steganography in base64 images

base64-steganography.js

const PNG = require('pngjs').PNG
const fs = require('fs')

// Function to embed text into a base64 encoded PNG
function embedTextInBase64PNG(base64Image, text) {
    let data = Buffer.from(base64Image, 'base64')
    let png = PNG.sync.read(data)
    let textBinary = (text + '\0').split('').map(char => char.charCodeAt(0).toString(2).padStart(8, '0')).join('')
    let dataIndex = 0

    for (let i = 0; i < png.data.length && dataIndex < textBinary.length; i += 4) {
        for (let bit = 0; bit < 3 && dataIndex < textBinary.length; bit++, dataIndex++) {
            png.data[i + bit] = (png.data[i + bit] & 0xFE) | parseInt(textBinary[dataIndex])
        }
    }

    let buffer = PNG.sync.write(png)
    return buffer.toString('base64')
}

// Function to extract text from a base64 encoded PNG
function extractTextFromBase64PNG(base64Image) {
    let data = Buffer.from(base64Image, 'base64')
    let png = PNG.sync.read(data)
    let binaryMessage = []
    let text = ''

    for (let i = 0; i < png.data.length; i += 4) {
        for (let bit = 0; bit < 3; bit++) {
            binaryMessage.push(png.data[i + bit] & 0x01)
        }
    }

    console.log("Total binary length: " + binaryMessage.length);

    for (let i = 0; i < binaryMessage.length; i += 8) {
        let byte = binaryMessage.slice(i, i + 8).join('')
        let charCode = parseInt(byte, 2)
        if (charCode === 0) {
            break; // Stop at the null character
        }
        text += String.fromCharCode(charCode)
    }

    return text;
}


// Example usage
let originalImageBase64 = fs.readFileSync('input.png', { encoding: 'base64' })
let embeddedImageBase64 = embedTextInBase64PNG(originalImageBase64, 'Hidden message!')
fs.writeFileSync('output.png', embeddedImageBase64, { encoding: 'base64' })

let extractedMessage = extractTextFromBase64PNG(embeddedImageBase64)
console.log('Extracted Message:', extractedMessage)