decaflag

decaflag

A CLI tool that encodes strings into a table and indices format, with the ability to decode them back to the original message. The encoded data is stored in a JSON format and can be decoded back to the original message, which is then output in base64 format.

Installation

# Install globally
npm install -g decaflag

# Or run directly with npx
npx decaflag

Usage

Encoding a message

# Using global installation
decaflag "Hello, World!"

# Using npx
npx decaflag "Hello, World!"

This will create a data.json file containing the encoded message.

Decoding a message

# Using global installation
decaflag-decode

# Using npx
npx decaflag-decode

# Using npm script (alternative)
npm run decode

This will read the data.json file and create a flag file containing the decoded message in base64 format.

How it works

The tool works by creating a table of unique characters from the input string and storing their indices. This creates a simple form of encoding that can be easily reversed.

Data Format

The data.json file contains two main components:

• table: A string containing all unique characters from the input
• indices: An array of numbers representing positions in the table

Example:

Input:

npx decaflag "hello"

Generated data.json:

{
  "table": "helo\0",
  "indices": [0, 1, 2, 3, 3, 4]
}

When decoded, this will reconstruct "hello" and output it in base64 format.

More examples:

• Input: npx decaflag "Hello, World!"

  {
    "table": "Helo, Wrd!\0",
    "indices": [0, 1, 2, 2, 3, 4, 5, 6, 3, 7, 2, 8, 9]
  }
  

• Input: npx decaflag "AABBCC"

  {
    "table": "ABC\0",
    "indices": [0, 0, 1, 1, 2, 2]
  }
  

License

MIT License - See LICENSE file for details.