem

Example

Python Signing Tool

Example run:

$ sc2signer
Write message: Marine 5
Enter Player Profile ID: SC2E-TEST-ACCOUNT
How many days should the signed message be valid? (0 for no time limit): 0

Verification

In Starcraft 2's chat console:

-m {signed_message}

License

This project is licensed under the MIT License. See the LICENSE file for more details.