Code shared from the Rust Playground

playground.rs

use std::fs::File;
use std::io::Write;

/// Replicates the 'Highlight' steganography style.
/// Data is hidden in the filter coefficients rather than coordinates.
pub struct HighlightStego {
    pub color: String, // #A112ED
}

impl HighlightStego {
    pub fn generate_svg(&self, output_path: &str, payload: &[u8]) -> std::io::Result<()> {
        let mut svg = format!(
            "<svg width='512' height='512' viewBox='0 0 100 100' xmlns='http://www.w3.org/2000/svg'>\n\
            <defs>\n\
            <filter id='stegoFilter'>\n"
        );

        // iOS-style encoding: The payload is hidden in the 'values' matrix.
        // We use the matrix to 'highlight' the image, but the coefficients are our data.
        let mut matrix_values = String::new();
        for &byte in payload.iter().take(20) {
            // Normalize byte to a float (0.000 to 0.255) for the matrix
            matrix_values.push_str(&format!("{:.3} ", byte as f32 / 1000.0));
        }
        
        // Fill remaining matrix slots if payload is short
        while matrix_values.split_whitespace().count() < 20 {
            matrix_values.push_str("0 ");
        }

        svg.push_str(&format!(
            "  <feColorMatrix type='matrix' values='{}' />\n",
            matrix_values.trim()
        ));
        
        svg.push_str(
            "</filter>\n\
            </defs>\n"
        );

        // Drawing the Git Logo with the filter applied
        svg.push_str(&format!(
            "  <rect x='14.6' y='14.6' width='70.8' height='70.8' rx='10' fill='{}' transform='rotate(45 50 50)' filter='url(#stegoFilter)' />\n",
            self.color
        ));
        
        svg.push_str("  <path d='M45 25 L45 75 M45 50 L70 50' stroke='white' stroke-width='6' stroke-linecap='round' />\n");
        svg.push_str("  <circle cx='45' cy='25' r='8' fill='white' />\n");
        svg.push_str("  <circle cx='45' cy='75' r='8' fill='white' />\n");
        svg.push_str("  <circle cx='70' cy='50' r='8' fill='white' />\n");
        svg.push_str("</svg>");

        let mut file = File::create(output_path)?;
        file.write_all(svg.as_bytes())?;
        Ok(())
    }
}

fn main() -> std::io::Result<()> {
    let stego = HighlightStego { color: "#A112ED".to_string() };
    // Encoding 'BIP-64MOD' into the color matrix
    stego.generate_svg("ios_style_carrier.svg", b"BIP-64MOD")?;
    
    println!("iOS Highlight Style Carrier generated.");
    println!("Data is embedded in the <feColorMatrix> coefficients.");
    Ok(())
}