Program.cs

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("==================");
        Console.WriteLine("图像加密与解密工具");
        Console.WriteLine("==================");
        Console.WriteLine("1: 加密 | 2: 解密");
        string? choice = Console.ReadLine();
        if (string.IsNullOrEmpty(choice))
        {
            Console.WriteLine("无效选择！");
            Console.WriteLine("按任意键退出...");
            Console.ReadKey();
            return;
        }

        if (choice == "1")
        {
            Console.WriteLine("输入宿主图片路径（PNG）：");
            string? hostPath = Console.ReadLine();
            Console.WriteLine("输入第一张隐藏图片路径（PNG）：");
            string? secret1Path = Console.ReadLine();
            Console.WriteLine("输入第二张隐藏图片路径（PNG）：");
            string? secret2Path = Console.ReadLine();

            try
            {
                if (string.IsNullOrEmpty(hostPath)) throw new ArgumentException("宿主图片路径不能为空");
                if (string.IsNullOrEmpty(secret1Path)) throw new ArgumentException("第一张隐藏图片路径不能为空");
                if (string.IsNullOrEmpty(secret2Path)) throw new ArgumentException("第二张隐藏图片路径不能为空");
                if (!File.Exists(hostPath)) throw new FileNotFoundException("宿主图片不存在");
                if (!File.Exists(secret1Path)) throw new FileNotFoundException("第一张隐藏图片不存在");
                if (!File.Exists(secret2Path)) throw new FileNotFoundException("第二张隐藏图片不存在");
                if (!hostPath.ToLower().EndsWith(".png") || !File.ReadAllBytes(hostPath).Take(8).SequenceEqual(new byte[] { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }))
                    throw new ArgumentException("宿主图片必须为有效的 PNG 文件");
                if (!secret1Path.ToLower().EndsWith(".png") || !File.ReadAllBytes(secret1Path).Take(8).SequenceEqual(new byte[] { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }))
                    throw new ArgumentException("第一张隐藏图片必须为有效的 PNG 文件");
                if (!secret2Path.ToLower().EndsWith(".png") || !File.ReadAllBytes(secret2Path).Take(8).SequenceEqual(new byte[] { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }))
                    throw new ArgumentException("第二张隐藏图片必须为有效的 PNG 文件");

                using (Bitmap host = new Bitmap(hostPath))
                using (Bitmap secret1 = new Bitmap(secret1Path))
                using (Bitmap secret2 = new Bitmap(secret2Path))
                {
                    var (encryptedImage, pwd1, pwd2) = ImageCrypto.EncryptImages(host, secret1, secret2);
                    string outputPath = $"encrypted_host_{DateTime.Now.Ticks}.png";
                    encryptedImage.Save(outputPath, ImageFormat.Png);
                    string pwd1Base64 = Convert.ToBase64String(pwd1);
                    string pwd2Base64 = Convert.ToBase64String(pwd2);
                    File.WriteAllText("password1.txt", pwd1Base64);
                    File.WriteAllText("password2.txt", pwd2Base64);
                    Console.WriteLine($"口令1（保存好！）：{pwd1Base64}");
                    Console.WriteLine($"口令2（保存好！）：{pwd2Base64}");
                    Console.WriteLine("口令已保存到 password1.txt 和 password2.txt");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine($"加密失败：{ex.Message}");
            }
        }
        else if (choice == "2")
        {
            Console.WriteLine("输入加密后的宿主图片路径（PNG）：");
            string? encryptedPath = Console.ReadLine();
            Console.WriteLine("输入口令（Base64格式）：");
            string? password = Console.ReadLine();

            try
            {
                if (string.IsNullOrEmpty(encryptedPath)) throw new ArgumentException("加密图片路径不能为空");
                if (string.IsNullOrEmpty(password)) throw new ArgumentException("口令不能为空");
                if (!File.Exists(encryptedPath)) throw new FileNotFoundException("加密图片不存在");
                if (!encryptedPath.ToLower().EndsWith(".png") || !File.ReadAllBytes(encryptedPath).Take(8).SequenceEqual(new byte[] { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }))
                    throw new ArgumentException("加密图片必须为有效的 PNG 文件");

                using (Bitmap encryptedHost = new Bitmap(encryptedPath))
                {
                    byte[] pwd = Convert.FromBase64String(password);
                    if (pwd.Length != 16)
                        throw new ArgumentException("口令长度必须为 16 字节");
                    var (decryptedImage, imageIndex) = ImageCrypto.DecryptImage(encryptedHost, pwd);
                    string outputPath = $"decrypted_{imageIndex}_{DateTime.Now.Ticks}.png";
                    decryptedImage.Save(outputPath, ImageFormat.Png);
                    Console.WriteLine($"，输出文件：{outputPath}");
                    Array.Clear(pwd, 0, pwd.Length);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine($"解密失败：{ex.Message}");
            }
        }
        else
        {
            Console.WriteLine("无效选择！");
        }

        Console.WriteLine("按任意键退出...");
        Console.ReadKey();
    }
}