MDietermann
5dabe89443
Reads hidden messages from encoded PNG images by extracting LSB data from channels indicated by the pixel 0 header.
99 lines
2.7 KiB
C++
99 lines
2.7 KiB
C++
#define _CRT_SECURE_NO_WARNINGS
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#include <iostream>
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#include <string>
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#include <stdexcept>
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#include <cstdlib>
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#define STB_IMAGE_IMPLEMENTATION
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#include "stb_image.h"
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int width, height, channels;
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std::string inputPath, message;
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bool useR, useG, useB;
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unsigned char* data;
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void loadImage() {
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data = stbi_load(inputPath.c_str(), &width, &height, &channels, 0);
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if (!data) {
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throw std::runtime_error("Failed to load image: " + inputPath);
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}
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if (channels < 3) {
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stbi_image_free(data);
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throw std::runtime_error("Image must have at least 3 channels (RGB). Found: " + std::to_string(channels));
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}
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}
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void getInputPath() {
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std::cout << "Enter image file path: ";
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std::getline(std::cin, inputPath);
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if (inputPath.size() >= 2 && inputPath.front() == '"' && inputPath.back() == '"') {
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inputPath = inputPath.substr(1, inputPath.size() - 2);
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}
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}
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void readChannelHeaders() {
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useR = data[0] & 1;
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useG = data[1] & 1;
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useB = data[2] & 1;
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if (!useR && !useG && !useB) {
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stbi_image_free(data);
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throw std::runtime_error("No active channels found in header pixel. Image may not contain a hidden message.");
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}
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std::cout << "Active channels: " << (useR ? "R" : "") << (useG ? "G" : "") << (useB ? "B" : "") << "\n";
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}
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bool processBit(int channelOffset, int base, unsigned char& currentByte, int& bitCount) {
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int bit = data[base + channelOffset] & 1;
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currentByte = (currentByte << 1) | bit;
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bitCount++;
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if (bitCount == 8) {
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if (currentByte == '\0') return true; // null terminator found
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message.push_back(static_cast<char>(currentByte));
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currentByte = 0;
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bitCount = 0;
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}
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return false;
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}
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void readMessage() {
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int totalPixels = width * height;
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unsigned char currentByte = 0;
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int bitCount = 0;
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for (int pixel = 1; pixel < totalPixels; pixel++) {
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int base = pixel * channels;
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if (useR && processBit(0, base, currentByte, bitCount)) return;
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if (useG && processBit(1, base, currentByte, bitCount)) return;
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if (useB && processBit(2, base, currentByte, bitCount)) return;
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}
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}
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int main() {
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try {
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getInputPath();
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loadImage();
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readChannelHeaders();
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readMessage();
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stbi_image_free(data);
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if (message.empty()) {
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std::cout << "No message found (or message is empty).\n";
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} else {
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std::cout << "Hidden message (" << message.size() << " bytes):\n";
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std::cout << message << "\n";
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}
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} catch (const std::exception& e) {
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std::cerr << "Error: " << e.what() << "\n";
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std::cin.get();
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return EXIT_FAILURE;
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}
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std::cin.get();
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return EXIT_SUCCESS;
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}
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