Emoji Encoder/Decoder A Rust command-line tool for hiding and retrieving secret messages by encoding them into emoji sequences using Unicode variation selectors.

Overview This project demonstrates a simple steganography technique where secret messages are hidden in plain sight by encoding them within emoji strings. Each message is encoded using a base emoji combined with variation selectors to represent bits of the message. An improved encoding scheme is used here to pack 4 bits (a nibble) per emoji pair by utilizing Unicode variation selectors U+FE00 through U+FE0F.

For example, the message "Hello" is encoded into a sequence of emoji pairs. When decoded, the program retrieves the original message.

Encoding Scheme Encoding: For each byte of the input message, split the byte into two 4-bit nibbles. Each nibble is then encoded as:

A base emoji (default is 😀, but this can be changed) A variation selector from U+FE00 (representing 0) to U+FE0F (representing 15) This means each byte becomes 2 emoji pairs (4 Unicode characters), making the overall encoding more efficient than one bit per emoji pair.

Decoding: The program extracts the variation selectors from the emoji string, reassembles the nibbles into bytes, and converts them back to the original text.

Prerequisites Rust – Install via rustup. Installation Clone the Repository (or create a new project):

bash Copy git clone https://github.com/yourusername/emoji_encoder.git cd emoji_encoder Or create a new Cargo project:

bash Copy cargo new emoji_encoder cd emoji_encoder Replace the Contents of src/main.rs:

Copy and paste the provided Rust code (the improved version) into src/main.rs.

Usage Build the Project Compile the project using Cargo:

bash Copy cargo build --release Running the Program The program supports two commands: encode and decode.

Encode a Message To encode a message, use:

bash Copy cargo run -- encode "Your secret message" "😀" Example:

bash Copy cargo run -- encode "Hello" "😀" This will output an encoded string consisting of emoji and variation selectors.

Decode a Message To decode an encoded string, use:

bash Copy cargo run -- decode "<your_encoded_string_here>" Example:

Suppose you have the following encoded string:

Copy 😀︃😀︊😀︂😀︈ Run:

bash Copy cargo run -- decode "😀︃😀︊😀︂😀︈" This should print the original secret message (e.g., :().

Example Encoding "Hello":

bash Copy cargo run -- encode "Hello" Output might be (using the improved nibble method):

Copy 😀︄😀︈😀︆😀︅😀︆😀︌😀︆😀︌😀︆😀︎ Decoding the above output:

bash Copy cargo run -- decode "😀︄😀︈😀︆😀︅😀︆😀︌😀︆😀︌😀︆😀︎" The program should output:

nginx Copy Hello Improvements Efficiency: The improved scheme encodes 4 bits per emoji pair by using the full range of variation selectors (U+FE00 to U+FE0F). This reduces the character overhead compared to encoding one bit per pair.

Customization: You can easily change the base emoji by providing a different emoji as the third command-line argument when encoding.

Error Handling: The program checks for incomplete sequences or invalid variation selectors during decoding and reports errors accordingly.

Contributing Feel free to fork this repository and submit pull requests with improvements or bug fixes. Contributions that enhance the efficiency or functionality of the encoding/decoding process are welcome.

License This project is licensed under the MIT License.

This README should provide a solid starting point for users to build, run, and understand the project. Enjoy encoding your secret messages!