Tool for getting out information hidden in LSB (steganography, nodejs)

lsb.js

'use strict';

var fs = require('fs');


// --------------------------------------------------------
//  Get LSB data from buffer
// --------------------------------------------------------

function bufToLSB(buf, bufBits, bufLE, offset, length, lsbLE) {
    if (length === void(0)) {
        length = buf.length;
    }
    if (lsbLE === void(0)) {
        lsbLE = false;
    }

    var bufWord = bufBits / 8;
    var bufWordOffset = bufLE ? bufWord - 1 : 0;
    var size = (length - offset) / bufWord;
    var lsbBufSize = Math.ceil(size / 8);
    var lsbBuf = (new Buffer(lsbBufSize)).fill(0);
    var lsbBufI = 0;

    var i, tmpBufByte, tmpLSBByte = 0;
    for (i = 0; i < size; i += 1) {
        tmpBufByte = buf[i * bufWord + bufWordOffset + offset];
        if (lsbLE) {
            tmpLSBByte += (tmpBufByte & 1) << (i % 8);
        } else {
            tmpLSBByte = (tmpLSBByte << 1) | (tmpBufByte & 1);
        }
        if (i % 8 === 7) {
            lsbBuf.writeUInt8(tmpLSBByte, lsbBufI++);
            tmpLSBByte = 0;
        }
    }

    return lsbBuf;
}


// --------------------------------------------------------
//  Convenience functions
// --------------------------------------------------------

function buf8ToLSB(buf, offset, length, lsbLE) {
    return bufToLSB(buf, 8, false, offset, length, lsbLE);
}

function buf16LEToLSB(buf, offset, length, lsbLE) {
    return bufToLSB(buf, 16, true, offset, length, lsbLE);
}

function buf16BEToLSB(buf, offset, length, lsbLE) {
    return bufToLSB(buf, 16, false, offset, length, lsbLE);
}


// --------------------------------------------------------
//  Analyze
// --------------------------------------------------------

var buf = fs.readFileSync('audio1.wav');

for (var i = 0; i < 8; i += 1) {
    var lsb = buf16LEToLSB(buf, 44 + i);
    process.stdout.write(lsb.toString() + '\n');
}

for (var i = 0; i < 8; i += 1) {
    var lsb = buf16BEToLSB(buf, 44 + i);
    process.stdout.write(lsb.toString() + '\n');
}